Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.
A generic term for fats and lipoids, the alcohol-ether-soluble constituents of protoplasm, which are insoluble in water. They comprise the fats, fatty oils, essential oils, waxes, phospholipids, glycolipids, sulfolipids, aminolipids, chromolipids (lipochromes), and fatty acids. (Grant & Hackh's Chemical Dictionary, 5th ed)
A synthetic phospholipid used in liposomes and lipid bilayers for the study of biological membranes.
The motion of phospholipid molecules within the lipid bilayer, dependent on the classes of phospholipids present, their fatty acid composition and degree of unsaturation of the acyl chains, the cholesterol concentration, and temperature.
Synthetic phospholipid used in liposomes and lipid bilayers to study biological membranes. It is also a major constituent of PULMONARY SURFACTANTS.
Physiological processes in biosynthesis (anabolism) and degradation (catabolism) of LIPIDS.
The characteristic three-dimensional shape of a molecule.
Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.
Artificially produced membranes, such as semipermeable membranes used in artificial kidney dialysis (RENAL DIALYSIS), monomolecular and bimolecular membranes used as models to simulate biological CELL MEMBRANES. These membranes are also used in the process of GUIDED TISSUE REGENERATION.
Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a choline moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and choline and 2 moles of fatty acids.
Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.
A change of a substance from one form or state to another.
Lipid A is the biologically active component of lipopolysaccharides. It shows strong endotoxic activity and exhibits immunogenic properties.
The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.
A nitrogen-free class of lipids present in animal and particularly plant tissues and composed of one mole of glycerol and 1 or 2 moles of phosphatidic acid. Members of this group differ from one another in the nature of the fatty acids released on hydrolysis.
A cyclic nonadecapeptide antibiotic that can act as an ionophore and is produced by strains of Trichoderma viride. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
The physical characteristics and processes of biological systems.
Single membrane vesicles, generally made of PHOSPHOLIPIDS.
A group of peptide antibiotics from BACILLUS brevis. Gramicidin C or S is a cyclic, ten-amino acid polypeptide and gramicidins A, B, D are linear. Gramicidin is one of the two principal components of TYROTHRICIN.
Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to an ethanolamine moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and ethanolamine and 2 moles of fatty acids.
Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.
Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.
A type of scanning probe microscopy in which a probe systematically rides across the surface of a sample being scanned in a raster pattern. The vertical position is recorded as a spring attached to the probe rises and falls in response to peaks and valleys on the surface. These deflections produce a topographic map of the sample.
Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).
Differential thermal analysis in which the sample compartment of the apparatus is a differential calorimeter, allowing an exact measure of the heat of transition independent of the specific heat, thermal conductivity, and other variables of the sample.
A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.
The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.
The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.
The ability of a substrate to allow the passage of ELECTRONS.
A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)
Lipids, predominantly phospholipids, cholesterol and small amounts of glycolipids found in membranes including cellular and intracellular membranes. These lipids may be arranged in bilayers in the membranes with integral proteins between the layers and peripheral proteins attached to the outside. Membrane lipids are required for active transport, several enzymatic activities and membrane formation.
The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.
Particles consisting of aggregates of molecules held loosely together by secondary bonds. The surface of micelles are usually comprised of amphiphatic compounds that are oriented in a way that minimizes the energy of interaction between the micelle and its environment. Liquids that contain large numbers of suspended micelles are referred to as EMULSIONS.
Detergent-insoluble CELL MEMBRANE components. They are enriched in SPHINGOLIPIDS and CHOLESTEROL and clustered with glycosyl-phosphatidylinositol (GPI)-anchored proteins.
Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.
Peroxidase catalyzed oxidation of lipids using hydrogen peroxide as an electron acceptor.
The thermodynamic interaction between a substance and WATER.
The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.
A class of sphingolipids found largely in the brain and other nervous tissue. They contain phosphocholine or phosphoethanolamine as their polar head group so therefore are the only sphingolipids classified as PHOSPHOLIPIDS.
Measurement of the intensity and quality of fluorescence.
Characteristics or attributes of the outer boundaries of objects, including molecules.
Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a serine moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and serine and 2 moles of fatty acids.
The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.
An anionic compound that is used as a reagent for determination of potassium, ammonium, rubidium, and cesium ions. It also uncouples oxidative phosphorylation and forms complexes with biological materials, and is used in biological assays.
A computer simulation developed to study the motion of molecules over a period of time.
Condition of having pores or open spaces. This often refers to bones, bone implants, or bone cements, but can refer to the porous state of any solid substance.
Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.
Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.
The accumulation of an electric charge on a object
The rate dynamics in chemical or physical systems.
The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
Small cationic peptides that are an important component, in most species, of early innate and induced defenses against invading microbes. In animals they are found on mucosal surfaces, within phagocytic granules, and on the surface of the body. They are also found in insects and plants. Among others, this group includes the DEFENSINS, protegrins, tachyplesins, and thionins. They displace DIVALENT CATIONS from phosphate groups of MEMBRANE LIPIDS leading to disruption of the membrane.
Batrachotoxin is the 20-alpha-bromobenzoate of batrachotoxin A; they are toxins from the venom of a small Colombian frog, Phyllobates aurotaenia, cause release of acetylcholine, destruction of synaptic vesicles and depolarization of nerve and muscle fibers.
The adhesion of gases, liquids, or dissolved solids onto a surface. It includes adsorptive phenomena of bacteria and viruses onto surfaces as well. ABSORPTION into the substance may follow but not necessarily.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Basic polypeptide from the venom of the honey bee (Apis mellifera). It contains 26 amino acids, has cytolytic properties, causes contracture of muscle, releases histamine, and disrupts surface tension, probably due to lysis of cell and mitochondrial membranes.
Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.
The force acting on the surface of a liquid, tending to minimize the area of the surface. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.
NMR spectroscopy on small- to medium-size biological macromolecules. This is often used for structural investigation of proteins and nucleic acids, and often involves more than one isotope.
Computer-based representation of physical systems and phenomena such as chemical processes.
The adherence and merging of cell membranes, intracellular membranes, or artificial membranes to each other or to viruses, parasites, or interstitial particles through a variety of chemical and physical processes.
The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).
A fluorescent compound that emits light only in specific configurations in certain lipid media. It is used as a tool in the study of membrane lipids.
The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).
The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.
The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.
Peroxides produced in the presence of a free radical by the oxidation of unsaturated fatty acids in the cell in the presence of molecular oxygen. The formation of lipid peroxides results in the destruction of the original lipid leading to the loss of integrity of the membranes. They therefore cause a variety of toxic effects in vivo and their formation is considered a pathological process in biological systems. Their formation can be inhibited by antioxidants, such as vitamin E, structural separation or low oxygen tension.
A spectroscopic technique in which a range of wavelengths is presented simultaneously with an interferometer and the spectrum is mathematically derived from the pattern thus obtained.
The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.
Deuterium. The stable isotope of hydrogen. It has one neutron and one proton in the nucleus.
Purifying or cleansing agents, usually salts of long-chain aliphatic bases or acids, that exert cleansing (oil-dissolving) and antimicrobial effects through a surface action that depends on possessing both hydrophilic and hydrophobic properties.
Colloids with a solid continuous phase and liquid as the dispersed phase; gels may be unstable when, due to temperature or other cause, the solid phase liquefies; the resulting colloid is called a sol.
Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.
The diversion of RADIATION (thermal, electromagnetic, or nuclear) from its original path as a result of interactions or collisions with atoms, molecules, or larger particles in the atmosphere or other media. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
Measurement of the polarization of fluorescent light from solutions or microscopic specimens. It is used to provide information concerning molecular size, shape, and conformation, molecular anisotropy, electronic energy transfer, molecular interaction, including dye and coenzyme binding, and the antigen-antibody reaction.
Molecules which contain an atom or a group of atoms exhibiting an unpaired electron spin that can be detected by electron spin resonance spectroscopy and can be bonded to another molecule. (McGraw-Hill Dictionary of Chemical and Technical Terms, 4th ed)
A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.
A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
A class of antimicrobial peptides discovered in the skin of XENOPUS LAEVIS. They kill bacteria by permeabilizing cell membranes without exhibiting significant toxicity against mammalian cells.
The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.
The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
A tetrameric calcium release channel in the SARCOPLASMIC RETICULUM membrane of SMOOTH MUSCLE CELLS, acting oppositely to SARCOPLASMIC RETICULUM CALCIUM-TRANSPORTING ATPASES. It is important in skeletal and cardiac excitation-contraction coupling and studied by using RYANODINE. Abnormalities are implicated in CARDIAC ARRHYTHMIAS and MUSCULAR DISEASES.
Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.
An atom or group of atoms that have a positive or negative electric charge due to a gain (negative charge) or loss (positive charge) of one or more electrons. Atoms with a positive charge are known as CATIONS; those with a negative charge are ANIONS.
Porins are protein molecules that were originally found in the outer membrane of GRAM-NEGATIVE BACTERIA and that form multi-meric channels for the passive DIFFUSION of WATER; IONS; or other small molecules. Porins are present in bacterial CELL WALLS, as well as in plant, fungal, mammalian and other vertebrate CELL MEMBRANES and MITOCHONDRIAL MEMBRANES.
Salts and esters of the 12-carbon saturated monocarboxylic acid--lauric acid.
Materials which have structured components with at least one dimension in the range of 1 to 100 nanometers. These include NANOCOMPOSITES; NANOPARTICLES; NANOTUBES; and NANOWIRES.
The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.
A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.
A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.
A naphthalene derivative with carcinogenic action.
Transparent, tasteless crystals found in nature as agate, amethyst, chalcedony, cristobalite, flint, sand, QUARTZ, and tridymite. The compound is insoluble in water or acids except hydrofluoric acid.
A group of GLYCOLIPIDS in which the sugar group is GALACTOSE. They are distinguished from GLYCOSPHINGOLIPIDS in lacking nitrogen. They constitute the majority of MEMBRANE LIPIDS in PLANTS.
Venoms produced by FISHES, including SHARKS and sting rays, usually delivered by spines. They contain various substances, including very labile toxins that affect the HEART specifically and all MUSCLES generally.
Nonionic surfactant mixtures varying in the number of repeating ethoxy (oxy-1,2-ethanediyl) groups. They are used as detergents, emulsifiers, wetting agents, defoaming agents, etc. Octoxynol-9, the compound with 9 repeating ethoxy groups, is a spermatocide.
The homogeneous mixtures formed by the mixing of a solid, liquid, or gaseous substance (solute) with a liquid (the solvent), from which the dissolved substances can be recovered by physical processes. (From Grant & Hackh's Chemical Dictionary, 5th ed)
Organic, monobasic acids derived from hydrocarbons by the equivalent of oxidation of a methyl group to an alcohol, aldehyde, and then acid. Fatty acids are saturated and unsaturated (FATTY ACIDS, UNSATURATED). (Grant & Hackh's Chemical Dictionary, 5th ed)
A benzofuran derivative used as a protein reagent since the terminal N-NBD-protein conjugate possesses interesting fluorescence and spectral properties. It has also been used as a covalent inhibitor of both beef heart mitochondrial ATPase and bacterial ATPase.
Liquids that dissolve other substances (solutes), generally solids, without any change in chemical composition, as, water containing sugar. (Grant & Hackh's Chemical Dictionary, 5th ed)
Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.
Agents that modify interfacial tension of water; usually substances that have one lipophilic and one hydrophilic group in the molecule; includes soaps, detergents, emulsifiers, dispersing and wetting agents, and several groups of antiseptics.
The scattering of NEUTRONS by matter, especially crystals, with accompanying variation in intensity due to interference effects. It is useful in CRYSTALLOGRAPHY and POWDER DIFFRACTION.
The ability of a substance to be dissolved, i.e. to form a solution with another substance. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
A low-energy attractive force between hydrogen and another element. It plays a major role in determining the properties of water, proteins, and other compounds.
The study of CHEMICAL PHENOMENA and processes in terms of the underlying PHYSICAL PHENOMENA and processes.
Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.
Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kDa in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.
A trace element that constitutes about 27.6% of the earth's crust in the form of SILICON DIOXIDE. It does not occur free in nature. Silicon has the atomic symbol Si, atomic number 14, and atomic weight [28.084; 28.086].
Electrically neutral elementary particles found in all atomic nuclei except light hydrogen; the mass is equal to that of the proton and electron combined and they are unstable when isolated from the nucleus, undergoing beta decay. Slow, thermal, epithermal, and fast neutrons refer to the energy levels with which the neutrons are ejected from heavier nuclei during their decay.
Derivatives of ammonium compounds, NH4+ Y-, in which all four of the hydrogens bonded to nitrogen have been replaced with hydrocarbyl groups. These are distinguished from IMINES which are RN=CR2.
The development and use of techniques to study physical phenomena and construct structures in the nanoscale size range or smaller.
Any of the numerous types of clay which contain varying proportions of Al2O3 and SiO2. They are made synthetically by heating aluminum fluoride at 1000-2000 degrees C with silica and water vapor. (From Hawley's Condensed Chemical Dictionary, 11th ed)
A physical property showing different values in relation to the direction in or along which the measurement is made. The physical property may be with regard to thermal or electric conductivity or light refraction. In crystallography, it describes crystals whose index of refraction varies with the direction of the incident light. It is also called acolotropy and colotropy. The opposite of anisotropy is isotropy wherein the same values characterize the object when measured along axes in all directions.
Physical motion, i.e., a change in position of a body or subject as a result of an external force. It is distinguished from MOVEMENT, a process resulting from biological activity.
Cytoplasm stored in an egg that contains nutritional reserves for the developing embryo. It is rich in polysaccharides, lipids, and proteins.
Calcium and magnesium salts used therapeutically in hepatobiliary dysfunction.
Resistance and recovery from distortion of shape.
The measurement of the quantity of heat involved in various processes, such as chemical reactions, changes of state, and formations of solutions, or in the determination of the heat capacities of substances. The fundamental unit of measurement is the joule or the calorie (4.184 joules). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
Thin layers of tissue which cover parts of the body, separate adjacent cavities, or connect adjacent structures.
A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.
The assembly of the QUATERNARY PROTEIN STRUCTURE of multimeric proteins (MULTIPROTEIN COMPLEXES) from their composite PROTEIN SUBUNITS.
Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).
The ability of a substrate to retain an electrical charge.
Spectrophotometry in the infrared region, usually for the purpose of chemical analysis through measurement of absorption spectra associated with rotational and vibrational energy levels of molecules. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
Elements of limited time intervals, contributing to particular results or situations.
The physical phenomena describing the structure and properties of atoms and molecules, and their reaction and interaction processes.
A network of tubules and sacs in the cytoplasm of SKELETAL MUSCLE FIBERS that assist with muscle contraction and relaxation by releasing and storing calcium ions.
Voltage-dependent cell membrane glycoproteins selectively permeable to calcium ions. They are categorized as L-, T-, N-, P-, Q-, and R-types based on the activation and inactivation kinetics, ion specificity, and sensitivity to drugs and toxins. The L- and T-types are present throughout the cardiovascular and central nervous systems and the N-, P-, Q-, & R-types are located in neuronal tissue.
Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.
Proteins obtained from species in the class of AMPHIBIANS.
An antiviral that is used in the prophylactic or symptomatic treatment of influenza A. It is also used as an antiparkinsonian agent, to treat extrapyramidal reactions, and for postherpetic neuralgia. The mechanisms of its effects in movement disorders are not well understood but probably reflect an increase in synthesis and release of dopamine, with perhaps some inhibition of dopamine uptake.
Any compound containing one or more monosaccharide residues bound by a glycosidic linkage to a hydrophobic moiety such as an acylglycerol (see GLYCERIDES), a sphingoid, a ceramide (CERAMIDES) (N-acylsphingoid) or a prenyl phosphate. (From IUPAC's webpage)
A steroid of interest both because its biosynthesis in FUNGI is a target of ANTIFUNGAL AGENTS, notably AZOLES, and because when it is present in SKIN of animals, ULTRAVIOLET RAYS break a bond to result in ERGOCALCIFEROL.
A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
A family of spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one derivatives. These are used as dyes, as indicators for various metals, and as fluorescent labels in immunoassays.
The temperature at which a substance changes from one state or conformation of matter to another.
Substances produced from the reaction between acids and bases; compounds consisting of a metal (positive) and nonmetal (negative) radical. (Grant & Hackh's Chemical Dictionary, 5th ed)
Polymers of ETHYLENE OXIDE and water, and their ethers. They vary in consistency from liquid to solid depending on the molecular weight indicated by a number following the name. They are used as SURFACTANTS, dispersing agents, solvents, ointment and suppository bases, vehicles, and tablet excipients. Some specific groups are NONOXYNOLS, OCTOXYNOLS, and POLOXAMERS.
Proteins from BACTERIA and FUNGI that are soluble enough to be secreted to target ERYTHROCYTES and insert into the membrane to form beta-barrel pores. Biosynthesis may be regulated by HEMOLYSIN FACTORS.
The parts of a macromolecule that directly participate in its specific combination with another molecule.
Theoretical representations that simulate the behavior or activity of systems, processes, or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.
A specific monosialoganglioside that accumulates abnormally within the nervous system due to a deficiency of GM1-b-galactosidase, resulting in GM1 gangliosidosis.
Salts and esters of the 14-carbon saturated monocarboxylic acid--myristic acid.
The performance of dissections, injections, surgery, etc., by the use of micromanipulators (attachments to a microscope) that manipulate tiny instruments.
Acidic phospholipids composed of two molecules of phosphatidic acid covalently linked to a molecule of glycerol. They occur primarily in mitochondrial inner membranes and in bacterial plasma membranes. They are the main antigenic components of the Wassermann-type antigen that is used in nontreponemal SYPHILIS SERODIAGNOSIS.
Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.
Proteins prepared by recombinant DNA technology.
FATTY ACIDS in which the carbon chain contains one or more double or triple carbon-carbon bonds.
The destruction of ERYTHROCYTES by many different causal agents such as antibodies, bacteria, chemicals, temperature, and changes in tonicity.
Quartz (SiO2). A glassy or crystalline form of silicon dioxide. Many colored varieties are semiprecious stones. (From Grant & Hackh's Chemical Dictionary, 5th ed)
A type of FLUORESCENCE SPECTROSCOPY using two FLUORESCENT DYES with overlapping emission and absorption spectra, which is used to indicate proximity of labeled molecules. This technique is useful for studying interactions of molecules and PROTEIN FOLDING.
The generic name for the group of aliphatic hydrocarbons Cn-H2n+2. They are denoted by the suffix -ane. (Grant & Hackh's Chemical Dictionary, 5th ed)
Members of the class of neutral glycosphingolipids. They are the basic units of SPHINGOLIPIDS. They are sphingoids attached via their amino groups to a long chain fatty acyl group. They abnormally accumulate in FABRY DISEASE.
Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.
In statistics, a technique for numerically approximating the solution of a mathematical problem by studying the distribution of some random variable, often generated by a computer. The name alludes to the randomness characteristic of the games of chance played at the gambling casinos in Monte Carlo. (From Random House Unabridged Dictionary, 2d ed, 1993)
An essential amino acid that is necessary for normal growth in infants and for NITROGEN balance in adults. It is a precursor of INDOLE ALKALOIDS in plants. It is a precursor of SEROTONIN (hence its use as an antidepressant and sleep aid). It can be a precursor to NIACIN, albeit inefficiently, in mammals.
Phospholipids which have an alcohol moiety in ethereal linkage with a saturated or unsaturated aliphatic alcohol. They are usually derivatives of phosphoglycerols or phosphatidates. The other two alcohol groups of the glycerol backbone are usually in ester linkage. These compounds are widely distributed in animal tissues.
Derivatives of phosphatidic acid in which the hydrophobic regions are composed of two fatty acids and a polar alcohol is joined to the C-3 position of glycerol through a phosphodiester bond. They are named according to their polar head groups, such as phosphatidylcholine and phosphatidylethanolamine.
Stable phosphorus atoms that have the same atomic number as the element phosphorus, but differ in atomic weight. P-31 is a stable phosphorus isotope.
The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.
Proteins isolated from the outer membrane of Gram-negative bacteria.
The semi-permeable outer structure of a red blood cell. It is known as a red cell 'ghost' after HEMOLYSIS.
The formation of crystalline substances from solutions or melts. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
The property of emitting radiation while being irradiated. The radiation emitted is usually of longer wavelength than that incident or absorbed, e.g., a substance can be irradiated with invisible radiation and emit visible light. X-ray fluorescence is used in diagnosis.
The transfer of energy of a given form among different scales of motion. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed). It includes the transfer of kinetic energy and the transfer of chemical energy. The transfer of chemical energy from one molecule to another depends on proximity of molecules so it is often used as in techniques to measure distance such as the use of FORSTER RESONANCE ENERGY TRANSFER.
Protein-lipid combinations abundant in brain tissue, but also present in a wide variety of animal and plant tissues. In contrast to lipoproteins, they are insoluble in water, but soluble in a chloroform-methanol mixture. The protein moiety has a high content of hydrophobic amino acids. The associated lipids consist of a mixture of GLYCEROPHOSPHATES; CEREBROSIDES; and SULFOGLYCOSPHINGOLIPIDS; while lipoproteins contain PHOSPHOLIPIDS; CHOLESTEROL; and TRIGLYCERIDES.
Fatty acids which are unsaturated in only one position.
Substances and drugs that lower the SURFACE TENSION of the mucoid layer lining the PULMONARY ALVEOLI.
The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.
Thin structures that encapsulate subcellular structures or ORGANELLES in EUKARYOTIC CELLS. They include a variety of membranes associated with the CELL NUCLEUS; the MITOCHONDRIA; the GOLGI APPARATUS; the ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.
Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function.
A method used to study the lateral movement of MEMBRANE PROTEINS and LIPIDS. A small area of a cell membrane is bleached by laser light and the amount of time necessary for unbleached fluorescent marker-tagged proteins to diffuse back into the bleached site is a measurement of the cell membrane's fluidity. The diffusion coefficient of a protein or lipid in the membrane can be calculated from the data. (From Segen, Current Med Talk, 1995).
Negatively charged atoms, radicals or groups of atoms which travel to the anode or positive pole during electrolysis.
Preparation for electron microscopy of minute replicas of exposed surfaces of the cell which have been ruptured in the frozen state. The specimen is frozen, then cleaved under high vacuum at the same temperature. The exposed surface is shadowed with carbon and platinum and coated with carbon to obtain a carbon replica.

