A group of peptides characterized by length of 1-2 dozen residues with a high proportion of them being non-proteinogenic, notably alpha-aminoisobutyric acid (Aib) and isovaline, and have a C-terminal amino alcohol and N terminal alkyl group. They are found in FUNGI and some are ANTI-INFECTIVE AGENTS. They form channels or pores in target organisms. The term is a contraction of peptide-Aib-alcohol.
Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.
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.
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.
Chemical agents that increase the permeability of biological or artificial lipid membranes to specific ions. Most ionophores are relatively small organic molecules that act as mobile carriers within membranes or coalesce to form ion permeable channels across membranes. Many are antibiotics, and many act as uncoupling agents by short-circuiting the proton gradient across mitochondrial membranes.
An antihelmintic that is active against most tapeworms. (From Martindale, The Extra Pharmacopoeia, 30th ed, p48)
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.
The physical characteristics and processes of biological systems.
Eight-carbon saturated hydrocarbon group of the methane series. Include isomers and derivatives.
The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.
The ability of a substrate to allow the passage of ELECTRONS.
A sulfuric acid dimer, formed by disulfide linkage. This compound has been used to prolong coagulation time and as an antidote in cyanide poisoning.
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.
A mitosporic fungal genus frequently found in soil and on wood. It is sometimes used for controlling pathogenic fungi. Its teleomorph is HYPOCREA.
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)
The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.
Substances that reduce the growth or reproduction of BACTERIA.
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.
Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.
Heterocyclic compounds in which an oxygen is attached to a cyclic nitrogen.
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.
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 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.
Glycosides of GLUCURONIC ACID formed by the reaction of URIDINE DIPHOSPHATE GLUCURONIC ACID with certain endogenous and exogenous substances. Their formation is important for the detoxification of drugs, steroid excretion and BILIRUBIN metabolism to a more water-soluble compound that can be eliminated in the URINE and BILE.
A family of enzymes accepting a wide range of substrates, including phenols, alcohols, amines, and fatty acids. They function as drug-metabolizing enzymes that catalyze the conjugation of UDPglucuronic acid to a variety of endogenous and exogenous compounds. EC
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.
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.
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)
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)
The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
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.
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 low-energy attractive force between hydrogen and another element. It plays a major role in determining the properties of water, proteins, and other compounds.
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).
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)
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)
A representation, generally small in scale, to show the structure, construction, or appearance of something. (From Random House Unabridged Dictionary, 2d ed)
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).
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.
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 characteristic three-dimensional shape of a molecule.
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)
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.
Computer-based representation of physical systems and phenomena such as chemical processes.
The accumulation of an electric charge on a object
The physical phenomena describing the structure and properties of atoms and molecules, and their reaction and interaction processes.
Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.
The study of CHEMICAL PHENOMENA and processes in terms of the underlying PHYSICAL PHENOMENA and processes.
The rate dynamics in chemical or physical systems.
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 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.
A colorless, flammable liquid used in the manufacture of FORMALDEHYDE and ACETIC ACID, in chemical synthesis, antifreeze, and as a solvent. Ingestion of methanol is toxic and may cause blindness.
Solution titration in which the end point is read from the electrode-potential variations with the concentrations of potential determining ions. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
A group of atoms or molecules attached to other molecules or cellular structures and used in studying the properties of these molecules and structures. Radioactive DNA or RNA sequences are used in MOLECULAR GENETICS to detect the presence of a complementary sequence by NUCLEIC ACID HYBRIDIZATION.
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.
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 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.
A non-essential amino acid that is synthesized from GLUTAMIC ACID. It is an essential component of COLLAGEN and is important for proper functioning of joints and tendons.
The chemical and physical integrity of a pharmaceutical product.
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.
Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.
The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.
Organic compounds containing the -CO-NH2 radical. Amides are derived from acids by replacement of -OH by -NH2 or from ammonia by the replacement of H by an acyl group. (From Grant & Hackh's Chemical Dictionary, 5th ed)
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)
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.
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 first chemical element in the periodic table. It has the atomic symbol H, atomic number 1, and atomic weight [1.00784; 1.00811]. It exists, under normal conditions, as a colorless, odorless, tasteless, diatomic gas. Hydrogen ions are PROTONS. Besides the common H1 isotope, hydrogen exists as the stable isotope DEUTERIUM and the unstable, radioactive isotope TRITIUM.
Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough.
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.
Deuterium. The stable isotope of hydrogen. It has one neutron and one proton in the nucleus.
A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.
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)
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.
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.
The formation of crystalline substances from solutions or melts. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
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.
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.
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)
Elements of limited time intervals, contributing to particular results or situations.
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.
An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.
The parts of a macromolecule that directly participate in its specific combination with another molecule.

The role of proline and glycine in determining the backbone flexibility of a channel-forming peptide. (1/201)

Alamethicin is a helical 20-amino acid voltage-gated channel-forming peptide, which is known to exhibit segmental flexibility in solution along its backbone near alpha-methylalanine (MeA)-10 and Gly-11. In an alpha-helical configuration, MeA at position 10 would normally hydrogen-bond with position 14, but the presence of proline at this position prevents the formation of this interhelical hydrogen bond. To determine whether the presence of proline at position 14 contributes to the flexibility of this helix, two analogs of alamethicin were synthesized, one with proline 14 replaced by alanine and another with both proline 14 and glycine 11 replaced by alanine. The C-termini of these peptides were derivatized with a proxyl nitroxide, and paramagnetic enhancements produced by the nitroxide on the Calpha protons were used to estimate r-6 weighted distances between the nitroxide and the backbone protons. When compared to native alamethicin, the analog lacking proline 14 exhibited similar C-terminal to Calpha proton distances, indicating that substitution of proline alone does not alter the flexibility of this helix; however, the subsequent removal of glycine 11 resulted in a significant increase in the averaged distances between the C- and N-termini. Thus, the G-X-X-P motif found in alamethicin appears to be largely responsible for mediating high-amplitude bending motions that have been observed in the central helical domain of alamethicin in methanol. To determine whether these substitutions alter the channel behavior of alamethicin, the macroscopic and single-channel currents produced by these analogs were compared. Although the substitution of the G-X-X-P motif produces channels with altered characteristics, this motif is not essential to achieve voltage-dependent gating or alamethicin-like behavior.  (+info)

An alamethicin channel in a lipid bilayer: molecular dynamics simulations. (2/201)