Three-dimensional structure of a recombinant gap junction membrane channel. (1/7162)

Gap junction membrane channels mediate electrical and metabolic coupling between adjacent cells. The structure of a recombinant cardiac gap junction channel was determined by electron crystallography at resolutions of 7.5 angstroms in the membrane plane and 21 angstroms in the vertical direction. The dodecameric channel was formed by the end-to-end docking of two hexamers, each of which displayed 24 rods of density in the membrane interior, which is consistent with an alpha-helical conformation for the four transmembrane domains of each connexin subunit. The transmembrane alpha-helical rods contrasted with the double-layered appearance of the extracellular domains. Although not indicative for a particular type of secondary structure, the protein density that formed the extracellular vestibule provided a tight seal to exclude the exchange of substances with the extracellular milieu.  (+info)

Gating connexin 43 channels reconstituted in lipid vesicles by mitogen-activated protein kinase phosphorylation. (2/7162)

The regulation of gap junctional permeability by phosphorylation was examined in a model system in which connexin 43 (Cx43) gap junction hemichannels were reconstituted in lipid vesicles. Cx43 was immunoaffinity-purified from rat brain, and Cx43 channels were reconstituted into unilamellar phospholipid liposomes. The activities of the reconstituted channels were measured by monitoring liposome permeability. Liposomes containing the Cx43 protein were fractionated on the basis of permeability to sucrose using sedimentation in an iso-osmolar density gradient. The gradient allowed separation of the sucrose-permeable and -impermeable liposomes. Liposomes that were permeable to sucrose were also permeable to the communicating dye molecule lucifer yellow. Permeability, and therefore activity of the reconstituted Cx43 channels, were directly dependent on the state of Cx43 phosphorylation. The permeability of liposomes containing Cx43 channels was increased by treatment of liposomes with calf intestinal phosphatase. Moreover, liposomes formed with Cx43 that had been dephosphorylated by calf intestinal phosphatase treatment showed increased permeability to sucrose. The role of phosphorylation in the gating mechanism of Cx43 channels was supported further by the observation that phosphorylation of Cx43 by mitogen-activated protein kinase reversibly reduced the permeability of liposomes containing dephosphorylated Cx43. Our results show a direct correlation between gap junctional permeability and the phosphorylation state of Cx43.  (+info)

Calculation of a Gap restoration in the membrane skeleton of the red blood cell: possible role for myosin II in local repair. (3/7162)

Human red blood cells contain all of the elements involved in the formation of nonmuscle actomyosin II complexes (V. M. Fowler. 1986. J. Cell. Biochem. 31:1-9; 1996. Curr. Opin. Cell Biol. 8:86-96). No clear function has yet been attributed to these complexes. Using a mathematical model for the structure of the red blood cell spectrin skeleton (M. J. Saxton. 1992. J. Theor. Biol. 155:517-536), we have explored a possible role for myosin II bipolar minifilaments in the restoration of the membrane skeleton, which may be locally damaged by major mechanical or chemical stress. We propose that the establishment of stable links between distant antiparallel actin protofilaments after a local myosin II activation may initiate the repair of the disrupted area. We show that it is possible to define conditions in which the calculated number of myosin II minifilaments bound to actin protofilaments is consistent with the estimated number of myosin II minifilaments present in the red blood cells. A clear restoration effect can be observed when more than 50% of the spectrin polymers of a defined area are disrupted. It corresponds to a significant increase in the spectrin density in the protein free region of the membrane. This may be involved in a more complex repair process of the red blood cell membrane, which includes the vesiculation of the bilayer and the compaction of the disassembled spectrin network.  (+info)

Solid-state NMR and hydrogen-deuterium exchange in a bilayer-solubilized peptide: structural and mechanistic implications. (4/7162)

Hydrogen-deuterium exchange has been monitored by solid-state NMR to investigate the structure of gramicidin M in a lipid bilayer and to investigate the mechanisms for polypeptide insertion into a lipid bilayer. Through exchange it is possible to observe 15N-2H dipolar interactions in oriented samples that yield precise structural constraints. In separate experiments the pulse sequence SFAM was used to measure dipolar distances in this structure, showing that the dimer is antiparallel. The combined use of orientational and distance constraints is shown to be a powerful structural approach. By monitoring the hydrogen-deuterium exchange at different stages in the insertion of peptides into a bilayer environment it is shown that dimeric gramicidin is inserted into the bilayer intact, i.e., without separating into monomer units. The exchange mechanism is investigated for various sites and support for a relayed imidic acid mechanism is presented. Both acid and base catalyzed mechanisms may be operable. The nonexchangeable sites clearly define a central core to which water is inaccessible or hydroxide or hydronium ion is not even momentarily stable. This provides strong evidence that this is a nonconducting state.  (+info)

Molecular dynamics study of substance P peptides in a biphasic membrane mimic. (5/7162)

Two neuropeptides, substance P (SP) and SP-tyrosine-8 (SP-Y8), have been studied by molecular dynamics (MD) simulation in a TIP3P water/CCl4 biphasic solvent system as a mimic for the water-membrane system. Initially, distance restraints derived from NMR nuclear Overhauser enhancements (NOE) were incorporated in the restrained MD (RMD) in the equilibration stage of the simulation. The starting orientation/position of the peptides for the MD simulation was either parallel to the water/CCl4 interface or in a perpendicular/insertion mode. In both cases the peptides equilibrated and adopted a near-parallel orientation within approximately 250 ps. After equilibration, the conformation and orientation of the peptides, the solvation of both the backbone and the side chain of the residues, hydrogen bonding, and the dynamics of the peptides were analyzed from trajectories obtained in the RMD or the subsequent free MD (where the NOE restraints were removed). These analyses showed that the peptide backbone of nearly all residues are either solvated by water or are hydrogen-bonded. This is seen to be an important factor against the insertion mode of interaction. Most of the interactions with the hydrophobic phase come from the hydrophobic interactions of the side chains of Pro-4, Phe-7, Phe-8, Leu-10, and Met-11 for SP, and Phe-7, Leu-10, Met-11 and, to a lesser extent, Tyr-8 in SP-Y8. Concerted conformational transitions took place in the time frame of hundreds of picoseconds. The concertedness of the transition was due to the tendency of the peptide to maintain the necessary secondary structure to position the peptide properly with respect to the water/CCl4 interface.  (+info)

Molecular dynamics study of substance P peptides partitioned in a sodium dodecylsulfate micelle. (6/7162)

Two neuropeptides, substance P (SP) and SP-tyrosine-8 (SP-Y8), have been studied by molecular dynamics (MD) simulation in an explicit sodium dodecylsulfate (SDS) micelle. Initially, distance restraints derived from NMR nuclear Overhauser enhancements (NOE) were incorporated in the restrained MD (RMD) during the equilibration stage of the simulation. It was shown that when SP-Y8 was initially placed in an insertion (perpendicular) configuration, the peptide equilibrated to a surface-bound (parallel) configuration in approximately 450 ps. After equilibration, the conformation and orientation of the peptides, the solvation of both the backbone and the side chain of the residues, hydrogen bonding, and the dynamics of the peptides were analyzed from trajectories obtained from the RMD or the subsequent free MD (where the NOE restraints were removed). These analyses showed that the peptide backbones of all residues are either solvated by water or are hydrogen-bonded. This is seen to be an important factor against the insertion mode of interaction. Most of the interactions come from the hydrophobic interaction between the side chains of Lys-3, Pro-4, Phe-7, Phe-8, Leu-10, and Met-11 for SP, from Lys-3, Phe-7, Leu-10, and Met-11 in SP-Y8, and the micellar interior. Significant interactions, electrostatic and hydrogen bonding, between the N-terminal residues, Arg-Pro-Lys, and the micellar headgroups were observed. These latter interactions served to affect both the structure and, especially, the flexibility, of the N-terminus. The results from simulation of the same peptides in a water/CCl4 biphasic cell were compared with the results of the present study, and the validity of using the biphasic system as an approximation for peptide-micelle or peptide-bilayer systems is discussed.  (+info)

Charge pairing of headgroups in phosphatidylcholine membranes: A molecular dynamics simulation study. (7/7162)

Molecular dynamics simulation of the hydrated dimyristoylphosphatidylcholine (DMPC) bilayer membrane in the liquid-crystalline phase was carried out for 5 ns to study the interaction among DMPC headgroups in the membrane/water interface region. The phosphatidylcholine headgroup contains a positively charged choline group and negatively charged phosphate and carbonyl groups, although it is a neutral molecule as a whole. Our previous study (Pasenkiewicz-Gierula, M., Y. Takaoka, H. Miyagawa, K. Kitamura, and A. Kusumi. 1997. J. Phys. Chem. 101:3677-3691) showed the formation of water cross-bridges between negatively charged groups in which a water molecule is simultaneously hydrogen bonded to two DMPC molecules. Water bridges link 76% of DMPC molecules in the membrane. In the present study we show that relatively stable charge associations (charge pairs) are formed between the positively and negatively charged groups of two DMPC molecules. Charge pairs link 93% of DMPC molecules in the membrane. Water bridges and charge pairs together form an extended network of interactions among DMPC headgroups linking 98% of all membrane phospholipids. The average lifetimes of DMPC-DMPC associations via charge pairs, water bridges and both, are at least 730, 1400, and over 1500 ps, respectively. However, these associations are dynamic states and they break and re-form several times during their lifetime.  (+info)

Kinetic and thermodynamic aspects of lipid translocation in biological membranes. (8/7162)

A theoretical analysis of the lipid translocation in cellular bilayer membranes is presented. We focus on an integrative model of active and passive transport processes determining the asymmetrical distribution of the major lipid components between the monolayers. The active translocation of the aminophospholipids phosphatidylserine and phosphatidylethanolamine is mathematically described by kinetic equations resulting from a realistic ATP-dependent transport mechanism. Concerning the passive transport of the aminophospholipids as well as of phosphatidylcholine, sphingomyelin, and cholesterol, two different approaches are used. The first treatment makes use of thermodynamic flux-force relationships. Relevant forces are transversal concentration differences of the lipids as well as differences in the mechanical states of the monolayers due to lateral compressions. Both forces, originating primarily from the operation of an aminophospholipid translocase, are expressed as functions of the lipid compositions of the two monolayers. In the case of mechanical forces, lipid-specific parameters such as different molecular surface areas and compression force constants are taken into account. Using invariance principles, it is shown how the phenomenological coefficients depend on the total lipid amounts. In a second approach, passive transport is analyzed in terms of kinetic mechanisms of carrier-mediated translocation, where mechanical effects are incorporated into the translocation rate constants. The thermodynamic as well as the kinetic approach are applied to simulate the time-dependent redistribution of the lipid components in human red blood cells. In the thermodynamic model the steady-state asymmetrical lipid distribution of erythrocyte membranes is simulated well under certain parameter restrictions: 1) the time scales of uncoupled passive transbilayer movement must be different among the lipid species; 2) positive cross-couplings of the passive lipid fluxes are needed, which, however, may be chosen lipid-unspecifically. A comparison of the thermodynamic and the kinetic approaches reveals that antiport mechanisms for passive lipid movements may be excluded. Simulations with kinetic symport mechanisms are in qualitative agreement with experimental data but show discrepancies in the asymmetrical distribution for sphingomyelin.  (+info)

TY - JOUR. T1 - Fluorescence modulation sensing of positively and negatively charged proteins on lipid bilayers. AU - Robison, Aaron D.. AU - Huang, Da. AU - Jung, Hyunsook. AU - Cremer, Paul S.. PY - 2013/1/1. Y1 - 2013/1/1. N2 - Background: Detecting ligand-receptor binding on cell membrane surfaces is required to understand their function and behavior. Detection platforms can also provide an avenue for the development of medical devices and sensor biotechnology. The use of fluorescence techniques for such purposes is highly desirable as they provide high sensitivity. Herein, we describe a technique that utilizes the sensitivity of fluorescence without directly tagging the analyte of interest to monitor ligand-receptor interactions on supported lipid bilayers. The fluorescence signal is modulated according to the charge state of the target analyte. The binding event elicits protonation or deprotonation of pH-responsive reporter dyes embedded in the lipid bilayer. Methods: Supported lipid ...
Lipid flip-flop and its associated transient pore formation are key thermodynamic properties of living cell membranes. However, there is a lack of understanding of whether ionic imbalance that exists ubiquitously across cell membranes affects lipid flip-flop and its associated functions. Potential of mean force calculations show that the free-energy barrier of lipid flip-flop on the extracellular leaflet reduces with the presence of ionic imbalance, whereas the barrier on the intracellular leaflet is generally not affected. The linear decrease of the activation energy of lipid flip-flop on the extracellular leaflet is consistent with the experimentally measured conductance-voltage relationship of zwitterionic lipid bilayers. This suggests: 1) lipid flip-flop has a directionality under physiological conditions and phospholipids accumulate at a rate on the order of 105 mu m(-2) h(-1) on the cytoplasmic side of cell membranes; 2) ion permeation across a lipid membrane is moderated by lipid ...
Understanding interactions between functionalized gold nanoparticles (NPs) and lipid bilayers is essential for their use in biomedical applications. Experiments and continuum-scale simulations have suggested that small (~5 nm diameter) cationic NPs aggregate when adsorbed to the surface of zwitterionic lipid bilayers despite being stable in aqueous solution, suggesting that bilayer-mediated interactions facilitate assembly. Determining the origin of these effects and the impact of other bilayer features, such as lipid phase separation, on the interfacial assembly of NPs would enable the design of NPs for applications that require NP assembly, such as photothermal therapy.. In this work, we use chemically specific coarse-grained molecular dynamics simulations to show that cationic NP adsorption to lipid bilayers is driven by a balance between favorable NP-lipid interactions and the unfavorable mechanical deformation of the bilayer to create local curvature. The minimization of induced curvature ...
Defensins are cationic, cysteine-rich peptides (Mr = 3500-4000) found in the cytoplasmic granules of neutrophils and macrophages. These peptides possess broad antimicrobial activity in vitro against bacteria, fungi, tumor cells, and enveloped viruses, and they are believed to contribute to the oxygen-independent antimicrobial defenses of neutrophils and macrophages. Pathophysiologic studies in vitro have pointed to the plasma membrane as a possible target for the cytotoxic action of defensins. We report here that defensins form voltage-dependent, weakly anion-selective channels in planar lipid bilayer membranes, and we suggest that this channel-forming ability contributes to their antimicrobial properties observed in vitro.. ...
Large granular lymphocytes, mediators of NK activity, bind to other cells using both the LFA (lymphocyte function-associated)-1-ICAM and the CD2-LFA-3 adhesion pathways. Here we have studied the motility and ultrastructure of large granule lymphocyte (LGL) on lipid bilayers containing purified LFA-1, ICAM-1, and the transmembrane and glycophosphatidylinositol isoforms of LFA-3. LGLs moved at 8 microns/min on ICAM-1 but poorly (less than 1 microns/min) on its receptor pair LFA-1. TM-LFA-3 promoted locomotion at a rate close to ICAM-1, whereas the cells were less motile on GPI-LFA-3. The difference in the rates of locomotion on the two isoforms of LFA-3 is presumably attributable to their difference in anchoring and lateral mobility in the bilayer. In spite of the variation in motility the ultrastructure of the adhering cells was similar on all four ligands. LGLs contacted the membrane variably, i.e., cells adhering only in a few small areas or in larger areas were detected on each ligand. The relative
Large granular lymphocytes, mediators of NK activity, bind to other cells using both the LFA (lymphocyte function-associated)-1-ICAM and the CD2-LFA-3 adhesion pathways. Here we have studied the motility and ultrastructure of large granule lymphocyte (LGL) on lipid bilayers containing purified LFA-1, ICAM-1, and the transmembrane and glycophosphatidylinositol isoforms of LFA-3. LGLs moved at 8 microns/min on ICAM-1 but poorly (less than 1 microns/min) on its receptor pair LFA-1. TM-LFA-3 promoted locomotion at a rate close to ICAM-1, whereas the cells were less motile on GPI-LFA-3. The difference in the rates of locomotion on the two isoforms of LFA-3 is presumably attributable to their difference in anchoring and lateral mobility in the bilayer. In spite of the variation in motility the ultrastructure of the adhering cells was similar on all four ligands. LGLs contacted the membrane variably, i.e., cells adhering only in a few small areas or in larger areas were detected on each ligand. The ...
TY - JOUR. T1 - Hydrodynamic interaction between overlapping domains during recurrence of registration within planar lipid bilayer membranes. AU - Han, Tao. AU - Bailey, Trevor P.. AU - Haataja, Mikko. PY - 2014/3/26. Y1 - 2014/3/26. N2 - Due to a thermodynamic coupling between the two leaflets comprising a lipid bilayer, compositional lipid domains residing within opposing leaflets are often found in registry. If the system is perturbed by displacing one domain relative to the other, diffusive and advective lipid fluxes are established to restore equilibrium and reestablish domain overlap. In this work, we focus on the advective part of the process, and first derive an analytical expression for the hydrodynamic drag coefficient associated with the advective flow for the special case of perfect domain overlap. The resulting expression identifies parameter regions where sliding friction between the leaflets dominates over viscous dissipation within the leaflets or vice versa. It is shown that in ...
The data here provides the raw data for the calculations of radial distribution functions, hydrogen bond analysis, lateral lipid diffusion and lipid tail order parameters. This raw data was generated using tools from the CPPTRAJ analysis package which is freely available with the AmberTools program (https://ambermd.org/AmberTools.php). The data presented here shows how two drug molecules (propofol and fentanyl) alter the physical and mechanical properties of DOPC and DPPC lipid bilayers, and for the first time, how a general anesthetic and an opioid analgesic/anesthetic differ in their interactions with phospholipid membranes, by direct comparison. Understanding the differences between opioid and anesthetic interactions with phospholipid bilayers will lead to a more complete understanding of general anesthesia at the molecular level ...
Detailed understanding of lipid bilayers are of tremendous importance due to their role in many biological processes. This Thesis focuses on structural and dynamical properties of lipid bilayers and their interactions with locally acting anesthetics, studied by Molecular Dynamics simulations.. The effect of dehydration of a lipid bilayer is a biologically important phenomenon which was investigated by detailed examination of a number of structural and dynamical lipid parameters at different levels of hydration. The result shows that whereas the structural properties of the bilayer only moderately depend on the degree of hydration, the dynamics of the system is affected very strongly.. Related to changes in the bilayer caused by hydration are structural and dynamical changes caused by the presence of anesthetics. Lidocaine is a common, locally acting anesthetic that interacts with lipid bilayers. The difference in position, orientation and diffusional behavior for charged and uncharged lidocaine ...
Lipid bilayers constitute one of the critical parts of all biological membranes, including cell membranes. A nice description of lipid bilayers and their function in biological membranes can be found here. They can be exceptionally complex and contain hundreds of different constituents, so simpler model lipid bilayers are often produced in the laboratory and studied experimentally. They form closed spheroidal structures, called liposomes, with a thickness of a few nm, and characteristic linear dimensions up to several microns. Larger such structures are usually called Giant Unilamellar Vesicles, or GUVs. Why should we care about these structures as mechanicians? For a number of reasons, the elastic properties of lipid membranes are thought to play a crucial role in governing their potential configurations. Recent experimental studies of the role of membrane curvature on domain formation in biomembranes, for example, provide testament to this notion. Images of their work are reproduced (with ...
Lipid bilayers constitute one of the critical parts of all biological membranes, including cell membranes. A nice description of lipid bilayers and their function in biological membranes can be found here. They can be exceptionally complex and contain hundreds of different constituents, so simpler model lipid bilayers are often produced in the laboratory and studied experimentally. They form closed spheroidal structures, called liposomes, with a thickness of a few nm, and characteristic linear dimensions up to several microns. Larger such structures are usually called Giant Unilamellar Vesicles, or GUVs. Why should we care about these structures as mechanicians? For a number of reasons, the elastic properties of lipid membranes are thought to play a crucial role in governing their potential configurations. Recent experimental studies of the role of membrane curvature on domain formation in biomembranes, for example, provide testament to this notion. Images of their work are reproduced (with ...
We investigate the structural changes to lipid membrane that ensue from the addition of aliphatic alcohols with various alkyl tail lengths. Small angle neutron diffraction from flat lipid bilayers that are hydrated through water vapor has been employed to eliminate possible artefacts of the membrane curvature and the alcohols membrane-water partitioning. We have observed clear changes to membrane structure in both transversal and lateral directions. Most importantly, our results suggest the alteration of the membrane-water interface. The water encroachment has shifted in the way that alcohol loaded bilayers absorbed more water molecules when compared to the neat lipid bilayers. The experimental results have been corroborated by molecular dynamics simulations to reveal further details. Namely, the order parameter profiles have been fruitful in correlating the mechanical model of structural changes to the effect of anesthesia.
We present optical observations of phase separation in mixed model membranes in the form of giant unilamellar vesicles. These observations are compared to the phase behavior of lipid mixtures, which we determined by X-ray scattering and differential scanning calorimetry or extracted from the existing literature. The domain properties are affected not only by the bulk phase behavior but also by the membrane lamellarity and phase transition pathways. These observations have important implications for how phase behavior determined by bulk methods using dense, multilamellar lipid bilayers are linked to phase separation in giant, unilamellar lipid bilayers as observed by microscopy ...
Detecting ligand-receptor binding on cell membrane surfaces is required to understand their function and behavior. Detection platforms can also provide an avenue for the development of medical devices and sensor biotechnology. The use of fluorescence techniques for such purposes is highly desirable as they provide high sensitivity. Herein, we describe a technique that utilizes the sensitivity of fluorescence without directly tagging the analyte of interest to monitor ligand-receptor interactions on supported lipid bilayers. The fluorescence signal is modulated according to the charge state of the target analyte. The binding event elicits protonation or deprotonation of pH-responsive reporter dyes embedded in the lipid bilayer. Supported lipid membranes containing ortho-conjugated rhodamine B-POPE (1-hexadecanoyl-2-(9Z-octadecenoyl)-sn-glycero-3-phosphoethanolamine), which fluoresces in its protonated but not in its deprotonated form, were utilized as sensor platforms for biotin-avidin and biotin
Williams, Alan John 1984. The measurement of cardiac membrane channels following their incorporation into planar phospholipid bilayers. In: Harris, P.C. ed ...
The perturbation of model lipid bilayer vesicles by halogenated hydrocarbons was investigated to determine if cellular membrane damage could be evaluated and used as a screening technique for toxicity. A fluorescent probe of 1-anilino-8-naphthalene-sulfonate (82768) (ANS) was bound to synthetic phospholipid vesicles prepared from egg lecithin and dimyristoyl-phosphatidyl-choline (DML). The fluores
This study evaluates the use of the planar lipid bilayer as a functional assay of Ca(2+)-activated K+ channel activity for use in purification of the channel protein. Ca(2+)-activated K+ channels from the plasma membrane of an insulin-secreting hamster Beta-cell line (HIT T15) were incorporated into planar lipid bilayers. The single channel conductance was 233 picoSiemens (pS) in symmetrical 140 mmol/l KCl and the channel was strongly K(+)-selective (PCl/PK = 0.046; PNa/PK = 0.027). Channels incorporated into the bilayer with two orientations. In 65% of cases, the probability of the channel being open was increased by raising calcium on the cis side of the bilayer (to which the membrane vesicles were added) or by making the cis side potential more positive. At a membrane potential of + 20 mV, which is close to the peak of the Beta-cell action potential, channel activity was half-maximal at a Ca2+ concentration of about 15 mumol/l. Charybdotoxin greatly reduced the probability of the channel being open
The influenza M2 protein not only forms a proton channel but also mediates membrane scission in a cholesterol-dependent manner to cause virus budding and release. The atomic interaction of cholesterol with M2, as with most eukaryotic membrane proteins, has long been elusive. We have now determined the cholesterol-binding site of the M2 protein in phospholipid bilayers using solid-state NMR spectroscopy. Chain-fluorinated cholesterol was used to measure cholesterol proximity to M2 while sterol-deuterated cholesterol was used to measure bound-cholesterol orientation in lipid bilayers. Carbon-fluorine distance measurements show that at a cholesterol concentration of 17 mol%, two cholesterol molecules bind each M2 tetramer. Cholesterol binds the C-terminal transmembrane (TM) residues, near an amphipathic helix, without requiring a cholesterol recognition sequence motif. Deuterium NMR spectra indicate that bound cholesterol is approximately parallel to the bilayer normal, with the rough face of the sterol
Using a high throughput screen, we have identified a family of 12-residue long peptides that spontaneously translocate across membranes. These peptides function by a poorly understood mechanism that is very different from that of the well-known, highly cationic cell penetrating peptides such as the tat peptide from HIV. The newly discovered translocating peptides can carry polar cargoes across synthetic bilayers and across cellular membranes quickly and spontaneously without disrupting the membrane. Here we report on the biophysical characterization of a representative translocating peptide from the selected family, TP2, as well as a negative control peptide, ONEG, from the same library. We measured the binding of the two peptides to lipid bilayers, their secondary structure propensities, their dispositions in bilayers by neutron diffraction, and the response of the bilayer to the peptides. Compared to the negative control, TP2 has a greater propensity for membrane partitioning, although it ...
The capability of lipid bilayers to exhibit fluid-phase behavior is a fascinating property, which enables, for example, membrane-associated components, such as lipids (domains) and transmembrane proteins, to diffuse within the membrane. These diffusion processes are of paramount importance for cells, as they are for example involved in cell signaling processes or the recycling of membrane components, but also for recently developed analytical approaches, which use differences in the mobility for certain analytical purposes, such as in-membrane purification of membrane proteins or the analysis of multivalent interactions. Here, models describing the Brownian motion of membrane inclusions (lipids, peptides, proteins, and complexes thereof) in model bilayers (giant unilamellar vesicles, black lipid membranes, supported lipid bilayers) are summarized and model predictions are compared with the available experimental data, thereby allowing for evaluating the validity of the introduced models. It will be
In this article, we investigate fluid-gel transformations of a DPPC lipid bilayer in the presence of nanoparticles, using coarse grained molecular dynamics. Two types of nanoparticles are considered, specifically a 3 nm hydrophobic nanoparticle located in the core of the bilayer and a 6 nm charged nanoparticle located at the interface between the bilayer and water phase. Both negatively and positively charged nanoparticles at the bilayer interface are investigated. We demonstrate that the presence of all types of nanoparticles induces disorder effects in the structure of the lipid bilayer. These effects are characterized using computer visualization of the gel phase in the presence of nanoparticles, radial distribution functions, and order parameters. The 3 nm hydrophobic nanoparticle immersed in the bilayer core and the positively charged nanoparticle at the bilayer surface have no effect on the temperature of the fluid-gel transformation, compared to the bulk case. Interestingly, a negatively ...
1. Wagner ML, Tamm LK (2000) Tethered polymer-supported planar lipid bilayers for reconstitution of integral membrane proteins: silane-polyethyleneglycol-lipid as a cushion and covalent linker. Biophys J 79: 1400-1414.. 2. Sackmann E (1996) Supported membranes: scientific and practical applications. Science 271: 43-48.. 3. Richter RP, Berat R, Brisson AR (2006) Formation of solid-supported lipid bilayers: an integrated view. Langmuir 22: 3497-3505.. 4. Kusters I, Mukherjee N, de Jong MR, Tans S, Koçer A, et al. (2011) Taming Membranes: Functional Immobilization of Biological Membranes in Hydrogels. PLoS ONE 6(5): e20435. doi:10.1371/journal.pone.0020435. 5. Schuler, M. A., Denisov, I. G., Sligar, S. G. (2013) Nanodiscs as a new tool to examine lipid-protein interactions. Methods Mol Biol. 974, 415-433.. 6. Sloan, C. D., Marty, M. T., Sligar, S. G., Bailey, R. C. (2013) Interfacing lipid bilayer nanodiscs and silicon photonic sensor arrays for multiplexed protein-lipid and protein-membrane ...
Read Examining the Origins of the Hydration Force Between Lipid Bilayers Using All-Atom Simulations, The Journal of Membrane Biology on DeepDyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
Several techniques to assemble artificial lipid bilayers involve the zipping of monolayers. Their efficiency is determined by the renewal of the saturated monolayers to be zipped and this proceeds by adsorption of lipids dispersed in oil as aggregates. The size of these lipids aggregates is a key parameter to ensure both the stability of the suspension and a fast release of lipids at the interface. We propose a new method inspired from the solvent-shifting nucleation process allowing to control and tune the lipid aggregates size and that improves the production of artificial membranes. It is simpler and faster than current methods starting from a dry lipid film, which are highly sensitive to environmental conditions. This method opens the route to bilayer production processes with new potentialities in membrane composition.
Recently, the transfer method has been shown to be useful for preparing cell-sized phospholipid bilayer vesicles, within which desired substances at desired concentrations can be encapsulated, with a desired asymmetric lipid composition. Here, we investigated the transfer process of water-in-oil (W/O) droplets coat 2013 Hot Papers
A novel solid-state NMR technique for identifying the asymmetric insertion depths of membrane proteins in lipid bilayers is introduced. By applying Mn2+ ions on the outer but not the inner leaflet of lipid bilayers, the sidedness of protein residues in the lipid bilayer can be determined through paramagnetic relaxation enhancement (PRE) effects. Protein-free lipid membranes with one-side Mn2+-bound surfaces exhibit significant residual 31P and lipid headgroup 13C intensities, in contrast to two-side Mn2+-bound membranes, where lipid headgroup signals are mostly suppressed. Applying this method to a cell-penetrating peptide, penetratin, we found that at low peptide concentrations, penetratin is distributed in both leaflets of the bilayer, in contrast to the prediction of the electroporation model, which predicts that penetratin binds to only the outer lipid leaflet at low peptide concentrations to cause an electric field that drives subsequent peptide translocation. The invalidation of the ...
Advances in Planar Lipid Bilayers and Liposomes, Volume 6, continues to include invited chapters on a broad range of topics, covering both main arrangements...
Purchase Advances in Planar Lipid Bilayers and Liposomes, Volume 5 - 1st Edition. Print Book & E-Book. ISBN 9780123736871, 9780080466545
Lipid bilayers form the boundaries of the cell and its organelles. Many physiological processes, such as cell movement and division, involve bending and folding of the bilayer at high curvatures. Currently, bending of the bilayer is treated as an elastic deformation, such that its stress-strain response is i
TY - JOUR. T1 - Vibrational layer eigenmodes of binary phospholipid-cholesterol bilayers at low temperatures. AU - Leonov, D. V.. AU - Adichtchev, S. V.. AU - Dzuba, S. A.. AU - Surovtsev, N. V.. PY - 2019/2/22. Y1 - 2019/2/22. N2 - Raman spectra in the low-frequency spectral range - between 5 and 90cm-1 - were studied for multilamellar bilayers prepared with cholesterol (Chol) and phospholipids of three different types: doubly unsaturated lipids 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), monounsaturated lipids 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and fully saturated lipids 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). The narrow peak seen below 250 K and positioned between 9 and 18cm-1 - depending on the system and temperature - was attributed to the vibrational eigenmode of a lipid monolayer. For the DOPC-Chol bilayer, the peak position and the peak width were found to monotonically increase and decrease, respectively, with the Chol concentration. For POPC-Chol ...
We will discuss the physics that governs the lipid localization and domain formation in multicomponent lipid bilayers coupled to an elastic substrate. Lipid localization and domain formation has been studied extensively in biological cell membranes. In this talk we will extend a previous model for membrane energetics to account for the coupling between the bending and the local lipid composition of the two leaflets. Our aim is to determine the relationship between the localization and domain formation in the presence of lipid flip-flops between the two leaflets and the effect of intrinsic curvature of the lipids. Using a lattice model for the membrane, we simulate the system and study the effect of lipid flip-flop on lipid organization in the membrane. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2012.MAR.B41.15. ...
Progress with respect to enrichment and separation of native membrane components in complex lipid environments, such as native cell membranes, has so far been very limited. The reason for the slow progress can be related to the lack of efficient means to generate continuous and laterally fluid supported lipid bilayers (SLBs) made from real cell membranes. We show in this work how the edge of a hydrodynamically driven SLB can be used to induce rupture of adsorbed lipid vesicles of compositions that typically prevent spontaneous SLB formation, such as vesicles made of complex lipid compositions, containing high cholesterol content or being derived from real cell membranes. In particular, upon fusion between the moving edge of a preformed SLB and adsorbed vesicles made directly from 3T3 fibroblast cell membranes, the membrane content of the vesicles was shown to be efficiently transferred to the SLB. The molecular transfer was verified using cholera toxin B subunit (CTB) binding to monosialoganglioside
O:13:\PanistOpenUrl\:36:{s:10:\\u0000*\u0000openUrl\;N;s:6:\\u0000*\u0000idc\;N;s:6:\\u0000*\u0000fmt\;s:7:\journal\;s:6:\\u0000*\u0000doi\;s:0:\\;s:6:\\u0000*\u0000pii\;s:0:\\;s:7:\\u0000*\u0000pmid\;s:0:\\;s:9:\\u0000*\u0000atitle\;s:111:\THEORY OF SPIN-LATTICE RELAXATION IN LIPID BILAYERS AND BIOLOGICAL MEMBRANES. 2H AND 14N QUADRUPOLAR ...
The transport of palmitic acid (PA) across planar lipid bilayer membranes was measured using a high specific activity [14C]palmitate as tracer for PA. An all-glass trans chamber was employed in order to minimize adsorbance of PA onto the surface. Electrically neutral (diphytanoyl phosphatidylcholine) and charged (Azolectin) planar bilayers were maintained at open electric circuit. We found a permeability to PA of (8.8 +/- 1.9) x 10(-6) cm s(-1) (n = 15) in neutral and of (10.3 +/- 2.2) x 10(-6) cm s(-1) (n = 5) in charged bilayers. These values fall within the order of magnitude of those calculated from desorption constants of PA in different vesicular systems. Differences between data obtained from planar and vesicular systems are discussed in terms of the role of solvent, radius of curvature, and pH changes. ...
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Lipid bilayers are unique soft materials operating in general in the low Reynolds limit. While their shape is predominantly dominated by curvature elasticity as in a solid shell, their in-plane behavior is that of a largely inextensible viscous fluid. Furthermore, lipid membranes are extremely responsive to chemical stimuli. Because in their biological context they are continuously brought out-of-equilibrium mechanically or chemically, it is important to understand their dynamics. Here, we introduce Onsagers variational principle as a general and transparent modeling tool for lipid bilayer dynamics. We introduce this principle with elementary examples, and then use it to study the sorption of curved proteins on lipid membranes.. Link to Chapter ...
One of the key lockers to understand mechanisms of biological action of drugs and natural compounds is their capacity to incorporate/cross lipid bilayer membranes. In the light of demanding experimental techniques, in silico molecular modelling has become a powerful alternative to tackle these issues. In the past few years, molecular dynamics (MD) has opened many perspectives, providing an atomistic description of the related intermolecular interactions. Using MD simulations, we have explored the capacity of several compounds (polyphenols, vitamins E and C, plantazolicin, carprofens) to incorporate lipid bilayer membranes. The different compounds were chosen according to their different biological functions, namely (i) antioxidant activity against lipid peroxidation, (ii) antimicrobial activity with the possibility of trans-membrane pore formation, and (iii) inhibition of enzymes involved in Alzheimers disease. In order to rationalize their mechanisms of action, their position and orientation in
Terminal lipophilization of a unique DNA dodecamer by various nucleolipid headgroups: Their incorporation into artificial lipid bilayers and hydrodynamic properties
9] L. Movileanu, D. Popescu, S. I. Popescu, Transbilayer pores induced by thickness fluctuations, Bull. Math. Biol. 68 (2006) 1231-1255. V. Zhelev, D. Needham, Tension-stabilized pores in giant vesicles: Determination of pore size and pore line tension, Biochim. Biophys. Acta 1147 (1993) 89-104. [11] M. Winterhalter, W. Helfrich, Effect of voltage on pores in membranes, Phys. Rev. A 36 (1987) 5874-5876. Random Processes in the Appearance and Dynamics of an Electropore 33 [12] E. Neumann, M. Schaefer-Ridder, Y. Frey, Polymorphism of monolayers of monomeric and macromolecular lipids: On the defect structure of crystalline phases and the possibility of hexatic order formation in physics of amphiphilic layers, in: J. Meunier, D. Langevin, V. ), Physics of amphiphilic layers, Springer, Berlin (1987). [43] M. Langner, H. Pruchnik, K. Kubica, The effect of the lipid bilayer state on fluorescence intensity of fluorescein-PE in a saturated lipid bilayer, Z. Naturforsch. 55 (2000) 418-424. [44] K. Kubica, ...
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Supplementary MaterialsSupplementary Information 41598_2017_4219_MOESM1_ESM. in lipid bilayers. Additionally, the DNP sensitivity-enhanced two-dimensional 13C/13C chemical shift correlations via proton AUY922 inhibition driven spin diffusion offered length constraints to characterize protein-lipid interactions and uncovered the transmembrane topology of cytochrome b5. The outcomes reported in this research would pave methods for high-quality structural and topological investigations of membrane-bound full-duration bitopic proteins complexes under physiological circumstances. Launch Bitopic membrane proteins with an KI67 antibody individual membrane-spanning -helix represent over fifty percent of most membrane proteins, which contain approximately 1 / 3 of all open up reading frames (ORFs), in individual AUY922 inhibition genomes1C3. Their dynamic protein-proteins and protein-ligand interactions in the membrane environment play various vital functions in the cellular procedures connected with ...
Biological membranes mainly constituent lipid molecules along with some proteins and steroles. The properties of the pure lipid bilayers as well as in the presence of other constituents (in case of two or three component systems) are very important to be studied carefully to model these systems and compare them with the realistic systems. Molecular dynamic simulations provide a good opportunity to model such systems and to study them at microscopic level where experiments fail to do. In this thesis we study the structural and dynamic properties of the pure phospholipid bilayers and the phase behavior of phospholipid bilayers when other constituents are present in them. Material and structural properties like area per lipid and area compressibility of the phospholipids show a big scatter in experiments. These properties are studied for different system sizes and it was found that the increasing undulations in large systems effect these properties. A correction was applied to area per lipid and ...
Proteins and lipids are the building blocks of biological membranes. In the past and at present, only the lipids in the form of bilayers, vesicles, and thin films found/find applications in...
Cholesterol, due to its condensing effect, is considered an important regulator of membrane thickness. Other sterols, due to their structural similarities to cholesterol, are often assumed to have a universal effect on membrane properties similar to the condensing effect of cholesterol, albeit possibly to different degrees. We used x-ray diffraction to investigate this assumption. By the combination of lamellar diffraction and grazing-angle scattering, we measured the membrane thickness and the tilt-angle distribution of the lipids hydrocarbon chains. This method is sensitive to phase separation, which is important for examining the miscibility of sterols and phospholipids. Mixtures of ergosterol or cholesterol with dimyristoylphosphatidylcholine, palmitoyloleoylphosphatidylcholine, and dioleoylphosphatidylcholine were systematically studied. We found that mixing ergosterol with phospholipids into a single phase became increasingly difficult with higher sterol concentrations and also with ...
This thesis deals with the study of lipid bilayer systems by solid-state nuclear magnetic resonance. Two-dimensional 1H-13C separated local field experiments under magic-angle spinning were employed to investigate structural and dynamical modifications of cell membranes, resulting from the addition of compounds with some biological relevance. For further interpretation of the segmental order obtained from the 2D experiments other methods, such as 31P-NMR, 2H-NMR and molecular dynamics simulations, were also employed. The work presented in this thesis can be divided into two parts. The first part refers to the setup of experimental conditions. Heating and hydration effects were addressed in order to define both the temperature of the system as well as the number of water molecules per lipid necessary to fully hydrate the bilayer. Application of this experimental setup to lipid membrane systems with biological relevance constitutes the second part. The interaction of monogalactosyl- ...
Biological membranes do not only occur as planar bilayer structures, but bilayers have also been shown to, depending on the lipid composition, curve into intriguing 3D structures. Understanding the biological implication as well as the application of such interfaces, for e.g. drug delivery and other biomedical application, requires the development of well-defined model system.. We have shown that spin-coating the constituting lipids followed by hydration of the lipid layer can be used to form non-lamellar liquid crystalline surfaces of different types on the surface. In order to make the layers more responsive polymer micro-gels with a diameter of about 55 nm can be embedded within the layer. Another way to for non-planar lipid interfaces are to deposit lipids on nanostructured surfaces. Here we demonstrate the formation of fluid supported bilayers on vertical gallium phosphide nanowire (NW) forests using self-assembly from lipid vesicular dispersions.1 The phospholipid mixture used had a ...
The combined effects of the tendency of cholesterol to order lipids in the liquid phase and the coupling between lipids in the two leaves of a bilayer are investigated theoretically utilizing a Landau free energy. We show that as a consequence of these combined effects, lateral phase separation in the outer leaf between cholesterol-rich and -poor liquids causes a similar, but weaker, phase separation in the inner leaf. Just as the areal density of lipids in the outer leaf increases in the cholesterol-rich regions, so the areal density of lipids also increases in the inner leaf. Thus, the areal density in the inner leaf varies spatially, reflecting spatial variations of the areal density in the outer leaf. This provides a mechanism for proteins attached to the inner leaf via a hydrocarbon tether to respond to variations in the composition of the outer leaf. We also note that the effect of coupling between the leaves should be observable in artificial bilayers.. ...
The combined effects of the tendency of cholesterol to order lipids in the liquid phase and the coupling between lipids in the two leaves of a bilayer are investigated theoretically utilizing a Landau free energy. We show that as a consequence of these combined effects, lateral phase separation in the outer leaf between cholesterol-rich and -poor liquids causes a similar, but weaker, phase separation in the inner leaf. Just as the areal density of lipids in the outer leaf increases in the cholesterol-rich regions, so the areal density of lipids also increases in the inner leaf. Thus, the areal density in the inner leaf varies spatially, reflecting spatial variations of the areal density in the outer leaf. This provides a mechanism for proteins attached to the inner leaf via a hydrocarbon tether to respond to variations in the composition of the outer leaf. We also note that the effect of coupling between the leaves should be observable in artificial bilayers.. ...
TY - JOUR. T1 - Diffusion limitation in the block by symmetric tetraalkylammonium ions of anthrax toxin channels in planar phospholipid bilayer membranes. AU - Blaustein, Robert O.. AU - Finkelstein, Alan. PY - 1990/11. Y1 - 1990/11. N2 - Current flow through the channel formed in planar phospholipid bilayer membranes by the PA65 fragment of anthrax toxin is blocked, in a voltage-dependent manner, by tetraalkylammonium ions (at micromolar concentrations), which bind to a blocking site within the channel lumen. We have presented evidence that diffusion plays a significant role in the kinetics of blocking by tetrabutylammonium ion (Bu4N+) from the cis (toxin-containing) side of the membrane (Blaustein, R. O., E. J. A. Lea, and A. Finkelstein. 1990. J. Gen. Physiol. 96:921-942); in this paper we examine the implications and consequences of diffusion control for binding kinetics. As expected for a diffusion-affected reaction, both the entry rate constant (k1cis) of Bu4N+ from the cis solution to the ...
Experimental and computational studies have indicated that hydrophobicity plays a key role in driving the insertion of transmembrane alpha-helices into lipid bilayers. Molecular dynamics simulations allow exploration of the nature of the interactions of transmembrane alpha-helices with their lipid bilayer environment. In particular, coarse-grained simulations have considerable potential for studying many aspects of membrane proteins, ranging from their self-assembly to the relation between their structure and function. However, there is a need to evaluate the accuracy of coarse-grained estimates of the energetics of transmembrane helix insertion. Here, three levels of complexity of model system have been explored to enable such an evaluation. First, calculated free energies of partitioning of amino acid side chains between water and alkane yielded an excellent correlation with experiment. Second, free energy profiles for transfer of amino acid side chains along the normal to a phosphatidylcholine
The effects of the insecticide lindane on the phase transition in multilamellar bilayers of saturated diacylphosphatidylcholines of different acyl chain length (DC14PC, DC16PC, and DC18PC) have been studied by means of differential scanning calorimetry (DSC), as well as computer-simulation calculations on a molecular interaction model. The calorimetric data show that increasing concentrations of lindane lower the transition temperature and lead to a broadening of the specific heat in a systematic way depending on the lipid acyl chain length. Kinetic effects in the observed calorimetric traces indicate that the incorporation of lindane into multilamellar lipid bilayers is slow, but faster for the shorter lipid species. Large unilamellar vesicles do not show such kinetic effects. The transition enthalpy is for all three lipid species found to be independent of the lindane concentration which implies that the entropy of mixing is vanishingly small. This lends support to a microscopic molecular ...
TY - JOUR. T1 - Lipid fluorination enables phase separation from fluid phospholipid bilayers. AU - Webb, S. J.. AU - Greenway, K.. AU - Bayati, M.. AU - Trembleau, Laurent Alain Claude. PY - 2006/5. Y1 - 2006/5. N2 - To probe the effect of lipid fluorination on the formation of lipid domains in phospholipid bilayers, several new fluorinated and non-fluorinated synthetic lipids were synthesised, and the extent of phase separation of these lipids from phospholipid bilayers of different compositions was determined. At membrane concentrations as low as 1% mol/mol, both fluorinated and non-.uorinated lipids were observed to phase separate from a gel-phase ( solid ordered) phospholipid matrix, but bilayers in a liquid disordered state caused no phase separation; if the gel-phase samples were heated above the transition temperature, then phase separation was lost. We found incorporation of perfluoroalkyl groups into the lipid enhanced phase separation, to such an extent that phase separation was ...
The assembly of nucleic acid nanostructures with controlled size and shape has large impact in the fields of nanotechnology, nanomedicine and synthetic biology. The directed arrangement of nano-structures at interfaces is important for many applications. In spite of this, the use of laterally mobile lipid bilayers to control RNA three-dimensional nanostructure formation on surfaces remains largely unexplored. Here, we direct the self-assembly of RNA building blocks into three-dimensional structures of RNA on fluid lipid bilayers composed of cationic 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or mixtures of zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) and cationic sphingosine. We demonstrate the stepwise supramolecular assembly of discrete building blocks through specific and selective RNA-RNA interactions, based on results from quartz crystal microbalance with dissipation (QCM-D), ellipsometry, fluorescence recovery after photobleaching (FRAP) and total internal reflection
Progress in theoretical modelling (our group has performed molecularly detailed self-consistent field (SCF) calculations on lipid bilayer membranes) in combination with advanced and cutting-edge techniques have enabled us to perform more advanced experiments on lipid bilayers. This makes it possible to determine on how lipids and other membrane constituents organise the delicate force balances in bilayers that are responsible for the structure and structural (in)stability.. The aim of this PhD project is to develop an experimental membrane platform to determine mechanical properties and topological integrity of lipid membranes of increasing complexity. The experimental platform comprises of a supported double lipid membrane in a flow cell, mounted in a set-up including a TIRF microscope and an AFM dedicated to force measurements. The influence of various perturbing stimuli, such as edge-active agents, antimicrobial peptides and nanoparticles, on these membrane properties will be investigated. ...
TY - JOUR. T1 - Assembly of α-synuclein aggregates on phospholipid bilayers. AU - Lv, Zhengjian. AU - Hashemi, Mohtadin. AU - Banerjee, Siddhartha. AU - Zagorski, Karen. AU - Rochet, Jean Christophe. AU - Lyubchenko, Yuri L.. N1 - Funding Information: The work at the University of Nebraska Medical Center (UNMC) was supported by grants from the National Institutes of Health to Y.L.L. ( R01 GM096039 , R01GM118006 and R21 NS101504 ). J.C.R. was supported by the Branfman Family Foundation . M.H. was partially supported by the UNMC Graduate Fellowship. The computational modeling was partially performed using resources at the Holland Computing Center of the University of Nebraska, which receives support from the Nebraska Research Initiative . Anton 2 computer time was provided by the Pittsburgh Supercomputing Center (PSC) through Grant R01GM116961 from the National Institutes of Health. The Anton 2 machine at PSC was generously made available by D.E. Shaw Research. The authors thank Melody A. ...
HYPOTHESIS It is known that nanoparticles (NPs) in a biological fluid are immediately coated by a protein corona (PC), composed of a hard (strongly bounded) and a soft (loosely associated) layers, which represents the real nano-interface interacting with the cellular membrane in vivo. In this regard, supported lipid bilayers (SLB) have extensively been used as relevant model systems for elucidating the interaction between biomembranes and NPs. Herein we show how the presence of a PC on the NP surface changes the interaction between NPs and lipid bilayers with particular care on the effects induced by the NPs on the bilayer structure. EXPERIMENTS In the present work we combined Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D) and Neutron Reflectometry (NR) experimental techniques to elucidate how the NP-membrane interaction is modulated by the presence of proteins in the environment and their effect on the lipid bilayer. FINDINGS Our study showed that the NP-membrane interaction is
Lipid bilayers are important in biological cells. They are the basis of cell membranes, and they surround most cell organelles. Lipid bilayers form automatically from phospholipids by self-assembly. The phospholipids have heads which mix with water and tails which reject water. So the tails come together in the centre of the double layer, and the heads on the outside are surrounded by water. The lipid bilayers stop most water-soluble (hydrophilic) molecules passing through. They also stop most ions. In cells, proteins are put in the bilayer by enzymes. The proteins decide which molecules come in and which go out of the cell. For example, cells control salt concentrations and pH by pumping ions across their membranes using proteins called ion pumps. ...
Planar solid-supported membranes based on amphiphilic block copolymers represent promising systems for the artificial creation of structural surfaces. Here we introduce a method for engineering functional planar solid-supported membranes through insertion of active biomolecules. We show that membranes based on poly(dimethylsiloxane)-block-poly(2-methyl-2-oxazoline) (PDMS-b-PMOXA) amphiphilic diblock copolymers, which mimic natural membranes, are suitable for hosting biomolecules. Our strategy allows preparation of large-area, well-ordered polymer bilayers via Langmuir-Blodgett and Langmuir-Schaefer transfers, and insertion of biomolecules by using Bio-Beads. We demonstrate that a model membrane protein, the potassium channel from the bacterium Mesorhizobium loti, remains functional after insertion into the planar solid-supported polymer membrane. This approach can be easily extended to generate a platform of functional solid-supported membranes by insertion of different hydrophobic biomolecules, ...
Descrição: We establish and quantify correlations among the molecular structures, interaction forces, and physical processes associated with light-responsive self-assembled surfactant monolayers or bilayers at interfaces. Using the surface forces apparatus (SFA), the interaction forces between adsorbed monolayers and bilayers of an azobenzene-functionalized surfactant can be drastically and controllably altered by light-induced conversion of trans and cis molecular conformations. These reversible conformation changes affect significantly the shape of the molecules, especially in the hydrophobic region, which induces dramatic transformations of molecular packing in self-assembled structures, causing corresponding modulation of electrostatic double layer, steric hydration, and hydrophobic interactions. For bilayers, the isomerization from trans to cis exposes more hydrophobic groups, making the cis bilayers more hydrophobic, which lowers the activation energy barrier for (hemi)fusion. A ...
TY - JOUR. T1 - Chiral Recognition of Lipid Bilayer Membranes by Supramolecular Assemblies of Peptide Amphiphiles. AU - Sato, Kohei. AU - Ji, Wei. AU - Álvarez, Zaida. AU - Palmer, Liam C.. AU - Stupp, Samuel I.. PY - 2019/6/10. Y1 - 2019/6/10. N2 - On the basis of the exclusive existence of homochirality in biomolecules and the well-known phenomenon of chiral recognition, it is obvious that chirality is a crucial factor in biological events. We report here that supramolecular assemblies of peptide amphiphiles interact with lipid bilayer membranes in a stereospecific manner. When negatively charged chiral phospholipid bilayer vesicles were subjected to the assemblies, we found that peptide amphiphiles with l-amino acids show stronger affinity for the liposomes compared to the ones with d-amino acids. To examine their biological functions, we tested the cytotoxicity of nanofibers against mammalian primary cells using human bone marrow mesenchymal stem cells and murine astroglial cells. We ...
Klughammer, B., Benz, B., Betz, M., Thume, M., & Dietz, K. - J. (1992). Reconstitution of vacuolar ion channels into planar lipid bilayers. Biochimica et Biophysica Acta, 1104(2), 308-316. doi:10.1016/0005-2736(92)90045- ...
The authors have studied microstructure evolution during thermally induced phase separation in a class of binary supported lipid bilayers using a quantitative application of imaging ellipsometry. The bilayers consist of binary mixtures consisting of a higher melting glycosphingolipid, galactosylceramide (GalCer), which resides primarily in the outer leaflet, and a lower melting, unsaturated phospholipid, 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC). Three different bilayer compositions of GalCer/DLPC mixtures at 35:65, 20:80, and 10:90 molar ratios were cooled at controlled rates from their high-temperature homogeneous phase to temperatures corresponding to their phase coexistence regime and imaged in real time using imaging ellipsometry. During the thermotropic course of GalCer gelation, we find that two distinct types of morphological features modulate. First, the formation and growth of chain and fractal-like defects ascribed to the net change in molecular areas during the phase transition. The
TY - JOUR. T1 - Theory of modulated phases in lipid bilayers and liquid crystal films. AU - Chen, C. M.. AU - MacKintosh, F. C.. N1 - Copyright: Copyright 2017 Elsevier B.V., All rights reserved.. PY - 1996. Y1 - 1996. N2 - We present a general theory for equilibrium-modulated phases of chiral and achiral bilayer membranes and liquid crystal films. Both bulk smectics as well as freely suspended films are considered. For flexoelectric systems, continuous structural phase transitions are predicted among square-lattice, hexagonal, and distorted two-dimensional modulated phases as a function of the applied electric field. It is also shown that only uniform flat phases are predicted for thin films. One-dimensional ripple phases and two-dimensional square-lattice phases can occur with increasing film thickness.. AB - We present a general theory for equilibrium-modulated phases of chiral and achiral bilayer membranes and liquid crystal films. Both bulk smectics as well as freely suspended films are ...
TY - JOUR. T1 - Impact of cholesterol on voids in phospholipid membranes. AU - Falck, E.. AU - Patra, M.. AU - Karttunen, M.E.J.. AU - Hyvönen, M.T.. AU - Vattulainen, I.. PY - 2004. Y1 - 2004. N2 - Free volume pockets or voids are important to many biological processes in cell membranes. Free volume fluctuations are a prerequisite for diffusion of lipids and other macromolecules in lipid bilayers. Permeation of small solutes across a membrane, as well as diffusion of solutes in the membrane interior are further examples of phenomena where voids and their properties play a central role. Cholesterol has been suggested to change the structure and function of membranes by altering their free volume properties. We study the effect of cholesterol on the properties of voids in dipalmitoylphosphatidylcholine (DPPC) bilayers by means of atomistic molecular dynamics simulations. We find that an increasing cholesterol concentration reduces the total amount of free volume in a bilayer. The effect of ...
TY - JOUR. T1 - Durability of oxygen evolution of photosystem II incorporated into lipid bilayers. AU - Noji, Tomoyasu. AU - Kondo, Masaharu. AU - Kawakami, Keisuke. AU - Shen, Jian Ren. AU - Nango, Mamoru. AU - Dewa, Takehisa. PY - 2014/11. Y1 - 2014/11. N2 - Photosystem II (PSII) has attracted a lot of attention for use in the construction of artificial photosynthetic materials due to its high activity of oxidation of water molecules. However, the robustness of PSII needs to be improved for in vitro application. In this study, we incorporated PSII (Thermosynechococcus vulcanus) into various phospholipid membranes to examine the activity and durability of oxygen evolution. PSII was incorporated into anionic 1,2-dioleoyl-sn-glycero-3-phospho-(1-rac-glycerol) (PSII-DOPG), zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphocholine (PSII-DOPC), and cationic 1,2-dioleoyl-sn-glycero-3-ethylphosphocholine (PSII-EDOPC). Structural integrity of PSII was examined by absorption and fluorescence spectroscopy. ...
We investigated the thermotropic phase behavior of the distearoylphosphatidylcholine (DSPC)-cholesterol binary bilayer membrane as a function of the cholesterol composition (X(ch)) by fluorescence spectroscopy using 6-propionyl-2-(dimethylamino)naphthalene (Prodan) and differential scanning calorimetry (DSC). The fluorescence spectra, each of which has a single maximum, showed that the wavelength at the maximum intensity (lambda(max)) changed depending on the bilayer state: ca. 440 nm for the lamellar gel (L(beta) or L(beta)) and the liquid ordered (L(o)) phases, ca. 470 nm for the ripple gel (P(beta)) phase and ca. 490 nm for the liquid crystalline (L(alpha)) phase, respectively. The transition temperatures were determined from the temperature dependences of the lambda(max) and endothermic peaks of the DSC thermograms. Both measurements showed that the pretransition disappears around X(ch)=0.035. The constructed temperature-X(ch) phase diagram indicated that the phase behavior of the binary ...
Carbohydrate-protein interactions play a major-role in recognition of cells by external macromolecules. Single saccharide ligands, however, bind only weakly to their protein receptors. Sufficient affinity is achieved by appropriate mutual orientation of the saccharide epitopes and their protein receptors, which allows multiple simultaneous interactions. In other words, high affinity binding is achieved through multivalency, where the high number of simultaneous binding events compensates the lack of strength of an individual interaction. Solid-supported methods allowing synthesis of multiantennary glycoconjugates have, hence, been under active development. The present paper is a review of the solid-phase protocols useful for preparation of glycoconjugates. ...
Effects of hydrostatic pressure on the molecular structure and endothermic phase transitions of phosphatidylcholine bilayers: a Raman scattering study
The effects of the cholesterol analog 5α-cholestan-3β-ol-6-one (6-ketocholestanol) on bilayer structure, bilayer cohesive properties, and interbilayer repulsive pressures have been studied by a combination of X-ray diffraction, pipette aspiration, and dipole potential experiments. It is found that 6-ketocholestanol, which has a similar structure to cholesterol except with a keto moiety at the 6 position of the B ring, has quite different effects than cholesterol on bilayer organization and cohesive properties. Unlike cholesterol, 6-ketocholestanol does not appreciably modify the thickness of liquid-crystalline egg phosphatidylcholine (EPC) bilayers, and causes a much smaller increase in bilayer compressibility modulus than does cholesterol. These data imply that 6-ketocholestanol has both its hydroxyl and keto moieties situated near the water-hydrocarbon interface, thus making its orientation in the bilayer different from cholesterols Keywords: ...
TY - JOUR. T1 - Asymmetric phospholipid. T2 - Lipopolysaccharide bilayers; a Gram-negative bacterial outer membrane mimic. AU - Clifton, Luke A.. AU - Skoda, Maximilian W. A.. AU - Daulton, Emma L.. AU - Hughes, Arwel V.. AU - Le Brun, Anton P.. AU - Lakey, Jeremy. H.. AU - Holt, Stephen A.. PY - 2013/12/6. Y1 - 2013/12/6. N2 - The Gram-negative bacterial outer membrane (OM) is a complex and highly asymmetric biological barrier but the small size of bacteria has hindered advances in in vivo examination of membrane dynamics. Thus, model OMs, amenable to physical study, are important sources of data. Here, we present data from asymmetric bilayers which emulate the OM and are formed by a simple two-step approach. The bilayers were deposited on an SiO2 surface by Langmuir-Blodgett deposition of phosphatidylcholine as the inner leaflet and, via Langmuir-Schaefer deposition, an outer leaflet of either Lipid A or Escherichia coli rough lipopolysaccharides (LPS). The membranes were examined using ...
abstract = Monoterpenes are abundant in essential oil extracted from plants. These relatively small and hydrophobic molecules have shown many important biological fucntions, including antimicrobial activity and membrane penetration enhancement. The interaction between the monoterpenes and lipid bilayers is considered important to the understanding of the biological functions of monoterpenes. In this study we investigate the effect of cyclic and linear monoterpenes on the structure and dynamics of lipids in model membrane. We study the ternary system 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) - monoterpene - water as a model with a focus on dehydrated conditions. By combining complementary techniques, including differential scanning calorimetry (DSC), solid-state nuclear magnetic resonance (ss NMR) and small and wide angle X-ray scattering (SAXS and WAXS), bilayer structure, phase transitions and lipid molecular dynamics are investigated at different water contents. Monoterpenes cause ...
P.838 right column 3rd paragraph: The number of all phospholipid and cholesterol molecules per vesicle was calculated to be approximately 7000 and 5600, respectively, with hexosylceramides and gangliosides making only a relatively minor contribution (Table 2). Considering that a single phospholipid molecule occupies a space of approximately 65 Å^2 (0.65 nm^2) (primary source), 7000 phospholipids would build a planar bilayer of 4550 nm^2, i.e., 50% of the outer and inner surfaces of a vesicle possessing an outer diameter of 42 nm ...
Biological membranes define not only the cell boundaries but any compartment within the cell. To some extent, the functionality of membranes is related to the elastic properties of the lipid bilayer and the mechanical and hydrophobic matching with functional membrane proteins. Supported lipid bilayers (SLBs) are valid biomimetic systems for the study of membrane biophys-ical properties. Here, we acquired high-resolution topographic and quantitative mechanics data of phase-separated SLBs using a recent atomic force microscopy (AFM) imaging mode based on force measurements. This technique allows us to quantitatively map at high resolution the mechanical differences of lipid phases at different loading forces. We have applied this approach to evaluate the contribution of the underlying hard support in the determination of the elastic properties of SLBs and to determine the adequate indentation range for obtaining reliable elastic moduli values. At ~200 pN, elastic forces dominated the force-indentation
A study of voltage fluctuations in bilayer lipid membranes during electroporation and under current-clamp conditions is presented. Qualitative considerations based on the electroporation theory are used in order to explain the phenomenon on long time scale. Indeed, the current-clamp condition induces a feedback mechanism on the pore formation and therefore on the macroscopic conductance. Voltage fluctuations can thus be recorded. These fluctuations are nonstationary long-living and have a flicker power spectrum over nearly four decades of frequency between about 10-2 and 102Hz. The study of the fluctuations in the time domain has been performed by introducing an electrical model of the system formed by the membrane and the circuit under current-clamp configuration. The analysis of the time series gives a characteristic time of 100ms for the circuitry response to the fragments of electroporation signals with characteristic times faster than 100ms. During electroporation, the response to an ...
Page contains details about PLGA nanocapsules coated with phosphatidylcholine bilayer . It has composition images, properties, Characterization methods, synthesis, applications and reference articles : nano.nature.com
Two-dimensional gel electrophoresis was used to identify heat-modifiable outer membrane proteins, which were candidates for porins, from Helicobacter pylori membrane preparations. Four such proteins with apparent molecular masses of 48, 49, 50, and 67 kDa were isolated. The four proteins copurified together after selective detergent solubilizations followed by anion-exchange chromatography, and each protein was ultimately purified to homogeneity by gel purification. These proteins were then tested for pore-forming ability with a planar lipid bilayer model membrane system. All four proteins appeared to be present as monomers, and they formed pores with low single-channel conductances in 1.0 M KCl of 0.36, 0.36, 0.30, and 0.25 nS, respectively, for the 48-, 49-, 50-, and 67-kDa proteins which we propose to designate HopA, HopB, HopC, and HopD. N-terminal amino acid sequence analyses showed a high degree of homology among all four proteins, and it appears that these proteins constitute a family of ...
We explore this process through modeling the wrapping of a spherical particle by a model bilayer membrane, using coarse-grained molecular dynamics simulations and a theoretical elastic model. Specifically, we study the kinetics and morphologies of wrapping as a function of the relevant system parameters, including the particle radius, the strength of the membrane-particle interaction, and the membrane bending rigidity. The theoretical model predicts a phase diagram as a function of the system parameters, which is compared to results of the dynamics simulations ...
Dive into the research topics of Softening of membrane bilayers by detergents elucidated by deuterium NMR spectroscopy. Together they form a unique fingerprint. ...
Over the last 25 years one of us (WKS) has been investigating physical properties of lipid bilayer membranes. In 1991 a group led by WKS was organized into the Laboratory of Structure and Dynamics of Biological Membranes, the effective member of which is AW. Using mainly the electron paramagnetic resonance (EPR) spin-labeling method, we obtained unexpected results, which are significant for the better understanding of the functioning of biological membranes. We have developed a new pulse EPR spin-labeling method for the detection of membrane domains and evaluation of lipid exchange rates. This review will be focused on our main results which can be summarized as follows: (1) Unsaturation of alkyl chains greatly reduces the ordering and rigidifying effects of cholesterol although the unsaturation alone gives only minor fluidizing effects, as observed by order and reorientational motion, and rather significant rigidifying effects, as observed by translational motion of probe molecules; (2) ...
The interaction between lipid bilayers in water has been intensively studied over the last decades. Osmotic stress was applied to evaluate the forces between two approaching lipid bilayers in aqueous solution. The force-distance relation between lipid mono- or bilayers deposited on mica sheets using a surface force apparatus (SFA) was also measured. Lipid stabilised foam films offer another possibility to study the interactions between lipid monolayers. These films can be prepared comparatively easy with very good reproducibility. Foam films consist usually of two adsorbed surfactant monolayers separated by a layer of the aqueous solution from which the film is created. Their thickness can be conveniently measured using microinterferometric techniques. Studies with foam films deliver valuable information on the interactions between lipid membranes and especially their stability and permeability. Presenting inverse black lipid membrane (BLM) foam films supply information about the properties of ...
The interaction between lipid bilayers in water has been intensively studied over the last decades. Osmotic stress was applied to evaluate the forces between two approaching lipid bilayers in aqueous solution. The force-distance relation between lipid mono- or bilayers deposited on mica sheets using a surface force apparatus (SFA) was also measured. Lipid stabilised foam films offer another possibility to study the interactions between lipid monolayers. These films can be prepared comparatively easy with very good reproducibility. Foam films consist usually of two adsorbed surfactant monolayers separated by a layer of the aqueous solution from which the film is created. Their thickness can be conveniently measured using microinterferometric techniques. Studies with foam films deliver valuable information on the interactions between lipid membranes and especially their stability and permeability. Presenting inverse black lipid membrane (BLM) foam films supply information about the properties of ...
Phospholipids are essential building blocks of biological membranes. Despite a vast amount of very accurate experimental data, the atomistic resolution structures sampled by the glycerol backbone and choline headgroup in phoshatidylcholine bilayers are not known. Atomistic resolution molecular dynamics simulations have the potential to resolve the structures, and to give an arrestingly intuitive interpretation of the experimental data, but only if the simulations reproduce the data within experimental accuracy. In the present work, we simulated phosphatidylcholine (PC) lipid bilayers with 13 different atomistic models, and compared simulations with NMR experiments in terms of the highly structurally sensitive C-H bond vector order parameters. Focusing on the glycerol backbone and choline headgroups, we showed that the order parameter comparison can be used to judge the atomistic resolution structural accuracy of the models. Accurate models, in turn, allow molecular dynamics simulations to be used as an
Discrete-continuous hybrid models are a popular means for describing elastic membrane-mediated particle interactions in and on lipid bilayers. Here, the continuous part is usually given by an approximation of the lipid membrane by an infinitely thin and sufficiently smooth hypersurface, whose elastic energy is determined by a Canham-Helfrich type functional. The discrete component results from modeling non-membrane particles as rigid discrete entities, which, depending on their configuration, induce local constraints on the membrane along the membrane-particle interfaces. In this context, the interaction potential describes the optimal elastic energy of such hybrid systems with a fixed particle configuration. Correspondingly, the energy minimization principle yields that stationary particle configurations are given by the local minima of the interaction potential. The main goal of this work is the proof of differentiability of the interaction potential for a selected class of models. This is ...
Abstract The capsaicin and mustard oil receptors TRPV1 and TRPA1, respectively, are highly expressed in polymodal nociceptors, ubiquitous thin nerve fibers that can evoke pain and induce neurogenic inflammation by neuropeptide secretion. Reversible oxidation of intracellular cysteine residues of these channel proteins causes activation and sensitization to adequate stimuli. The ion channel activity can be assessed in cultured sensory neurons, transfected cell lines, and in artificial lipid bilayers, using patch-clamp recording, calcium microfluorimetry, and indirectly by single-fiber recording and enzyme immunoassay measurement of stimulated neuropeptide (CGRP) release from isolated organ preparations. Strikingly, we found that ordinary blue light (405 nm) activates human TRPA1 and evokes pain in white human skin. This results from the ubiquitous presence of the heme precursor protoporphyrin IX (Pp IX) that acts as a chromophore to produce singlet oxygen under illumination. The ensuing ...
Abstract: Droplet interface bilayers are a convenient model system to study the physio-chemical properties of phospholipid bilayers, the major component of the cell membrane. The mechanical response of these bilayers to various external mechanical stimuli is an active area of research due to implications for cellular viability and development of artificial cells. In this manuscript we characterize the separation mechanics of droplet interface bilayers under step strain using a combination of experiments and numerical modeling. Initially, we show that the bilayer surface energy can be obtained using principles of energy conservation. Subsequently, we subject the system to a step strain by separating the drops in a step wise manner, and track the evolution of the bilayer contact angle and radius. The relaxation time of the bilayer contact angle and radius, along with the decay magnitude of the bilayer radius were observed to increase with each separation step. By analyzing the forces acting on the ...
The study of membrane proteins (MPs) remains a major challenge in protein biochemistry mainly because of problems of protein aggregation and thermal instability in nonnative preparations of MPs in detergents, or native-like but insoluble preparations in liposomes. As a result, nonconventional surfactants with properties intermediate to lipids and detergents are becoming increasingly popular as alternative platforms for MPs (Bayburt and Sligar, 2002; Boldog et al., 2006; Park et al., 2007; Dalal et al., 2009; Popot, 2010). Discoidal lipoproteins, which include reconstituted high-density lipoprotein particles, nanodiscs, and nanoscale apolipoprotein-bound bilayers (NABBs), constitute a type of nonconventional platform that has enabled novel assays on MPs sequestered in a well-defined, soluble native-like lipid environment, such as single-particle imaging, surface plasmon resonance, nuclear magnetic resonance, and surface-enhanced infrared absorption spectroscopy (Banerjee et al., 2008; Das et al., ...
Abstract: The activity of antimicrobial peptides stems from their interaction with bacterial membranes, which are disrupted according to a number of proposed mechanisms. Here, we investigate the interaction of a model antimicrobial peptide that contains a single arginine residue with vesicles containing model lipid membranes. The surfactant-like peptide Ala6-Arg (A6R) is studied in the form where both termini are capped (CONH-A6R-NH2, capA6R) or uncapped (NH2-A6R-OH, A6R). Lipid membranes are selected to correspond to model anionic membranes (POPE/POPG) resembling those in bacteria or model zwitterionic membranes (POPC/DOPC) similar to those found in mammalian cells. Viable antimicrobial agents should show activity against anionic membranes but not zwitterionic membranes. We find, using small-angle X-ray scattering (SAXS) and cryogenic-TEM (transmission electron microscopy) that, uniquely, capA6R causes structuring of anionic membranes due to the incorporation of the peptide in the lipid bilayer ...
Fingerprint Dive into the research topics of The structure and stability of phospholipid bilayers by atomic force microscopy. Together they form a unique fingerprint. ...
The specific activity of Ca2+-ATPase reconstituted into diC18 : 1PC bilayers decreases at molar ratios C12NO : PC , 2where mixed rod-like (cylindrical) C12NO + diC18 : 1PC micelles (r , 1) are formed ). The geometry of the surfactant + phospholipid aggregates consisting of two compo- nents depends on the effective molecular packing parameter . The theory predicts that, depending on the packing parameter d, molecules form spherical micelles (d , 0.33),normal cylindrical micelles (0.33 , d , 0.5), curved bilayers (0.5 , d , 1), flat bilayers (d = 1) or inverted micelles (d , 1). We conclude that the inhibition of Ca2+-ATPase observed in diC18 : 1PC bilayers is most probably caused by C12NO:PC (mol:mol) a severe deformation of the bilayer resulting in the formation of Fig. 5. Dependences of the specific Ca2+-ATPase activity A at 37 normal tubular mixed C12NO + diC18 : 1PC micelles in isola- thickness (SANS parameter dg) of the diC18 : 1PC bilayer (?), SANS tion (d , 0.5). A decrease of the activity ...
Lipid bilayer. Diagram of the arrangement of amphipathic lipid molecules to form a lipid bilayer. The yellow polar head groups ... Phospholipids forming lipid vesicles. Lipid vesicles or liposomes are circular pockets that are enclosed by a lipid bilayer.[22 ... are not consistent with a lipid bilayer as they lack a bilayer and do not consist of lipids.[45] Rather, the structure has an ... and extracellular faces of the resulting bilayer. This forms a continuous, spherical lipid bilayer. Hydrophobic interactions ( ...
Lipid bilayer. Diagram of the arrangement of amphipathic lipid molecules to form a lipid bilayer. The yellow polar head groups ... are not consistent with a lipid bilayer as they lack a bilayer and do not consist of lipids.[48] Rather, the structure has an ... Lipid vesicles or liposomes are approximately spherical pockets that are enclosed by a lipid bilayer.[24] These structures are ... The cell membrane consists of a lipid bilayer, including cholesterols (a lipid component) that sit between phospholipids to ...
Experimental system, dioleoylphosphatidylcholine bilayers. The hydrophobic hydrocarbon region of the lipid is ~30 Å (3.0 nm) as ... "Structure of Fluid Lipid Bilayers". Blanco.biomol.uci.edu. 2009-11-10. Retrieved 2019-10-09. ... and of proteins within lipid bilayers.[citation needed] During assembly of the bacteriophage (phage) T4 virion, the ... Protein-lipid complexes: lipoprotein. The biomacromolecular complexes are studied structurally by X-ray crystallography, NMR ...
2001). Lipid bilayers : structure and interactions ; with 6 tables. Berlin [u.a.]: Springer. ISBN 978-3540675556. Stryer, ... In turn, phospholipids and cholesterol interact noncovalently in order to form the lipid bilayer. This reaction may be depicted ... Biology portal Technology portal Lipids Phospholipid bilayer Nucleotides DNA DNA replication Proteinogenic amino acid Codon ... which in turn incorporate noncovalent interactions to form the lipid bilayer. Fatty acid chains are found in two major ...
Ionophores in Planar Lipid Bilayers". Cell physiology sourcebook: essentials of membrane biophysics (Fourth ed.). London, UK. ...
This allows particles protruding from the lipid bilayer to be trapped and studied. Hydrodynamic trapping can be used on a more ... Hydrodynamic trapping can also be used to trap and study molecules in lipid bilayers. This is done using hydrodynamic drag ... Hydrodynamic trapping of molecules in lipid bilayers. PNAS 2012 109 (26) 10328-10333. Michael Kühn, Helge Stanjek, Stefan ... are created by a fluid flow through a very small cone shaped pipet located about one micrometer away from the lipid bilayer. ...
The structure of melittin in lipid bilayers. Biochim. Biophys. Acta., 1979; 555, 371-373. Dufton MJ and Hider RC. Snake toxin ... The interaction of bee melittin with lipid bilayer membranes. Biochim. Biophys. Acta., 1978; 510, 75-86. Drake AF and Hider RC ... The composition of black lipid membranes formed from egg-yolk lecithin, cholesterol and n-decane. Biochimica Biophysica Acta., ... The effect of synthetic polymers on the electrical and permeability properties of lipid membranes. Biochim. Biophys. Acta., ...
... farther from the interior of the lipid bilayer, in order to maintain their energetically favorable interaction with water. This ... "Hydrophobic Mismatch between Helices and Lipid Bilayers". Biophysical Journal. Biophysical Society. 84 (1): 379-385. Bibcode: ... When hydrophobic mismatch occurs, WALPs are known to tilt in the bilayer. The extent of this tilt is affected up to a certain ... point by an entropy contribution that arises from the helix's presence in the bilayer and then by more specific helix-lipid ...
Planar Lipid Bilayers (BLMs) and Their Applications. 7. Elsevier. pp. 723-734. doi:10.1016/s0927-5193(03)80050-5. Iosub R, ... Koulen P (January 2003). "Chapter 26 - Using bilayer lipid membranes to investigate the pharmacology of intracellular calcium ...
This achievement inspired Daniel to use the solid-supported lipid bilayers to separate membrane-bound species via ... Specifically, Daniel worked on solid-supported lipid bilayers. She showed that an artificial glycocalyx-like nanostructure ... She is interested in the role of membrane lipids in biological interactions, with a focus on how viruses interact with cell ... Cell membranes contain a variety of proteins and biomolecules, which are held within a matrix of lipid phases. Daniel believes ...
DNA ion channels: Burns, JR; Stulz, E; Howorka, S (12 June 2013). "Self-assembled DNA nanopores that span lipid bilayers". Nano ... on the DNA-lipid interface as no central channel lumen is present in the design that lets ions pass across the lipid bilayer. ... then demonstrated that such a DNA-induced toroidal pore can facilitate rapid lipid flip-flop between the lipid bilayer leaflets ... This indicated that the DNA-induced lipid pore has a toroidal shape, rather than cylindrical, as lipid headgroups reorient to ...
Windrem, David A.; Plachy, William Z. (1980). "The diffusion-solubility of oxygen in lipid bilayers". Biochimica et Biophysica ... Lipids and Lipid Metabolism. 1345 (3): 293-305. doi:10.1016/S0005-2760(97)00005-2. Zigangirova, Naylia A.; Morgunova, Elena Y ... lipids provide a more favorable environment for O2 solubility than in aqueous mediums.By protecting lipids from free-radical ... Gordon, Gerald B.; Barcza, Maureen A.; Bush, Marilyn E. (1977). "Lipid Accumulation in Hypoxic Tissue Culture Cells". The ...
Their ability to form oligomeric pores in artificial lipid bilayers has been documented but the physiological significance of ... The colicins similarly form pores in lipid bilayers. Structural homology therefore suggests that Bcl-2 family members that ... A direct interaction of Bcl-2 with bilayer-reconstituted purified VDAC was demonstrated, with Bcl-2 decreasing channel ...
Lichtenberg D, Ahyayauch H, Goñi FM (2013). "The mechanism of detergent solubilization of lipid bilayers". Biophysical Journal ... Solubilization of cell membrane bilayers requires a detergent that can enter the inner membrane monolayer. Advancements in the ...
Alattia JR, Shaw JE, Yip CM, Privé GG (October 2006). "Direct visualization of saposin remodelling of lipid bilayers". Journal ... The role of Saposin C is not known; however, it is shown to bind both the lysosomal membrane and the lipid moieties of GluCer, ... The two aliphatic chains of glucocerebroside may remain associated with the lysosomal bilayer or interact with the activating ... GCase requires the activating protein Saposin C as well as negatively charged lipids for maximal catalytic activity. ...
What is unique about intramembrane proteases is that their active sites are buried in the lipid bilayer of cell membranes, and ... The active site of rhomboid protease is protected laterally from the lipid bilayer by its six constituent transmembrane helices ... Lemberg MK, Freeman M (December 2007). "Cutting proteins within lipid bilayers: rhomboid structure and mechanism". Molecular ... can occur in the hydrophobic environment of a lipid bilayer: one of the central mysteries of intramembrane proteases. The ...
"Parvovirus B19 VLP recognizes globoside in supported lipid bilayers". Virology. 456-457: 364-369. doi:10.1016/j.virol.2014.04. ...
"On the flexibility of hydrocarbon chains in lipid bilayers". Journal of the American Chemical Society. 93 (20): 5017-22. doi: ... Deuterated polyunsaturated fatty acids, such as linoleic acid, slow down the chain reaction of lipid peroxidation that damage ... August 2012). "Small amounts of isotope-reinforced polyunsaturated fatty acids suppress lipid autoxidation". Free Radical ... in deuterium-labelled lipid molecules can be quantified using solid state deuterium NMR. Deuterium NMR spectra are especially ...
Lipid bilayer Transmembrane protein Patch clamp Pore-forming toxin Krasilnikov, Oleg Vladimirovich. Protein channels in the ... reconstituted in planar lipid bilayers (principally α-staphylotoxin because of its unique ability to recognize polymer ... "The ionic channels formed by cholera toxin in planar bilayer lipid membranes are entirely attributable to its B-subunit". ... "Protein channels in a lipid bilayer" from Moscow State University of the Russian Academy of Sciences (1983). Krasilnikov began ...
The membrane is a lipid bilayer. The glycogen that is found within the glycosome is identical to glycogen found freely in the ... For parasites, ether-lipid synthesis is vital to be able to complete its life cycle, making the enzymes protected by the ... These enzymes are those associated with ether-lipid synthesis or the beta oxidation of certain fatty acids. Cells without ... These processes include glycolysis, purine salvage, beta oxidation of fatty acids, and ether lipid synthesis. The main function ...
Bock JB, Scheller RH (October 1999). "SNARE proteins mediate lipid bilayer fusion". Proc. Natl. Acad. Sci. U.S.A. 96 (22): ...
The polar chlorine disrupts lipid bilayers and could increase permeability. When chlorohydrin formation occurs in lipid ... "Modification of red cell membrane lipids by hypochlorous acid and haemolysis by preformed lipid chlorohydrins". Redox Report : ... Hypochlorous acid reacts with unsaturated bonds in lipids, but not saturated bonds, and the ClO− ion does not participate in ... Stoichiometry and NMR analysis". Chemistry and Physics of Lipids. 78 (1): 55-64. doi:10.1016/0009-3084(95)02484-Z. PMID 8521532 ...
Lipid bilayers of biological membranes, however, are barriers for ions. This is why energy can be stored as a combination of ...
... in a bilayer such as a cell membrane. Lipid bilayers occur when hydrophobic tails line up against one another, forming a ... They can form lipid bilayers because of their amphiphilic characteristic. In eukaryotes, cell membranes also contain another ... so proteins and lipid molecules are then free to diffuse laterally through the lipid matrix and migrate over the membrane. ... as through the study of lipid polymorphism it is now known that the behaviour of lipids under physiological (and other) ...
Their amphipathic nature drives the formation of the lipid bilayer structure of membranes. The cell membrane seen under the ... These are important components for the formation of lipid bilayers. Phosphatidylethanoamines, phosphatidylcholines, and other ... Phosphatidates Phosphatidates are lipids in which the first two carbon atoms of the glycerol are fatty acid esters, and the 3 ... They are usually organized into a bilayer in membranes with the polar hydrophilic heads sticking outwards to the aqueous ...
"Osh4p exchanges sterols for phosphatidylinositol 4-phosphate between lipid bilayers". J. Cell Biol. 195 (6): 965-78. doi: ... and a C-terminal lipid transport domain (ORD). The PH domain binds the trans-Golgi membrane by contacting the lipid PI4P and ... OSBP is a lipid transfer protein that controls cholesterol/PI4P exchange at ER-Golgi membrane contact sites. 25- ... OSBP is the founding member of the ORP (OSBP-related proteins) family of lipid transfer proteins. Mammals have 16 different ...
Lipoplexes are liposome structures characterized by a bilayer lipid membrane. Lastly, micelles result from electrostatic ... These four major types of nanoparticles are all nonionic lipids. Nonionic lipids are safe, nontoxic and biocompatible. ... Lipid nanoparticles (LNPs) are being considered for delivering siRNA to silence AR. The most effective LNP to be found in vivo ... "Lipid nanoparticle siRNA systems for silencing the androgen receptor in human prostate cancer in vivo". International Journal ...
Positions of the proteins are calculated using an implicit solvation model of the lipid bilayer. The results of calculations ... The calculated spatial arrangements of the lower resolution protein structures in the lipid bilayer can be found in other ... Lomize, AL; Pogozheva, ID; Mosberg, HI (2011). "Anisotropic solvent model of the lipid bilayer. 2. Energetics of insertion of ... Lomize, AL; Pogozheva, ID; Mosberg, HI (2011). "Anisotropic solvent model of the lipid bilayer. 1. Parameterization of long- ...
Mycobacteria have an outer membrane lipid bilayer. If a Gram stain is performed, MTB either stains very weakly "Gram-positive" ... The high lipid content of this pathogen accounts for many of its unique clinical characteristics. It divides every 16 to 20 ... or does not retain dye as a result of the high lipid and mycolic acid content of its cell wall. MTB can withstand weak ...
The transfer of an ion from water to a nonpolar medium with dielectric constant of ~3 (lipid bilayer) or 4 to 10 (interior of ... On the other hand, this model can be successfully applied for describing transfer from water to the fluid lipid bilayer. More ... However, the dielectric properties of proteins and lipid bilayers are much more similar to those of nonpolar solvents than to ... Lomize AL, Pogozheva ID, Mosberg HI (Apr 2011). "Anisotropic solvent model of the lipid bilayer. 2. Energetics of insertion of ...
Voltage sensitive ion channels are glycoprotein molecules which extend through the lipid bilayer, allowing ions to traverse ...
Other proteins and lipids can be added to the cell membrane. By these changes, the cell can adjust what it brings in or puts ... The membrane is made up of a thin layer called the 'phospholipid bilayer'. This has two layers of phospholipid molecules with ... Transmission electron microscope (TEM) image of a lipid vesicle. The two dark bands around the edge are the two leaflets of the ... bilayer. Historically, similar images confirmed that the cell membrane is a bilayer ...
Deamer and Branton demonstrated that the freeze-etch method split the lipid bilayer of membranes to reveal integral proteins ... His advisor was David Cornwell, a lipid biochemist, so Deamer focused on calcium interactions with fatty acid and phospholipid ... Deamer, D.W.; Branton, D. (1967). "Fracture planes in an ice-bilayer model membrane system". Science. 158 (3801): 655-657. ... and in 1985 Deamer demonstrated that the Murchison carbonaceous meteorite contained lipid-like compounds that could assemble ...
Type V proteins are anchored to the lipid bilayer through covalently linked lipids. Finally Type VI proteins have both ... Integral monotopic proteins are associated with the membrane from one side but do not span the lipid bilayer completely. ... Proteins that cross the membrane are surrounded by annular lipids, which are defined as lipids that are in direct contact with ... The part of the protein that is embedded in the hydrophobic regions of the bilayer are alpha helical and composed of ...
Bottom: 9, lipid bilayer of bacteria and eukaryotes; 10, lipid monolayer of some archaea. ... Ether-linked lipids, pseudopeptidoglycan. Ester-linked lipids, peptidoglycan. Ester-linked lipids, various structures. ... In ester lipids this is an ester bond, whereas in ether lipids this is an ether bond. Ether bonds are chemically more resistant ... In some archaea, the lipid bilayer is replaced by a monolayer. In effect, the archaea fuse the tails of two phospholipid ...
Haines TH (2001). "Do sterols reduce proton and sodium leaks through lipid bilayers?". Prog. Lipid Res. 40 (4): 299-324. doi: ... මූලික ලිපියන්: hypercholesterolemia සහ lipid hypothesis. According to the lipid hypothesis, abnormally high cholesterol levels ... Christie, W. W. (2003). Lipid analysis. PJ Barnes and associates. පිටු 416. ISBN 0-9531949-5-7. ... Recently, cholesterol has also been implicated in cell signaling processes, assisting in the formation of lipid rafts in the ...
... while the hydrophobic regions are within the phospholipid bilayer of the cell membrane. The cell membrane consists of lipids ... The main constituents of the general molecular composition of the cell includes: proteins and lipids which are either free ...
The retroviral envelope serves three distinct functions: protection from the extracellular environment via the lipid bilayer, ... Envelope: composed of lipids (obtained from the host plasma membrane during the budding process) as well as glycoprotein ...
... could produce the chemical components of proteins and lipids, alongside those of RNA.[98][99] The researchers used the term " ... "Common origins of RNA, protein and lipid precursors in a cyanosulfidic protometabolism". Nature Chemistry. 7 (4): 301-7. ... "Common origins of RNA, protein and lipid precursors in a cyanosulfidic protometabolism". Nature Chemistry. 7 (4): 301-7. ... reactions involving the compound diamidophosphate which could have linked the chemical components into short peptide and lipid ...
... and the bacteria collapse into very large spheres surrounded by a single lipid bilayer. The membrane can then be analyzed on a ...
The anchoring on a GPI raft in the lipid bilayer supports claims of an extracellular scaffolding function.[16] ...
Cholesterol stimulates both the insertion of anandamide into synthetic lipid monolayers and bilayers, and its transport across ... are non-charged lipids that readily cross lipid membranes.[1][2][3][4][5] However, since the endocannabinoids are water ... The Journal of Lipid Research. 46 no. (8): 1652-1659. doi:10.1194/jlr.M400498-JLR200. PMID 15930521.. ... Chemistry and Physics of Lipids. 134 (2): 131-139. doi:10.1016/j.chemphyslip.2004.12.010. PMID 15784231.. ...
The most common mechanism for activation and regulation of molecules beneath the lipid bilayer is via reversible tyrosine ...
... versus PA on membrane curvature by measuring the effect these have on the transition temperature of PE from lipid bilayers to ... many lipid-binding proteins are cytosolic and localise to the membrane by binding only the headgroups of lipids. Perhaps the ... "Profiling membrane lipids in plant stress responses. Role of phospholipase D alpha in freezing-induced lipid changes in ... because DAG is the precursor for so many other lipids, it too is soon metabolised into other membrane lipids. This means that ...
Type 2 rhodopsin (rainbow colored) embedded in a lipid bilayer (heads red and tails blue) with transducin below it. Gtα is ...
"Rule of thumb" for the area per molecule in lipid bilayer". BioNumbers. Retrieved 2011-10-09.. ...
Calculated orientations of cytochromes c in the lipid bilayer ...
Membrane lipids. The most common red blood cell membrane lipids, schematically disposed as they are distributed on the bilayer ... Simply put, this lipid bilayer is composed of cholesterol and phospholipids in equal proportions by weight. The lipid ... The red blood cell membrane comprises a typical lipid bilayer, similar to what can be found in virtually all human cells. ... Additionally, the activity of many membrane proteins is regulated by interactions with lipids in the bilayer. ...
... bilayer) bisa leuwih badag. ... Lipid. Gambar 1: Struktur lipid. Loba lipid nu diwangun ku ... Buntut nonpolar lipid (U) ngagunduk jadi lipid lapis ganda (1) atawa misél (2). Hulu polarna (P) nyanghareup ka lingkungan ... Istilah lipid ngawengku rupa-rupa molekul, malah kaasup sanyawaan nu rélatif teu leyur na cai atawa nonpolar nu asalna tina ... Lipid loba mibanda ciri polar ti antara lolobana ciri nonpolarna. Umumna, guruntulan strukturna mah nonpolar atawa hidrofobik ...
... forming nano-scale spherical structures made of a lipopolysaccharide-rich lipid bilayer enclosing periplasmic materials, and ...
An example of a biological semi-permeable membrane is the lipid bilayer, on which is based on the plasma membrane that ... The phospholipid bilayer is most permeable to small, uncharged solutes. Protein channels float through the phospholipids, and, ... the phospholipid bilayer is a semipermeable membrane that is very specific in its permeability. The hydrophilic phosphate heads ...
Transport vesicles are small structures within the cell consisting of a fluid enclosed by a lipid bilayer that hold cargo. ...
Other types of aggregates can also be formed, such as spherical or cylindrical micelles or lipid bilayers. The shape of the ... They disorganize the membrane's lipid bilayer (SDS, Triton X-100, X-114, CHAPS, DOC, and NP-40), and solubilize proteins. ... "The Lipid Chronicles. 11 November 2011. Archived from the original on 26 April 2012. Retrieved 1 August 2012.. ... Prolonged exposure to surfactants can irritate and damage the skin because surfactants disrupt the lipid membrane that protects ...
The process by which lipids in a phospholipid bilayer membrane move from one side of the membrane to the other, facilitated by ...
Tapping mode imaging is gentle enough even for the visualization of supported lipid bilayers or adsorbed single polymer ...
Membrane lipids. *Lipid bilayer. *Phospholipids. *Lipoproteins. *Sphingolipids. *Sterols. Membrane proteins. *Membrane ...
"Bilayer thickness determines the alignment of model polyproline helices in lipid membranes". Physical Chemistry Chemical ... and this secondary structure does not traverse lipid membranes in natural conditions. In 2018, a group of researcher from ...
These subunits are attached to the target cells, the way we have already explained, and extend the lipid bilayer, forming the ... Å in width that provides a surface complementary to the nonpolar portion of the lipid bilayer. The interfaces are composed of ... Hemolysins or haemolysins are lipids and proteins that cause lysis of red blood cells by disrupting the cell membrane. Although ... One way hemolysin lyses erythrocytes is by forming pores in phospholipid bilayers.[3][4] Other hemolysins lyse erythrocytes by ...
... tinggi dibandingkan dengan bakteri gram negatif terkait dengan perubahan struktur membran selnya yang mengandung lipid bilayer. ...
It contains long intracellular loops (ICLs or ICD) connecting the TMDs that extend beyond the lipid bilayer into the cytoplasm ... ATP hydrolysis may widen the periplasmic opening and push the substrate towards the outer leaflet of the lipid bilayer. ... Since the lipid cannot be stable for a long time in the chamber environment, lipid A and other hydrophobic molecules may "flip ... The membrane-spanning region of the ABC transporter protects hydrophilic substrates from the lipids of the membrane bilayer ...
RasMol Cutaway Views of Lipid Bilayers. Jump to image list below. Many aspects of these images were optimized for discerning ... the structures of the bilayers. The palmitic and oleic tails are given slightly different hues to help in discerning their ...
Membrane lipids: …each forming half of a bilayered wall. A bilayer is composed of two sheets of phospholipid molecules with all ... In a water medium, the phospholipids of the two sheets align so that their water-repellent, lipid-soluble tails are turned and… ... Other articles where Lipid bilayer is discussed: cell: ... In lipid: Glycerophospholipids. …common of which is the bilayer ... In lipid: Lipids in biological membranes. …a continuous bimolecular leaflet, or bilayer. The polar portions of the constituent ...
Semipermeable lipid bilayers exhibit diastereoselectivity favoring ribose Message Subject (Your Name) has sent you a message ... Semipermeable lipid bilayers exhibit diastereoselectivity favoring ribose. M. G. Sacerdote and J. W. Szostak ... Effect of polyols on the DMPC lipid monolayers and bilayers. Iwona Budziak, Marta Arczewska, Monika Sachadyn-Król, Arkadiusz ... Permeability of drugs and hormones through a lipid bilayer: insights from dual-resolution molecular dynamics ...
However, there are limitations to these systems and recently a class of new systems in which the lipid bilayer is supported on ... To study aspects of cellular membranes in a controlled manner, solid supported planar bilayers have served as reliable tools ... Here, we review the different polymer cushioned bilayer systems and discuss their manufacture and advantages. ... Lipid bilayers are some of the most fascinating self-assembled structure in living nature. Not only do they serve as the ...
Unlike liquid phase bilayers, the lipids in a gel phase bilayer have less mobility. The phase behavior of lipid bilayers is ... Among the most common model systems are: Black lipid membranes (BLM) Supported lipid bilayers (SLB) Tethered Bilayer Lipid ... The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes are ... Another potential application of lipid bilayers is the field of biosensors. Since the lipid bilayer is the barrier between the ...
A characteristic of nearly all organisms is their ability to accomodate the fatty acid composition of their lipids to growth ... Melchior D.L., Steim J.M. (1978) The Self Control of Lipid Bilayers. In: Johnson J.F., Porter R.S. (eds) Liquid Crystals and ... in lipids synthesized at lower growth temperatures. The obvious physical result of this adjustment is a depression of lipid ... A characteristic of nearly all organisms is their ability to accomodate the fatty acid composition of their lipids to growth ...
... the bilayers are said to be hemifused. In hemifusion, the lipid constituents of the outer leaflet of the two bilayers can mix, ... In membrane biology, fusion is the process by which two initially distinct lipid bilayers merge their hydrophobic cores, ... enveloped viruses are those surrounded by a lipid bilayer; some others have only a protein coat). Broadly, there are two ... particularly in eukaryotes since the eukaryotic cell is extensively sub-divided by lipid bilayer membranes. Exocytosis, ...
Plasmid-lipid particles which are useful for transfection of cells in vitro or in vivo are described. The particles can be ... This example illustrates the level of plasmid encapsulated in lipid bilayers. Empty lipid complexes containing an aqueous space ... Reverse head group lipids, lipid particle compositions comprising reverse headgroup lipids, and methods for the delivery of ... b) contacting non-cationic lipids with the coated plasmid-lipid complex to form a detergent solution comprising a plasmid-lipid ...
Purchase Advances in Planar Lipid Bilayers and Liposomes, Volume 5 - 1st Edition. Print Book & E-Book. ISBN 9780123736871, ... Pure Lipid Pores in Unmodified Planar Bilayer Lipid Membrane at the Phase Transition from the Liquid Crystalline State to the ... Advances in Planar Lipid Bilayers and Liposomes, Volume 5 1st Edition. 0.0 star rating Write a review ... Piercing Lipid Bilayers with Peptides (E.E. Ambroggio et al.). *Liposomes as a Tool for the Study of the Chronic Actions of ...
Purchase Advances in Planar Lipid Bilayers and Liposomes, Volume 12 - 1st Edition. Print Book & E-Book. ISBN 9780123812667, ... Advances in Planar Lipid Bilayers and Liposomes, Volume 12 1st Edition. 0 star rating Write a review ... Advances in Planar Lipid Bilayers and Liposomes, Volume 9, continues to include invited chapters on a broad range of topics, ... 5. Micropatterned lipid bilayer membranes on solid sub strates, Morigaki. 6. Salt-induced morphological transitions in non- ...
Small angle neutron diffraction from flat lipid bilayers that are hydrated through water vapor has been employed to eliminate ... has shifted in the way that alcohol loaded bilayers absorbed more water molecules when compared to the neat lipid bilayers. The ... We investigate the structural changes to lipid membrane that ensue from the addition of aliphatic alcohols with various alkyl ... bilayer thickness; area per lipid; order parameter; lateral pressure general anesthetics; alcohols; lipid bilayers; small-angle ...
With various lipids, originating from biological sources, such as egg yolk phosphatidylcholine, soybean phosphatidylcholine or ... Planar bilayer membranes were made from commercially available lipids. ... Planar bilayer membranes were made from commercially available lipids. With various lipids, originating from biological sources ... Planar lipid membranes commercially lipids monolayer self-assembly channels This is a preview of subscription content, log in ...
Proteins are kept within the lipid bilayer of a cell by a number of different means depending on their type. Integral proteins ... Lipid-bound proteins are held entirely within the lipid bilayer by a glycosylphosphatidylinositol anchor. ... Proteins are kept within the lipid bilayer of a cell by a number of different means depending on their type. Integral proteins ... What Keeps Proteins Within the Lipid Bilayer? By Staff WriterLast Updated Mar 24, 2020 5:20:12 PM ET ...
Tags: membrane biophysicsstructuremembrane structurefluid phase bilayerslipid bilayercomplete structure ... How the "Tumultuous Chemical Heterogeneity" of the Lipid Bilayer Membrane Was Finally Revealed in the Biophysical Journal. ... How the "Tumultuous Chemical Heterogeneity" of the Lipid Bilayer Membrane Was Finally Revealed in the Biophysical Journal ...
... and to study lipid membranes on curved and closed geometries. These novel applications of CSLBs rely on previously unapprecia ... The use of colloid supported lipid bilayers (CSLBs) has recently been extended to create colloidal joints, that enable the ... Colloid supported lipid bilayers for self-assembly M. Rinaldin, R. W. Verweij, I. Chakraborty and D. J. Kraft, Soft Matter, ... The use of colloid supported lipid bilayers (CSLBs) has recently been extended to create colloidal joints, that enable the ...
Stochastic transport through carbon nanotubes in lipid bilayers and live cell membranes.. Geng J1, Kim K2, Zhang J3, Escalada A ... Here we show that short CNTs spontaneously insert into lipid bilayers and live cell membranes to form channels that exhibit a ... Moreover, simulations predict that CNTs with a length comparable to the thickness of a lipid bilayer membrane can self-insert ... Functionalized CNTs have indeed been found to penetrate lipid membranes and cell walls, and short tubes have been forced into ...
Lipid bilayer and cytoskeletal interactions. Zhangli Peng, Xuejin Li, Igor V. Pivkin, Ming Dao, George E. Karniadakis, Subra ... Lipid bilayer and cytoskeletal interactions. Zhangli Peng, Xuejin Li, Igor V. Pivkin, Ming Dao, George E. Karniadakis, Subra ... Lipid bilayer and cytoskeletal interactions in a red blood cell. Zhangli Peng, Xuejin Li, Igor V. Pivkin, Ming Dao, George E. ... We treated the lipid bilayer and the cytoskeleton as two distinct components and developed a unique whole-cell model of the RBC ...
The lipid bilayers present in cell membranes are selectively permeable. It allows the diffusion of some substances such as ... Water diffusion occurs due to differences in solute concentration across the lipid bilayer. However, ions do not easily diffuse ... b. lipid is to fat. c. collagen is to protein. d..... Biology: The Dynamic Science (MindTap Course List) ...
Advances in Planar Lipid Bilayers and Liposomes by Ales Iglic, 9780123810144, available at Book Depository with free delivery ... Advances in Planar Lipid Bilayers and Liposomes, Volume 11 includes invited chapters on a broad range of topics, covering both ... Explores the planar lipid bilayer systems and spherical liposomes from both theoretical and experimental perspectives. * Serves ... This volume addresses the broader goal with both systems, planar lipid bilayers and spherical liposomes, which is the further ...
... lipid bilayers and model membranes : from basic research to application. [Georg Pabst; Norbert Kučerka; Mu-Ping Nieh; J ... this book provides a comprehensive collection of state-of-the-art lipid/model membrane research and industrial/technological ... Liposomes, lipid bilayers and model membranes : from basic research to application. Author:. Georg Pabst; Norbert Kučerka; Mu- ... Liposomes, lipid bilayers and model membranes : from basic research to application/Georg Pabst; Norbert Kučerka; Mu-Ping Nieh ...
Lipid bilayers are important in biological cells. They are the basis of cell membranes, and they surround most cell organelles ... Lipid bilayers form automatically from phospholipids by self-assembly. The phospholipids have heads which mix with water and ... The lipid bilayers stop most water-soluble (hydrophilic) molecules passing through. They also stop most ions. ... In cells, proteins are put in the bilayer by enzymes. The proteins decide which molecules come in and which go out of the cell ...
291b) Simulation Study of the Impact of Cholesterol on Ceramide-Based Lipid Bilayers. *Conference: AIChE Annual Meeting ... Simulations Study of the Structure and Phase Behavior of Ceramide Bilayers and the Role of Lipid Headgroup Chemistry, J. Chem. ... mixtures of ceramides and cholesterol in a bilayer configuration are examined and compared to pure ceramide bilayers. Due to ... The lipids control the barrier function of the skin, however, the molecular level organization of the species and their role in ...
... because cholesterol and the oxidized lipid have complementary shapes and (2 Interaction of nano-objects with lipid membranes ... cholesterol protects bilayers from disruption caused by lipid oxidation by sequestering conical shaped oxidized lipid species ... Pairing of cholesterol with oxidized phospholipid species in lipid bilayers Himanshu Khandelia,*a Bastien Loubet,a Agnieszka ... cholesterol protects bilayers from disruption caused by lipid oxidation by sequestering conical shaped oxidized lipid species ...
hIAPP monomer inserts into POPC lipid bilayers more readily than into POPG bilayers. Peptide-lipid interaction analyses show ... we calculate the thickness of lipid bilayer and the order parameter of the lipid acyl chain (sn-1). The thickness of lipid ... showing that the peptide inserts more deeply in zwitterionic lipid bilayers than that in anionic lipid bilayers [96]. ... Binding Orientations and Lipid Interactions of Human Amylin at Zwitterionic and Anionic Lipid Bilayers. Zhenyu Qian, Yan Jia, ...
The perturbation of model lipid bilayer vesicles by halogenated hydrocarbons was investigated to determine if cellular membrane ... The perturbation of model lipid bilayer vesicles by halogenated hydrocarbons was investigated to determine if cellular membrane ... Toxicity of Halogenated Compounds on Lipid Bilayers: Report on Project VKC-C23-169.. ...
... especially the lipid bilayer environment. Tethered lipid bilayers represent one of the most promising classes of model ... Taken together, the capabilities of tethered lipid bilayers have opened the door to biotechnology applications in healthcare, ... future opportunities for tethered lipid bilayers within the biotechnology field are discussed. ... membranes and are based on the immobilization of a planar lipid bilayer on a solid support that enables characterization by a ...
Bilayers on thicker, more tortuous, and hydrophobic materials produced higher current levels. Bilayers that self-assembled on ... and thickness were examined for their ability to support bilayer lipid membranes as determined by electrical impedance ... Bilayers supported by hydrophobic materials (PTFE, polycarbonate, nylon, and silanised silver) had optimal resistance (14-19 GΩ ... using a method recently reported to improve the efficiency of proteoliposome incorporation into PTFE-supported bilayers. ...
Chemistry and physics of lipids 2015-5-11 Effect of n-alkanes on lipid bilayers depending on headgroups.. [Mafumi Hishida, ... The results of X-ray diffraction show that the enthalpic stabilization due to enhanced packing of acyl chains of the lipid by ... Change in the temperatures of main transition of the lipid/alkane mixtures against the length of added alkanes depends largely ... Phase behavior and structural properties were examined for phospholipid bilayers having different headgroups (DMPC, DMPS and ...
Production of Dynamic Lipid Bilayers .... Production of Dynamic Lipid Bilayers Using the Reversible Thiol-Thioester Exchange ...
  • This bilayer is the basis of the membranes of living cells. (britannica.com)
  • To study aspects of cellular membranes in a con trolled manner, solid supported planar bilayers have served as reliable tools for many decades. (scirp.org)
  • The cell membranes of almost all organisms and many viruses are made of a lipid bilayer, as are the nuclear membrane surrounding the cell nucleus, and membranes of the membrane-bound organelles in the cell. (wikipedia.org)
  • Bilayers are particularly impermeable to ions, which allows cells to regulate salt concentrations and pH by transporting ions across their membranes using proteins called ion pumps. (wikipedia.org)
  • Phospholipids with certain head groups can alter the surface chemistry of a bilayer and can, for example, serve as signals as well as "anchors" for other molecules in the membranes of cells. (wikipedia.org)
  • 13.Transmembrane Polarity Profile of Lipid Membranes (Vesna Noethig-Laslo, M. Sentjurc). (elsevier.com)
  • Fusion is involved in many cellular processes, particularly in eukaryotes since the eukaryotic cell is extensively sub-divided by lipid bilayer membranes. (wikipedia.org)
  • One role on these ions in the fusion process is to shield the negative charge on the surface of the bilayer, diminishing electrostatic repulsion and allowing the membranes to approach each other. (wikipedia.org)
  • Planar bilayer membranes were made from commercially available lipids. (springer.com)
  • Montal M, Mueller P (1972) Formation of bimolecular membranes from lipid monolayers and a study of their electrical properties. (springer.com)
  • The use of colloid supported lipid bilayers (CSLBs) has recently been extended to create colloidal joints, that enable the assembly of structures with internal degrees of flexibility, and to study lipid membranes on curved and closed geometries. (rsc.org)
  • Stochastic transport through carbon nanotubes in lipid bilayers and live cell membranes. (nih.gov)
  • Functionalized CNTs have indeed been found to penetrate lipid membranes and cell walls, and short tubes have been forced into membranes to create sensors, yet membrane transport applications of short CNTs remain underexplored. (nih.gov)
  • The lipid bilayers present in cell membranes are selectively permeable. (bartleby.com)
  • Liposomes, lipid bilayers and model membranes. (worldcat.org)
  • In the presence of lipid membranes, hIAPP initially binds to the membrane in a helical state [ 21 , 26 ]. (hindawi.com)
  • The importance of cell membranes in biological systems has prompted the development of model membrane platforms that recapitulate fundamental aspects of membrane biology, especially the lipid bilayer environment. (mdpi.com)
  • Tethered lipid bilayers represent one of the most promising classes of model membranes and are based on the immobilization of a planar lipid bilayer on a solid support that enables characterization by a wide range of surface-sensitive analytical techniques. (mdpi.com)
  • Moreover, as the result of molecular engineering inspired by biology, tethered bilayers are increasingly able to mimic fundamental properties of natural cell membranes, including fluidity, electrical sealing and hosting transmembrane proteins. (mdpi.com)
  • To identify materials suitable as membrane supports for ion channel biosensors, six filter materials of varying hydrophobicity, tortuosity, and thickness were examined for their ability to support bilayer lipid membranes as determined by electrical impedance spectroscopy. (hindawi.com)
  • Additionally, there is evidence for pattern formation in cell membranes due to the presence of various lipids. (aps.org)
  • Here, we use MD to study the interactions between alcohols and pure lipid bilayers as well as pattern formation in mixed membranes using atomistic and coarse-grained models. (aps.org)
  • Previous direct measurements of demixed lipid membranes have always found a liquid-ordered phase that is thicker than the liquid-disordered phase. (sigmaaldrich.com)
  • We found no monotonic relationship between demixing temperatures of these ternary systems and either estimated thickness mismatches between the liquid phases or the physical parameters of single-component membranes composed of the individual lipids. (sigmaaldrich.com)
  • The bridging effect of Ca 2+ between the negatively charged E. coli lipid bilayers and substrate is the dominant factor determining the two-dimensional and three-dimensional morphology of the E. coli lipid bilayer membranes. (frontiersin.org)
  • In this study, we investigated microscopic two-dimensional and three-dimensional organization of lipid membranes comprising of PLE and their dependence on Ca 2+ concentration ([Ca 2+ ]) with fluorescence microscopy and AFM. (frontiersin.org)
  • We have used neutron diffraction, solid-state nuclear magnetic resonance spectroscopy, and molecular dynamics simulations to investigate the structure and hydration of bilayer membranes containing S1-S4 voltage-sensing domains. (aps.org)
  • Polymyxin interaction with negatively charged lipid bilayer membranes and the competitive effect of Ca2+. (nih.gov)
  • From the theoretical aspect, mechanical properties of lipid membranes are commonly investigated based on the Helfrich Hamiltonian. (frontiersin.org)
  • T his page describes the structure fluid lipid bilayer membranes determined by means of X-ray and neutron diffraction methods developed in our laboratory. (uci.edu)
  • Because cellular membranes must be in a fluid state for normal cell function, it is the structure of fluid (Lα-phase) bilayers that is relevant to understanding the interactions of peptides in molecular detail. (uci.edu)
  • A. Agrawal, D.J. Steigmann, Boundary-value problems in the theory of lipid membranes. (springer.com)
  • In an effort to develop a general thermodynamic model from first-principles to describe the mixing behavior of lipid membranes, we examined lipid mixing induced by targeted binding of small (Green Fluorescent Protein (GFP)) and large (nanolipoprotein particles (NLPs)) structures to specific phases of phase-separated lipid bilayers. (osti.gov)
  • Progress with respect to enrichment and separation of native membrane components in complex lipid environments, such as native cell membranes, has so far been very limited. (chalmers.se)
  • The reason for the slow progress can be related to the lack of efficient means to generate continuous and laterally fluid supported lipid bilayers (SLBs) made from real cell membranes. (chalmers.se)
  • We show in this work how the edge of a hydrodynamically driven SLB can be used to induce rupture of adsorbed lipid vesicles of compositions that typically prevent spontaneous SLB formation, such as vesicles made of complex lipid compositions, containing high cholesterol content or being derived from real cell membranes. (chalmers.se)
  • To learn more on the lipid-lipid interactions governing this lateral heterogeneity, different techniques have been utilized to study lipid interactions in both simple and more complex model membranes. (doria.fi)
  • We prove that lipid membranes of genus zero (homeomorphic to a sphere) can be modelled either as locally or globally area preserving by showing that the two formulations are equivalent with respect to determining equilibrium solutions and their stability. (cornell.edu)
  • Bilayer lipid membranes are created in a polymeric device by contacting monolayers formed at a two-phase liquid-liquid interface. (soton.ac.uk)
  • Absolutely essential for all life on Earth, lipid bilayers are a critical component of all biological membranes, including cell membranes. (thefreedictionary.com)
  • This allows for the measurement of the free energy of ClC-ec1 dimerization in lipid bilayers, revealing that it is one of the strongest membrane protein complexes measured so far, and introduces it as new type of dimerization model to investigate the physical forces that drive membrane protein association in membranes. (elifesciences.org)
  • These membranes primarily consist of fatty molecules called lipids, but they are also packed with proteins such as ion channels and transporters that control which molecules pass in and out of the cell. (elifesciences.org)
  • In this work, coarse-grained molecular simulations were used to investigate the influence of small alkanethiolate-coated gold nanoparticles on the properties of lipid bilayers as a model for cell membranes. (tu-darmstadt.de)
  • Simulations of the bilayers in the absence of nanoparticles were used for model validation and as a reference for unperturbed membranes. (tu-darmstadt.de)
  • Small systems with 10 × 10 nm bilayer patches with all six possible combinations of the two nanoparticles and three lipid bilayers were used to investigate nanoparticle attachment to the membranes. (tu-darmstadt.de)
  • PC+ PE etc) and species to intact natural membranes (i.e. including proteins and bilayer organizational factors). (spie.org)
  • NABBs containing KcsA were stable, homogeneous, and able to spontaneously deliver the channel to black lipid membranes without measurably affecting the electrical properties of the bilayer. (rupress.org)
  • and monitored electrophysiologically using black lipid membranes (BLMs). (rupress.org)
  • Diffusion of carbon dioxide through lipid bilayer membranes: effects of carbonic anhydrase, bicarbonate, and unstirred layers. (harvard.edu)
  • Primary source abstract:'Diffusion of (14)C-labeled CO(2) was measured through lipid bilayer membranes composed of egg lecithin and cholesterol (1:1 mol ratio) dissolved in n-decane. (harvard.edu)
  • However, it would take decades before lipid bilayers were identified as the essential constituent of membranes. (rupress.org)
  • In this paper, I first discuss how our understanding of cell membranes went from invisible boundaries to fluid lipid bilayers. (rupress.org)
  • One of the key lockers to understand mechanisms of biological action of drugs and natural compounds is their capacity to incorporate/cross lipid bilayer membranes. (archives-ouvertes.fr)
  • Using MD simulations, we have explored the capacity of several compounds (polyphenols, vitamins E and C, plantazolicin, carprofens) to incorporate lipid bilayer membranes. (archives-ouvertes.fr)
  • In order to rationalize their mechanisms of action, their position and orientation in membranes as well as their capacity to accumulate or permeate lipid bilayers were assessed. (archives-ouvertes.fr)
  • Leurs positions et orientations ainsi que leur capacité à s'accumuler ou à traverser les membranes ont été évaluées pour comprendre leurs mécanismes d'action.Dans le but d'utiliser les simulations de dynamique moléculaire en drug design, l'accent a été mis sur la précision des calculs, qui dépend de la qualité sous-jacente du modèle utilisé. (archives-ouvertes.fr)
  • Le choix du champ de force, les paramètres des composés étudiés ainsi que la composition de la membrane sont en particulier apparus comme d'importants facteurs dans la description des interactions entre les molécules naturelles et thérapeutiques et les membranes. (archives-ouvertes.fr)
  • Cellular membranes are inhomogeneous in nature and are composed of various kinds of lipids and proteins in interaction with their environments. (taylorfrancis.com)
  • Ion interactions with biological membranes not only affect structure, dynamics, and stability of bilayers, but also affect protein binding, folding, aggregation, and insertion in a lipid bilayer environment. (taylorfrancis.com)
  • It suggests that cations of particular sizes have the ability to induce nanodomains in lipid bilayers, which can significantly affect structural and organizational properties of the bilayer and hence regulate function of cellular membranes. (taylorfrancis.com)
  • Simple binary or ternary lipid systems are well established, whereas more complex model membranes containing biologically important signaling lipids such as phosphatidylinositol-4,5-bisphosphate (PI-(4,5)-P 2 ) and cholesterol have not been extensively described yet. (figshare.com)
  • Aliskiren's thermal effects on the pre- and main transition of dipalmitoyl-phosphatidylcholine (DPPC) membranes as well as its topographical position in the bilayer show striking similarities to those of angiotensin II type 1 receptor (AT1R) antagonists. (whiterose.ac.uk)
  • Laub KR, Witschas K, Blicher A, Madsen SB, Lückhoff A, Heimburg T. Comparing ion conductance recordings of synthetic lipid bilayers with cell membranes containing TRP channels. (ugent.be)
  • Vesicles made by model bilayers have also been used clinically to deliver drugs. (wikipedia.org)
  • Lipid Vesicles - Development and Applications for Studding Membrane Heterogeneity and Interactions (N. Puff, M.I. Angelova). (elsevier.com)
  • 10.SNARE-induced Fusion of Vesicles to a Planar Bilayer (D.J. Woodbury et al . (elsevier.com)
  • To simplify the system and allow more definitive study, many experiments have been performed in vitro with synthetic lipid vesicles. (wikipedia.org)
  • Schindler H (1980) Formation of planar bilayers from artificial or native membrane vesicles. (springer.com)
  • The protective effect of cholesterol on oxidized lipids has been observed previously using electron paramagnetic resonance (EPR) and electron microscopy imaging of vesicles. (rsc.org)
  • Electron paramagnetic resonance (EPR) spectroscopy study showed that the α -helical region of hIAPP at neutral pH spans residues 9~22 and is oriented parallel to the surface of large unilamellar vesicles containing negatively charged lipids [ 27 ]. (hindawi.com)
  • The perturbation of model lipid bilayer vesicles by halogenated hydrocarbons was investigated to determine if cellular membrane damage could be evaluated and used as a screening technique for toxicity. (cdc.gov)
  • In giant unilamellar vesicles (GUVs), GFP and NLPs bound to the Lo domains of bilayers containing DPIDA, and bound to the Ld region of bilayers containing DOIDA. (osti.gov)
  • In this work, we use the popular Helfrich-Cahn-Hilliard phase field model for two-component lipid bilayer vesicles to systematically study phase transitions in lipid vesicles. (cornell.edu)
  • Asymmetric pore distribution and loss of membrane lipid in electroporated DOPC vesicles. (semanticscholar.org)
  • Super Resolution Microscopy of Lipid Bilayer Phases and Single Molecule Kinetic Studies on Merocyanine 540 Bound Lipid Vesicles. (upenn.edu)
  • Kuo, Chin-Kuei, "Super Resolution Microscopy of Lipid Bilayer Phases and Single Molecule Kinetic Studies on Merocyanine 540 Bound Lipid Vesicles. (upenn.edu)
  • Volume 5 presents recent research on both planar lipid bilayers and liposomes based on their historic and experimental realization. (elsevier.com)
  • Advances in Planar Lipid Bilayers and Liposomes, Volume 5, continues to include invited chapters on a broad range of topics, covering both main arrangements of the reconstituted system, namely planar lipid bilayers and spherical liposomes. (elsevier.com)
  • This volume keeps in mind the broader goal with both systems, planar lipid bilayers and spherical liposomes, which is the further development of this interdisciplinary field worldwide. (elsevier.com)
  • Advances in Planar Lipid Bilayers and Liposomes, Volume 11 includes invited chapters on a broad range of topics, covering both of the main arrangements of the reconstituted system, namely planar lipid bilayers and spherical liposomes. (bookdepository.com)
  • This volume addresses the broader goal with both systems, planar lipid bilayers and spherical liposomes, which is the further development of this interdisciplinary field worldwide. (bookdepository.com)
  • Advances in Planar Lipid Bilayers and Liposomes volumes cover a broad range of topics, including main arrangements of the reconstituted system, namely planar lipid bilayers as well as spherical liposomes. (researchandmarkets.com)
  • Advances in Planar Lipid Bilayers and Liposomes Edition by A. Leitmannova Liu and Publisher Academic Press. (vitalsource.com)
  • Tethered Fibronectin Liposomes on Supported Lipid Bilayers as a Pre-Packaged Controlled-Release Platform for Cell-Based Assays. (biomedsearch.com)
  • A biomimetic construct containing an extracellular matrix protein-liposome composite tethered on supported lipid bilayers (SLBs) was formed with fibronectin (FN), and polyethylene glycol (PEG) and cholesterol-containing liposomes. (biomedsearch.com)
  • Importantly, diffusion coefficients for lipids over these cavities are 2 to 3 times faster than on flat PDMS, and are more akin to diffusion rates normally observed in liposomes, indicating that the bilayer is minimally influenced by the underlying substrate. (dcu.ie)
  • We have investigated the effects of several heavy metal cations on the proton and chloride permeabilities of liposomes prepared with endogenous lipids from brain myelin, by monitoring the fluorescence emitted by acridine orange and N-(6-methoxyquinolyl)acetoethyl ester. (aspetjournals.org)
  • In conclusion, by formulating the organogel into the lipid bilayers, gel-liposomes were developed, allowing for sustained drug release, improved internalization and the resultant enhancement of cytotoxicity of chemotherapy agent to cancer cells. (ovid.com)
  • However, it is not known whether MPs incorporated in these lipid nanoparticles retain the range of key functional properties, as established with other lipid preparations like liposomes and planar lipid bilayers, which are generally used for single-molecule measurements of the movement of ions and molecules through ion channels and transporters. (rupress.org)
  • Traditional biophysical assays of purified ion channels in lipid bilayers are performed via reconstitution of detergent-solubilized channels into liposomes, followed by fusion of these channel-containing proteoliposomes with the target bilayer. (rupress.org)
  • Adv. Planar Lipid Bilayers Liposomes (2014): 137-153. (utexas.edu)
  • We study the biomechanical interactions between the lipid bilayer and the cytoskeleton in a red blood cell (RBC) by developing a general framework for mesoscopic simulations. (pnas.org)
  • Finally, we simulated the bilayer-cytoskeletal detachment in channel flow to quantify the strength of such interactions when the corresponding bonds break. (pnas.org)
  • Taken together, these experiments and corresponding systematic DPD simulations probe the governing constitutive response of the cytoskeleton, elastic stiffness, viscous friction, and strength of bilayer-cytoskeletal interactions as well as membrane viscosities. (pnas.org)
  • Hence, the DPD simulations and comparisons with available independent experiments serve as validation of the unique two-component model and lead to useful insights into the biomechanical interactions between the lipid bilayer and the cytoskeleton of the RBC. (pnas.org)
  • However, the detailed hIAPP-membrane interactions and the influences of lipid compositions are unclear. (hindawi.com)
  • Peptide-lipid interaction analyses show that the different binding features of hIAPP at POPC and POPG bilayers are attributed to different magnitudes of electrostatic and hydrogen-bonding interactions with lipids. (hindawi.com)
  • We also examine the effects of lipid-alcohol interactions on membrane curvature with the CG model and find satisfactory system representation. (aps.org)
  • This problem is particularly relevant in the case of the highly-charged S1-S4 voltage- sensing domains responsible for nerve impulses, where interactions with the lipid bilayer are critical for the function of voltage-activated potassium channels. (aps.org)
  • It is also shown how static and kinetic information about the intermolecular interactions in the lipid bilayer can be obtained by relating how the magnitude of the. (lu.se)
  • It is also shown how static and kinetic information about the intermolecular interactions in the lipid bilayer can be obtained by relating how the magnitude of the hydrodynamic forces affects the accumulation of protein molecules in the trap. (lu.se)
  • Our combined electrophysiology and fluorescence microscopy approach is experimentally straightforward and enables rapid systematic investigation of the interactions between nanoparticles and the lipid components of the cell membrane. (soton.ac.uk)
  • Understanding interactions between functionalized gold nanoparticles (NPs) and lipid bilayers is essential for their use in biomedical applications. (aiche.org)
  • Experiments and continuum-scale simulations have suggested that small (~5 nm diameter) cationic NPs aggregate when adsorbed to the surface of zwitterionic lipid bilayers despite being stable in aqueous solution, suggesting that bilayer-mediated interactions facilitate assembly. (aiche.org)
  • In this work, we use chemically specific coarse-grained molecular dynamics simulations to show that cationic NP adsorption to lipid bilayers is driven by a balance between favorable NP-lipid interactions and the unfavorable mechanical deformation of the bilayer to create local curvature. (aiche.org)
  • We measure the bilayer-mediated interactions between two adsorbed NPs by comparing the aggregation free energy on a bilayer to that in solution. (aiche.org)
  • These simulation results indicate that bilayer curvature mediates interactions between adsorbed NPs and favors alignment near phase boundaries. (aiche.org)
  • Lipid interactions with membrane proteins are a crucial but often overlooked effector of cell physiology. (cornell.edu)
  • In addition, there is increasing evidence that the cell membrane is heterogeneous with dynamic "raft" domains with different compositions and the dynamics of these domains could regulate membrane protein function via lipid-protein interactions. (cornell.edu)
  • When studying membrane proteins in cells, these types of lipid-protein interactions are preserved, but decoupling to elucidate specific mechanisms is difficult because of the complexity of the cell system. (cornell.edu)
  • Other techniques use detergent solubilized membrane proteins to reduce complexity, but lipid interactions are also lost. (cornell.edu)
  • This thermal motion is a fundamental and important feature of fluid bilayers that plays a critical role in peptide-bilayer interactions. (uci.edu)
  • Our data demonstrate conclusively that TRPM8 is gated by cold and its chemical agonists directly, and that dependence of its gating on PI(4,5)P 2 is a result of direct specific interactions with the lipid. (jneurosci.org)
  • Small structural nuances in the lipids can lead to very different lipid interactions. (doria.fi)
  • In paper II, deuterated PLs and fluorescent lipid-analog probes were utilized to understand cholesterol interactions in complex bilayers containing N-palmitoylsphingomyelin (PSM) and glycerophospholipids (GPLs) with different head groups. (doria.fi)
  • Cholesterol seemed to have more favorable interactions with PSM even in the presence of the other GPLs, while it did not favor any particular GPLs over the others, at least at the lipid compositions examined. (doria.fi)
  • Interactions between membrane protein interfaces in lipid bilayers play an important role in membrane protein folding but quantification of the strength of these interactions has been challenging. (elifesciences.org)
  • They showed that electrostatic interactions are guiding the nanoparticle attachment on the lipid bilayers and that there is a weaker and a stronger state of attachment. (tu-darmstadt.de)
  • This can impede lipid fluidity and is particularly detrimental to mobility of reconstituted proteins as substrate-protein interactions can impede motion and even cause protein to denature. (dcu.ie)
  • In particular, force field selection, xenobiotic parameterization and bilayer constitution emerged as crucial factors to appropriately depict drug-membrane interactions. (archives-ouvertes.fr)
  • Les simulations de dynamique moléculaire ont ouvert de nombreuses perspectives ces dernières années en offrant la possibilité de décrire ces interactions intermoléculaires au niveau atomique. (archives-ouvertes.fr)
  • The chapter presents a generic Water-Explicit Polarizable MEMbrane (WEPMEM) lipid model for anionic and zwitterionic lipids with the inclusion of dipolar interactions in the lipid headgroup region. (taylorfrancis.com)
  • Given that the calculated fast reorientational correlation times and the "microscopic" lateral diffusion of the lipids show excellent agreement with the experimental results, it is concluded that the apparently high viscosity of the membrane is more closely related to molecular interactions on the surface rather than in the interior. (sciencemag.org)
  • Solid-supported lipid bilayers (SLBs) mimicking a biological membrane are commonly used to investigate lipid-lipid or lipid-protein interactions. (figshare.com)
  • Moreover, simulations predict that CNTs with a length comparable to the thickness of a lipid bilayer membrane can self-insert into the membrane. (nih.gov)
  • The evidence for bilayer protection comes from molecular dynamics (MD) simulations and dynamic light scattering (DLS) measurements. (rsc.org)
  • In simulations, bilayers containing high amounts of PZPC become porous, unless cholesterol is also present. (rsc.org)
  • The evidence for the pairing of cholesterol and PZPC comes mainly from correlated 2-D density and thickness plots from simulations, which show that these two molecules co-localize in bilayers. (rsc.org)
  • Further evidence that the two molecules can cohabitate comes from self-assembly simulations, where we show that cholesterol-oxidized lipid mixtures can form lamellar phases at specific concentrations, reminiscent of lysolipid-cholesterol mixtures. (rsc.org)
  • In this study, as a first step to understand the mechanism of membrane-mediated hIAPP aggregation, we investigate the binding behaviors of hIAPP monomer at zwitterionic palmitoyloleoyl-phosphatidylcholine (POPC) bilayer by performing atomistic molecular dynamics simulations. (hindawi.com)
  • Molecular simulations of different holo and apoenzyme complexes of SSTR2 in the presence and absence of a lipid bilayer were performed, observed, and correlated with previously reported studies. (nature.com)
  • These simulations indicate that the bilayer contributes an attractive interaction between the nanoparticles associated with the reduction in induced curvature. (aiche.org)
  • In this work, we introduce a method for determining the Poisson's ratio ν in simulations and apply it to the coarse grained lipid membrane model, which was introduced by Lenz and Schmid (2005) . (frontiersin.org)
  • Monte Carlo simulations of lipid bilayers with periodic boundary conditions in lateral directions were carried out for the coarse grained model introduced by Lenz and Schmid (2005) . (frontiersin.org)
  • A careful analysis of time-resolved resonance energy transfer experiments by means of analytical models as well as Monte Carlo simulations shows that the mPE derivatives have a comparable affinity to highly curved bilayer regions (torroidal pores formed by magainin-2 in lipid bilayers, or the rims of discoid bicelles) and to planar bilayer regions (i.e. the flat region of lipid bilayers and bicelles). (diva-portal.org)
  • Here, a combination of FRET and Monte Carlo simulations enables the localisation of probes in bicelles and in bilayers containing pores, i.e. in lipid systems with variable curvature, or in non-homogenous lipid systems. (diva-portal.org)
  • Using complementary approaches of planar lipid bilayer (PLB) electrophysiological recordings and molecular dynamics (MD) simulations, we show that the d -Aβ isomer exhibits ion conductance behavior in the bilayer indistinguishable from that described earlier for the l -Aβ isomer. (pubmedcentralcanada.ca)
  • In the simulations three different lipid bilayers in water consisting of pure 1-palmitoyl-2-oleoyl-sn-glycero-3- phosphocholin (POPC), pure 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) sodium salt (POPG) and a mixture of the two in molar ratio 1:1 were used. (tu-darmstadt.de)
  • All simulations featured a lipid bilayer in water in the middle of the simulation box with one or more nanoparticles placed in the water above the bilayer. (tu-darmstadt.de)
  • Bigger simulations with 40×40 nm membrane patches and four or 16 nanoparticles were used to investigate the influence of the nanoparticles on the structural properties of the bilayers. (tu-darmstadt.de)
  • Molecular dynamics simulations of hydrophilic pores in lipid bilayers. (semanticscholar.org)
  • article{Leontiadou2004MolecularDS, title={Molecular dynamics simulations of hydrophilic pores in lipid bilayers. (semanticscholar.org)
  • To study the properties of these structures and understand the mechanism by which pore expansion leads to membrane rupture, a series of molecular dynamics simulations of a dipalmitoylphosphatidylcholine (DPPC) bilayer have been conducted. (semanticscholar.org)
  • Molecular dynamics simulations of pore formation dynamics during the rupture process of a phospholipid bilayer caused by high-speed equibiaxial stretching. (semanticscholar.org)
  • Molecular dynamics simulations of a fluid-phase dipalmitoyl phosphatidylcholine lipid bilayer in water and of neat hexadecane are reported and compared with nuclear magnetic resonance spin-lattice relaxation and quasi-elastic neutron scattering data. (sciencemag.org)
  • Further evidence cited in favor of this theory is the fact that certain lipid mixtures have been shown to only support fusion when raised above the transition temperature of these inverted phases. (wikipedia.org)
  • To understand the role of cholesterol, mixtures of ceramides and cholesterol in a bilayer configuration are examined and compared to pure ceramide bilayers. (aiche.org)
  • We claim that (1) cholesterol protects bilayers from disruption caused by lipid oxidation by sequestering conical shaped oxidized lipid species such as 1-palmitoyl-2-azelaoyl- sn-glycero -3-phosphocholine (PZPC) away from phospholipid, because cholesterol and the oxidized lipid have complementary shapes and (2) mixtures of cholesterol and oxidized lipids can self-assemble into bilayers much like lysolipid-cholesterol mixtures. (rsc.org)
  • Oxidized lipids are ubiquitously present in significant amounts in high- and low-density lipoprotein (HDL and LDL) particles, diseased tissues, and in model phospholipid mixtures containing polyunsaturated lipids. (rsc.org)
  • diseases related to oxidized lipids, and to biophysical studies of phase behaviour of cholesterol-containing phospholipid mixtures. (rsc.org)
  • Change in the temperatures of main transition of the lipid/alkane mixtures against the length of added alkanes depends largely on the headgroup. (sigmaaldrich.com)
  • Here we investigated noncanonical ternary lipid mixtures designed to produce bilayers with thicker disordered phases than ordered phases. (sigmaaldrich.com)
  • Here, we direct the self-assembly of RNA building blocks into three-dimensional structures of RNA on fluid lipid bilayers composed of cationic 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or mixtures of zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) and cationic sphingosine. (chalmers.se)
  • By studying single, binary, ternary etc mixtures and varying the composition of the monolayers the role of each lipid class was studied in detail. (lu.se)
  • The lipids were identified in the complex mixtures from the shape, size and difference in thickness of the different domains. (lu.se)
  • Phases were targeted by incorporation of phase-partitioning iminodiacetic acid (IDA)-functionalized lipids into ternary lipid mixtures consisting of DPPC, DOPC, and cholesterol. (osti.gov)
  • For the latter issue, lipid mixtures e.g., including cholesterol have been developed. (archives-ouvertes.fr)
  • Coarse-grained (CG) models, which allows us to explore longer time scales and larger systems, have yielded significant results in the understanding of lipid-lipid interaction or tail-induced phase separation in lipid mixtures. (taylorfrancis.com)
  • We show that these mixtures form homogeneous solid-supported bilayers that exhibit no intrinsic phase separation and are characterized by long-term stability (>8 h). (figshare.com)
  • These observations are compared to the phase behavior of lipid mixtures, which we determined by X-ray scattering and differential scanning calorimetry or extracted from the existing literature. (utexas.edu)
  • Lipid molecules of this composition spontaneously form aggregate structures such as micelles and lipid bilayers, with their hydrophilic ends oriented toward the watery medium and their hydrophobic ends shielded from the water. (britannica.com)
  • Phospholipid molecules, like molecules of many lipids, are composed of a hydrophilic "head" and one or more hydrophobic "tails. (britannica.com)
  • Biological bilayers are usually composed of amphiphilic phospholipids that have a hydrophilic phosphate head and a hydrophobic tail consisting of two fatty acid chains. (wikipedia.org)
  • In phospholipid bilayers the phosphate group is located within this hydrated region, approximately 0.5 nm outside the hydrophobic core. (wikipedia.org)
  • In membrane biology, fusion is the process by which two initially distinct lipid bilayers merge their hydrophobic cores, resulting in one interconnected structure. (wikipedia.org)
  • Integral proteins extend through the lipid bilayer to make contact with the interior of the cell, where their hydrophobic regions are protected from water. (reference.com)
  • We find that the adsorption of hIAPP to POPC bilayer is mainly initiated from the C-terminal region and the peptide adopts a helical structure with multiple binding orientations, while the adsorption to POPG bilayer is mostly initiated from the N-terminal region and hIAPP displays one preferential binding orientation, with its hydrophobic residues exposed to water. (hindawi.com)
  • Bilayers supported by hydrophobic materials (PTFE, polycarbonate, nylon, and silanised silver) had optimal resistance (14-19 GΩ) and capacitance (0.8-1.6 μ F) values whereas those with low hydrophobicity did not form BLMs (PVDF) or were short-lived (unsilanised silver). (hindawi.com)
  • Bilayers on thicker, more tortuous, and hydrophobic materials produced higher current levels. (hindawi.com)
  • A biological bilayer lipid membrane (BLM) is approximately four nanometres thick consisting of two adjacent monolayer sheets, each composed of molecules with hydrophilic headgroups exposed to water and acyl chains buried into the hydrophobic membrane interior. (hindawi.com)
  • A phospholipid with two hydrophobic tails will prevent the lipid in forming a circular fashion. (biology-online.org)
  • The simplest way for phospholipids to 'hide' their hydrophobic tails is the lipid bilayer configuration. (biology-online.org)
  • The average azimuthal rotation, ρ, is 235°, which results in burial of hydrophobic residues in the bilayer. (rcsb.org)
  • Hydrophobic matching, in which transmembrane proteins cause the surrounding lipid bilayer to adjust its thickness to match the hydrophobic surface of the protein, is a commonly accepted idea in biophysics, but one that until now has not been experimentally tested. (rice.edu)
  • The data also demonstrate that the neighboring β-strands associate upon insertion into the hydrophobic core of the lipid bilayer. (uva.nl)
  • Spontaneously translocating lipid-coated hydrophobic gold nanoparticles open doors for new biotechnology applications. (sciencemag.org)
  • Next, I highlight the path to identifying a new class of membrane proteins that reside and function within hydrophobic lipid bilayers. (rupress.org)
  • Lipid bilayers form automatically from phospholipids by self-assembly . (wikipedia.org)
  • These water-fearing tails will effectively orient the adjacent phospholipids into a bilayer position. (biology-online.org)
  • Useful structural information can nevertheless be obtained by diffraction methods because multilamellar bilayers (liquid crystals) obtained from phospholipids by dispersal in water or by deposition on surfaces are highly periodic along the bilayer normal. (uci.edu)
  • Simulation of the spontaneous aggregation of phospholipids into bilayers. (semanticscholar.org)
  • Phase behavior and structural properties were examined for phospholipid bilayers having different headgroups (DMPC, DMPS and DMPE) with added n-alkanes to study effect of flexible additives. (sigmaaldrich.com)
  • The results of X-ray diffraction show that the enthalpic stabilization due to enhanced packing of acyl chains of the lipid by alkanes in the gel phase causes the headgroup-dependent change in the phase transition behavior. (sigmaaldrich.com)
  • J. M. Rodgers, J. Sorensen, F. J. M. de Meyer, B. Schiott, and B. Smit, Understanding the Phase Behavior of Coarse-Grained Model Lipid Bilayers through Computational Calorimetry J. Phys. (berkeley.edu)
  • We study the phase behavior of saturated lipids as a function of temperature and tail length for two coarse-grained models: the soft-repulsive model typically employed with dissipative particle dynamics (DPD) and the MARTINI model. (berkeley.edu)
  • In addition to GUVs, binding and induced mixing behavior of NLPs was also observed on planar, supported lipid multibilayers. (osti.gov)
  • From a mathematical point-of-view, a particularly troubling aspect of lipid membrane behavior is its fluidity. (cornell.edu)
  • This thesis characterizes the electrowetting behavior of systems containing lipid bilayers (e.g. contact angle as a function of voltage), as well as other physical and electrical properties, including lipid bilayer thickness in response to applied electrostatic pressure, lipid bilayer conductivity under applied electric fields, and changes in lipid bilayer thickness with respect to time between voltage transitions. (tufts.edu)
  • These observations have important implications for how phase behavior determined by bulk methods using dense, multilamellar lipid bilayers are linked to phase separation in giant, unilamellar lipid bilayers as observed by microscopy. (utexas.edu)
  • This bilayer is often described as a fluid mosaic model because of the variety of molecules that are found within the cell membrane. (coursehero.com)
  • The cell membrane is a phospholipid bilayer studded with different kinds of proteins. (coursehero.com)
  • Here, the high-resolution structures of the homologous 22-residue long AMPs piscidin 1 (p1) and piscidin 3 (p3) are determined in fluid-phase 3:1 phosphatidylcholine/phosphatidylglycerol (PC/PG) and 1:1 phosphatidylethanolamine/phosphatidylglycerol (PE/PG) bilayers to identify molecular features important for membrane destabilization in bacterial cell membrane mimics. (rcsb.org)
  • In this Milestones article, I review some of the key experiments that led to our current understanding of the cell membrane as a lipid bilayer that solvates proteins that span the membrane. (rupress.org)
  • The past 100 years take us from a time when we did not know the lipid bilayer and integral membrane proteins existed to the present, where the structure of membrane proteins, even in the context of the cell membrane, is becoming more and more accessible. (rupress.org)
  • The fluorescence decay of membrane lipid bilayer probes are influenced by the environment of the probe and therefore by the properties of the bilayer in which it resides. (spie.org)
  • For more fluid bilayers of DOPC the conductance gradually increases until the bilayer disintegrates, which has also been observed for cytotoxic amyloid oligomers. (soton.ac.uk)
  • This molecular dynamics simulation of a dioleoyl-phosphatidylcholine (DOPC) bilayer in excess water demonstrates the extreme thermal motion of fluid lipid bilayers. (uci.edu)
  • A representation of the liquid-crystallographic structure of an Lα-phase dioleoylphosphatidylcholine (DOPC) bilayer ( 8 ) is shown in Figure 2A . (uci.edu)
  • This approach has been used to locate newly synthesized lipid probes in DOPC bilayers. (diva-portal.org)
  • In this chapter we review recent work by the writer and coworkers on various aspects of the mechanics and physics of lipid bilayers. (springer.com)
  • Formation of supported lipid bilayer (SLB) and additional structures of Escherichia coli ( E. coli ) lipids were investigated with fluorescence microscopy and atomic force microscopy. (frontiersin.org)
  • The most disruptive nanospheres were shown by confocal fluorescence microscopy to accumulate at the bilayer surface, and we demonstrated that a fraction of these particles translocate across the lipid bilayer, suggesting that passive uptake of nanoparticles may contribute to cellular uptake. (soton.ac.uk)
  • Using several different approaches which included information on fluorescence quantum yield, polarization, spectra and diffusion properties of a fluorescent derivative of PI(4,5)P2 (TopFluor(TF)-PI(4,5)P2), we show that Ca(2+) promotes PI(4,5)P2 clustering in lipid bilayers at physiological concentrations of both Ca(2+) and PI(4,5)P2. (nih.gov)
  • A method for spanning bilayers over these PDMS microcavity arrays was developed and lipid diffusion dynamics over the cavities was assessed using Fluorescence Lifetime Correlation Spectroscopy (FLCS). (dcu.ie)
  • The "sampling" of environmental heterogeneity will depend on the intrinsic fluorescence lifetime, the lipid rate of motion and fluorophore charge and shape factors. (spie.org)
  • Our results are the first to demonstrate the transfer of a MP from NABBs to a different lipid bilayer without involving vesicle fusion. (rupress.org)
  • With various lipids, originating from biological sources, such as egg yolk phosphatidylcholine, soybean phosphatidylcholine or bovine brain phosphatidylserine, spontaneously fluctuating channels could be observed. (springer.com)
  • Lipid bilayers are important in biological cells . (wikipedia.org)
  • In Chapter 5, I provide an outlook of how our work has increased the biological relevance of the supported lipid bilayer and has increased its utility for studying a wide range of biological processes. (cornell.edu)
  • The different compounds were chosen according to their different biological functions, namely (i) antioxidant activity against lipid peroxidation, (ii) antimicrobial activity with the possibility of trans-membrane pore formation, and (iii) inhibition of enzymes involved in Alzheimer's disease. (archives-ouvertes.fr)
  • Artificial bilayers, which are created in a laboratory for ion channel insertion and study, are attractive since the measurement is much easier and the experimenter has greater control over the surrounding biological environment. (universityofcalifornia.edu)
  • Whatever the mechanism of calcium-induced fusion, the initial interaction is clearly electrostatic, since zwitterionic lipids are not susceptible to this effect. (wikipedia.org)
  • Cell-free expression systems in combination with nanodiscs (discoidal lipid bilayer particles) offer a valuable approach to probe membrane proteins in situ. (fz-juelich.de)
  • This study shows a lateral heterogeneity in the mixed stratum corneum lipid monolayers. (lu.se)
  • Calcium has been shown to induce clustering of PI(4,5)P2 at high and non-physiological concentrations of both the divalent ion and the phosphatidylinositol, or on supported lipid monolayers. (nih.gov)
  • Plasmid-lipid particles which are useful for transfection of cells in vitro or in vivo are described. (google.com)
  • c) removing said detergent from said solution of step (b) to provide a solution of serum-stable plasmid-lipid particles, wherein said plasmid is encapsulated in a lipid bilayer and said particles are resistant to degradation in serum, and wherein the particles have a diameter ranging from about 50 to about 150 nm. (google.com)
  • Here, the question is addressed how the adhesion energy between sup ported lipid bilayers and silica particles helps to understand nanoparticle uptake. (uni-muenchen.de)
  • Here, we report the successful delivery of an ion channel from these particles, called nanoscale apolipoprotein-bound bilayers (NABBs), to a distinct, continuous lipid bilayer that will allow both ensemble assays, made possible by the soluble NABB platform, and single-molecule assays, to be performed from the same biochemical preparation. (rupress.org)
  • Zou and McHaourab, 2010 ), there have not been any reports to confirm whether the NABB-embedded proteins can be safely transferred to other bilayers-a result that could extend the use of these particles further, as targeted delivery vehicles for MPs. (rupress.org)
  • article{a368ebbd-01f9-45be-9068-5afacea52e84, abstract = {In this work we show how hydrodynamic forces can be used to locally trap molecules in a supported lipid bilayer (SLB). (lu.se)
  • Abstract: This thesis reports the first-time demonstration of lipid bilayers as reversibly wettable dielectrics in electrowetting systems and characterizes various physical and electrical properties of lipid bilayers, with the aim of assessing the capabilities and limitations of using these thin liquid films in electrowetting-powered microfluidic devices. (tufts.edu)
  • Included in this thesis is a new approach based on electronic energy transfer/migration (FRET/DDEM), which efficiently determines transversal positions of fluorescent molecules in lipid bilayers. (diva-portal.org)
  • This was related to the sterol affinity for unsaturated PL. In addition, the different sterol affinities of saturated di-palmitoyl-PC (DPPC) and PSM resulted in strongly promoted phase separation with PSM but only slight promotion with DPPC, especially in bilayers containing polyunsaturated PC. (doria.fi)
  • Integral membrane proteins function when incorporated into a lipid bilayer, and they are held tightly to the lipid bilayer with the help of an annular lipid shell. (wikipedia.org)
  • M. B. Forstner, C. K. Yee, A. N. Parikh and J. T. Groves, "Lipid Lateral Mobility and Membrane Phase Structure Modulation by Protein Binding," Journal of the American Chemical Society, Vol. 128, No. 47, 2006, pp. 15221-15227. (scirp.org)
  • The lipid bilayer is very thin compared to its lateral dimensions. (wikipedia.org)
  • These novel applications of CSLBs rely on previously unappreciated properties: the simultaneous fluidity of the bilayer, lateral mobility of inserted (linker) molecules and colloidal stability. (rsc.org)
  • A thorough investigation of the lateral organisation in a stratum corneum lipid model was undertaken. (lu.se)
  • In paper I, we have studied how sphingolipids with different head groups induced lateral segregation and altered acyl chain order in unsaturated fluid phosphatidylcholine (PC) bilayers. (doria.fi)
  • Here, we aimed to determine through spectroscopic methodologies if calcium plays a role in PI(4,5)P2 lateral distribution on lipid bilayers under physiological conditions. (nih.gov)
  • We conclude that aerolysin channels are produced by direct insertion of oligomers formed in solution, or assembled on the surface of the cell after binding to the receptor, and not by lateral diffusion of the monomer after it enters the lipid bilayer. (epfl.ch)
  • Thickness Mismatch of Coexisting Liquid Phases in Noncanonical Lipid Bilayers. (sigmaaldrich.com)
  • Lipid composition also determines whether a membrane demixes into coexisting liquid-crystalline phases. (sigmaaldrich.com)
  • In both phases the lipid molecules are constrained to the two dimensional plane of the membrane, but in liquid phase bilayers the molecules diffuse freely within this plane. (primidi.com)
  • As an example for the coarse grained lipid model introduced by Lenz and Schmid, we calculate the Poisson's ratio in the gel, fluid, and interdigitated phases. (frontiersin.org)
  • The lipid system experimentally presents four different bilayer phases - subgel, gel, ripple, and fluid - and the DPD model describes all of these phases structurally while MARTINI describes a single order-disorder transition between the gel and the fluid phases. (berkeley.edu)
  • We also study the lipid dynamics displayed by these models for the various phases, discussing this dynamics with relation to fidelity to experiment and computational efficiency. (berkeley.edu)
  • In the thesis, we combine PAINT with a phase sensitive dye, Merocyanine 540, to enable nanoscale observation of phase separation on supported lipid bilayers of mixed liquid/gel phases. (upenn.edu)
  • Pure Lipid Pores in Unmodified Planar Bilayer Lipid Membrane at the Phase Transition from the Liquid Crystalline State to the Gel State (V.F. Antonov et al . (elsevier.com)
  • Lipid composition dictates membrane thickness, which in turn can influence membrane protein activity. (sigmaaldrich.com)
  • However, no influence of the nanoparticles on the area per lipid or the membrane thickness was observed. (tu-darmstadt.de)
  • This study provides mechanistic insights into the different interaction behaviors of hIAPP with zwitterionic and anionic lipid bilayers. (hindawi.com)
  • In some cases, the hydrated region can extend much further, for instance in lipids with a large protein or long sugar chain grafted to the head. (wikipedia.org)
  • Unlike other protein groups, these can be removed without causing any damage to the lipid bilayer. (reference.com)
  • Our results show that voltage sensors adopt transmembrane orientations, cause a modest reshaping of the surrounding lipid bilayer, and that water molecules intimately interact with the protein within the membrane. (aps.org)
  • Using electrophysiological methods we have demonstrated that spherical silica nanoparticles, under development for intracellular drug delivery, are able to permeabilize protein-free lipid bilayers as a function of size and surface charge. (soton.ac.uk)
  • The fluid aspect of the mosaic model is the free movement of both lipid and protein components within a membrane so that the movement occurs in the lipid bilayer. (coursehero.com)
  • Customization of the system and offering of a lipid support (here: nanodiscs) enable membrane protein expression in a high yield. (fz-juelich.de)
  • We also include a study on the peptide melittin as an example of the type of protein-lipid system we want to understand better. (rice.edu)
  • we demonstrated that polyP modulates TRPM8 channels directly, using the purified protein from mammalian cells incorporated in planar lipid bilayers. (jneurosci.org)
  • The in situ coupling of the anti-BSA antibody as a model protein to the amine moiety of phosphatidylethanolamine (PE) in a lipid bilayer by the amine coupling method allowed us to design an antigen (BSA)-sensitive interface, in which the integrated current, rather than the frequency of channel event, can be used as an analytical signal. (go.jp)
  • Membrane protein folding involves the favorable association of non-polar protein interfaces amidst an excess of similarly non-polar lipid solvent ( Popot and Engelman, 1990 ). (elifesciences.org)
  • We imaged active translocases in lipid bilayers as a function of precursor protein species, nucleotide species, and stage of translocation using atomic force microscopy (AFM). (sciencemag.org)
  • during protein export, it makes contact with SecYEG, precursor proteins, lipids, and chaperone SecB and converts chemical energy into mechanical work on the precursor. (sciencemag.org)
  • The trans-membrane protein - proteorhodopsin (pR) has been incorporated into supported lipid bilayers (SLB). (whiterose.ac.uk)
  • More recently we have been able to show that the protein-lipid interface itself can act as a source of fluorophore heterogeneity. (spie.org)
  • Leicester Research Archive: Structure of outer membrane protein G in lipid bilayers. (le.ac.uk)
  • Here, we report the structure of outer membrane protein G investigated in bilayers of E. coli lipid extracts by magic-angle-spinning NMR. (le.ac.uk)
  • Here we report the generation of such bilayers and their relevant biophysical properties and in particular the accessibility of PI-(4,5)-P 2 for protein binding. (figshare.com)
  • Bilayers were formed in a pH-dependent manner and were characterized by the accessibility of PI-(4,5)-P 2 on the SLB surface as shown by the interaction with the PI-(4,5)-P 2 binding domain of the cortical membrane-cytoskeleton linker protein ezrin. (figshare.com)
  • If this fusion proceeds completely through both leaflets of both bilayers, an aqueous bridge is formed and the internal contents of the two structures can mix. (wikipedia.org)
  • The aqueous contents enclosed by each bilayer also remain separated. (wikipedia.org)
  • Bilayer arrays can be formed by using a technique similar to the regulated attachment method, where mechanical force is used to bring adjacent aqueous lenses in contact. (spie.org)
  • We describe a system that provides a rapid and simple way of forming suspended lipid bilayers within a microfluidic platform from an aqueous droplet. (soton.ac.uk)
  • The nanoparticles perturbed the density profiles of the bilayers and reduce dlipid order in their close neighborhood, but only in the lipid layer facing them. (tu-darmstadt.de)
  • Discoidal lipoproteins are a novel class of nanoparticles for studying membrane proteins (MPs) in a soluble, native lipid environment, using assays that have not been traditionally applied to transmembrane proteins. (rupress.org)
  • Physiologically, the alteration of fatty acid composition tends to maintain constant bilayer fluidity at various growth temperatures (27). (springer.com)
  • We find that the insertion of lipopolymers in the bilayer can affect its homogeneity and fluidity. (rsc.org)
  • A particularly important example in animal cells is cholesterol, which helps strengthen the bilayer and decrease its permeability. (wikipedia.org)
  • Using the voltage-dependent Na + channel as an example, we show in this chapter that, even though the lipid bilayer system offers many experimental advantages, the determination and the analysis of single-channel conductance and permeability data are not always simple. (springer.com)
  • This artificial lipid membrane system is biochemically stable, well defined and homogeneous. (fz-juelich.de)
  • Yet, as a technology, artificial lipid bilayers are also characterized by low throughput and relatively high costs associated with its manual technique. (universityofcalifornia.edu)
  • 7. A method in accordance with claim 1, wherein said non-cationic lipids are selected from the group consisting of DOPE, POPC, EPC and combinations thereof. (google.com)
  • 11. A method in accordance with claim 10, wherein said plasmid-lipid particle comprises a plasmid, DODAC, POPC and a PEG-Ceramide selected from the group consisting of PEG-Cer-C 20 and PEG-Cer-C 14 . (google.com)
  • hIAPP monomer inserts into POPC lipid bilayers more readily than into POPG bilayers. (hindawi.com)
  • The stronger binding state was reached via the metastable weaker one and only for the cationic nanoparticle on the two negatively charged bilayers (POPC/POPG and POPG). (tu-darmstadt.de)
  • We investigated whether ion channels could be transferred from NABBs, which are planar, small bilayers made with POPC and zebrafish apolipoprotein A-I (apo A-I), to BLMs comprising of POPE/POPG (PE/PG) lipids. (rupress.org)
  • Experimentally, it has been shown that as chain length and concentration of alcohols near a membrane increase, the area per lipid expands, increasing the likelihood of permeation. (aps.org)
  • We obtain agreement with experiments for area per lipid head group and deuterium order parameter. (aps.org)
  • For example, phase separation and membrane fusion of lipid bilayers containing phosphatidylserine is caused by Ca 2+ ( Silvius and Gagne, 1984a , b ). (frontiersin.org)
  • Determining the origin of these effects and the impact of other bilayer features, such as lipid phase separation, on the interfacial assembly of NPs would enable the design of NPs for applications that require NP assembly, such as photothermal therapy. (aiche.org)
  • Given that this is the first example of visualization of nanoscale phase separation of lipid bilayers using an optical microscope, we further looked into the kinetics of MC540 monomer dimer equilibrium in lipid bilayers using single molecule intensity time trajectory analysis and polarization dependent imaging. (upenn.edu)
  • Because bilayers define the boundaries of the cell and its compartments, these membrane proteins are involved in many intra- and inter-cellular signaling processes. (wikipedia.org)
  • Certain kinds of membrane proteins are involved in the process of fusing two bilayers together. (wikipedia.org)
  • Lipids impart conformational stability and modulation on membrane proteins, which is closely tied to their function. (cornell.edu)
  • In this work I discuss development of additional function for the SLB platform in two key areas: 1) generation of patterned supported lipid bilayers that mimic membrane heterogeneities such as the "lipid raft" to evaluate associated dynamics and 2) the inclusion of membrane proteins in a robust and simplified manner. (cornell.edu)
  • In Chapter 3, I characterize a novel technique for delivery of membrane proteins from cell blebs into a cushioned supported lipid bilayer. (cornell.edu)
  • A. Agrawal, D.J. Steigmann, A model for surface diffusion of trans-membrane proteins on lipid bilayers. (springer.com)
  • Microdroplets, containing membrane proteins, are injected onto an electrode positioned above an aperture machined through a conical cavity that is filled with a lipid-alkane solution. (soton.ac.uk)
  • Now, research is turning toward a physical understanding of the reactions of membrane proteins and lipids in this unique and incredibly complex solvent environment. (rupress.org)
  • Finally, I discuss current research of membrane proteins in lipid bilayers, highlighting the key challenges and complexities of studying proteins in a solvent environment that is self-assembling and has its own structural properties and increased chemical complexity. (rupress.org)
  • Exchange of lipids, metabolites or proteins across the lipid bilayer can occur through integral membrane proteins - as demonstrated for peroxisomes, mitochondria or chloroplasts. (biologists.org)
  • Curvature-induced Sorting of Bilayer Membrane Constituents and Formation of Membrane Rafts (V. Kralj-Igliè, P. Veraniè). (elsevier.com)
  • In Chapter 4, I detail patterning of two-phase supported lipid bilayers as a mimic for lipid rafts. (cornell.edu)
  • The existence of lipid rafts has been under debates for decades due to the lack of a tool to directly visualize them in live cells. (upenn.edu)
  • The bilayer can adopt a solid gel phase state at lower temperatures but undergo phase transition to a fluid state at higher temperatures, and the chemical properties of the lipids' tails influence at which temperature this happens. (wikipedia.org)
  • The assembly can be controlled to give a densely packed single layer of RNA polyhedrons at the fluid lipid bilayer surface. (chalmers.se)
  • It also describes recent results from the use of these methods for determining the disposition of helical peptides in fluid bilayers. (uci.edu)
  • The need for quantitatively useful structural information for fluid bilayer systems such as this stimulated the development of the methods described below. (uci.edu)
  • Unfortunately, the high thermal disorder of fluid bilayers precludes atomic-resolution three-dimensional crystallographic images. (uci.edu)
  • The 'structure' of a fluid bilayer is consequently defined operationally as the time-averaged spatial distributions of the principal structural (quasi-molecular) groups of the lipid (carbonyls, phosphates, etc.) projected onto an axis normal to the bilayer plane ( 3 ), as shown in Figure 1 for the phosphate group of a phosphatidylycholine molecule. (uci.edu)
  • Complete structural images of this sort which account for all of the constituents of the unit cell can be obtained using a joint refinement procedure developed in this laboratory that allows one to combine x-ray and neutron data to arrive at fully-resolved images of fluid bilayers ( 3 , 4 , 5 , 6 , 7 , 8 ). (uci.edu)
  • Lipid bilayers are ideally suited to this role, even though they are only a few nanometers in width, because they are impermeable to most water-soluble (hydrophilic) molecules. (wikipedia.org)
  • The first region on either side of the bilayer is the hydrophilic headgroup. (wikipedia.org)
  • The lipid bilayers stop most water-soluble (hydrophilic) molecules passing through. (wikipedia.org)
  • Hydrophilic pores are formed in peptide free lipid bilayers under mechanical stress. (semanticscholar.org)
  • Small angle neutron diffraction from flat lipid bilayers that are hydrated through water vapor has been employed to eliminate possible artefacts of the membrane curvature and the alcohol's membrane-water partitioning. (mdpi.com)
  • The minimization of induced curvature near topological features, such as boundaries between stiff and flexible phase-separated bilayer domains, enhances NP adsorption. (aiche.org)
  • The phase occurs in a narrow composition range reflecting the delicate balance in keeping the slightly negative curvature of the bilayer. (lu.se)
  • The amphiphilic packing concept was shown to be a useful tool in predicting and compensating for changes in curvature of the monoolein bilayer. (lu.se)
  • A characteristic of nearly all organisms is their ability to accomodate the fatty acid composition of their lipids to growth temperature (7,8,10,23). (springer.com)
  • 4.Electrical methods for determining surface charge density and electrolyte composition at the lipid bilayer solution interface. (elsevier.com)
  • Specifically, we have studied the influence of different particle properties (roughness, surface charge, chemical composition, polymer coating) on the quality and mobility of the supported bilayer. (rsc.org)
  • These results highlight the robustness of a membrane's liquid-ordered phase to be thicker than the liquid-disordered phase, regardless of the membrane's lipid composition. (sigmaaldrich.com)
  • The channel activity of gramicidin A in lipid bilayers is tunable by adjusting the membrane composition. (go.jp)
  • The ability of ion channels to function in BLMs was assessed using a method recently reported to improve the efficiency of proteoliposome incorporation into PTFE-supported bilayers. (hindawi.com)
  • Incorporation of polymyxin lowers the lipid phase transition by 10 degrees C. One polymyxin is found to bind five phosphatidylglycerol molecules. (nih.gov)
  • Incorporation of ion transporting molecules into the supported bilayers is also investigated by EIS. (dcu.ie)
  • A time-dependent reduction of PI-(4,5)-P 2 levels in the upper leaflet of SLBs was observed, which could be effectively inhibited by the incorporation of a negatively charged lipid such as phosphatidylserine. (figshare.com)
  • The presence of the uncharged headgroup phosphatidylethanolamine (PE) increases fusion when incorporated into a phosphatidylcholine bilayer. (wikipedia.org)
  • Spontaneous channel activity could not be observed in planar bilayers made from synthetic lipids, such as 1,2 diphytanoyl 3-sn-phosphatidylcholine. (springer.com)
  • Heterodimers induce aggregation of negatively charged bilayers composed of phosphatidylglycerol and do not induce aggregation of neutral bilayers composed of phosphatidylcholine. (ovid.com)
  • Why is it that things like phosphlipids and glycosphingolipids (like sphingomyelin and glycosphingolipids) form lipid bilayers when theyre exposed to water, whereas some things form micelles instead? (biology-online.org)
  • The first part focuses on the localisation of probes in lipid/polymeric bilayers and in G M1 micelles. (diva-portal.org)
  • The parallel packing of the peptide in the lipid bilayer differs from the antiparallel dimer found in DPC micelles and may be stabilized by its strong amphipathic character, which should facilitate its insertion into the amphipathic lipid bilayer. (rcsb.org)
  • Voltage-induced nonconductive pre-pores and metastable single pores in unmodified planar lipid bilayer. (semanticscholar.org)
  • We treated the lipid bilayer and the cytoskeleton as two distinct components and developed a unique whole-cell model of the RBC, using dissipative particle dynamics (DPD). (pnas.org)
  • Due to diffusion limitations, an adaptation of the replica exchange molecular dynamics algorithm is used to compute robust, low energy configurations of mixed bilayers. (aiche.org)
  • In this study, we report how the lipid and ligand molecules influence the conformational dynamics of the membrane-bound SSTR2. (nature.com)
  • Additionally, we studied the conformational dynamics of N- and C-terminal regions of SSTR2 in the presence and absence of the lipid bilayer. (nature.com)
  • The 100-ns-long molecular dynamics simulation at constant pressure (1 atm) and at a temperature of 50°C of 64 lipid molecules and 64 x 23 water molecules lack a slow water reorientation correlation component in the ns time scale. (diva-portal.org)
  • In fact with regard to the relative degree of environmental heterogeneity sampled by the fluorophore it may be better to make such types of comparisons at the same respective rates of lipid motion since the rate of lipid motion is a key factor governing the sampling of environmental heterogeneity. (spie.org)
  • Experiments on bilayers often require advanced techniques like electron microscopy and atomic force microscopy. (wikipedia.org)
  • This layer is predominantly composed of dead skin cells-corneocytes-embedded in a rich lipid matrix composed of ceramides, cholesterol, and free fatty acids. (aiche.org)
  • Furthermore, examination of the hydrogen bonding network in the bilayer reveals a reduction in ceramide-ceramide hydrogen bonding due to the presence of cholesterol. (aiche.org)
  • The additivity of the packing parameters of cholesterol and PZPC explains their cohabitation in a planar bilayer. (rsc.org)
  • The main constitutents of the stratum corneum lipids are ceramides, free fatty acids and cholesterol. (lu.se)
  • 1.5 × 10 -20 J/lipid at the compositions observed, decreasing as the relative cholesterol concentration was increased. (osti.gov)
  • Furthermore, quartz crystal microbalance measurements revealed that cholesterol affects bilayer adsorption to the solid support. (figshare.com)
  • 6. A method in accordance with claim 1, wherein said cationic lipids are selected from the group consisting of DODAC, DDAB, DOTAP, DOTMA, DOSPA, DOGS, DC-Chol and combinations thereof. (google.com)
  • 15. A method in accordance with claim 10, wherein said non-cationic lipids comprise a polyethylene glycol-lipid conjugate. (google.com)
  • Piercing Lipid Bilayers with Peptides (E.E. Ambroggio et al . (elsevier.com)
  • amyloid peptides, are observed for rigid sterol-containing bilayers. (soton.ac.uk)
  • A molecular understanding of the interaction of peptides and proteins with lipid bilayers requires experimental knowledge of the structure of the membrane bilayer, the transbilayer location of bound peptides, the structures the peptides adopt, and the changes that occur in the bilayer structure as a result of partitioning. (uci.edu)
  • The extension of our approach to other binary or ternary lipid model or natural systems provides a promising new super-resolution strategy. (upenn.edu)
  • We investigate the structural changes to lipid membrane that ensue from the addition of aliphatic alcohols with various alkyl tail lengths. (mdpi.com)
  • Both the systems were compared to understand the influence of lipid molecules in the formation of secondary structural domains by these extracellular regions. (nature.com)
  • The comparative study revealed that the secondary structural elements formed by C-terminal residues in presence of lipid molecules is crucial for the functioning of SSTR2. (nature.com)
  • Our study results highlight the structural complexities involved in the functioning of SSTR upon binding with the ligands in the presence and absence of lipid bilayer, which is essential for designing novel drug targets. (nature.com)
  • These structural findings reveal that voltage sensors have evolved to interact with the lipid membrane while keeping the energetic and structural perturbations to a minimum, and that water penetrates into the membrane to hydrate charged residues and shape the transmembrane electric field. (aps.org)
  • That is, they give the probability of finding a particular structural group at a specific location in the bilayer or the number of groups per unit volume at a given location. (uci.edu)
  • The areas under the peaks are equal to the number of structural groups per lipid molecule ( e.g . two methyls, 28 methylenes, one phosphate). (uci.edu)
  • Although the structural image of Figure 2A was obtained at low hydration, 5.4 waters per lipid, recent work in our laboratory demonstrates that the overall structure changes in only subtle ways as the water content is increased ( 9 ). (uci.edu)
  • The vast diversity of lipid species found in cells suggests that structural variation of lipids is essential for the normal function of the cell. (doria.fi)
  • Using this approach in the example of increasing levels of unsaturation our results suggest that unsaturation introduces structural diversity into lipid bilayers. (spie.org)
  • Increasing evidence suggests that the interaction of human islet amyloid polypeptide (hIAPP) with lipids may facilitate hIAPP aggregation and cause the death of pancreatic islet β -cells. (hindawi.com)
  • We report that the action of the heterodimeric phospholipases A2 (PLA2s) from Vipera nikolskii, which comprises enzymatically active basic subunit and inactive acidic PLA2 homologue, on the lipid bilayer results in the aggregation and stacking of bilayers. (ovid.com)
  • Aggregation of bilayers is possible because both subunits of the V. nikolskii heterodimer contain a membrane-binding site (also known as IBS). (ovid.com)
  • In spite of this, the use of laterally mobile lipid bilayers to control RNA three-dimensional nanostructure formation on surfaces remains largely unexplored. (chalmers.se)
  • The formation of the BLM depends solely on the device geometry and leads to spontaneous formation of lipid bilayers simply by dispensing droplets of buffer. (soton.ac.uk)
  • Formation of native β-strand contacts in folding experiments required the lipid membrane. (uva.nl)
  • Simulation of pore formation in lipid bilayers by mechanical stress and electric fields. (semanticscholar.org)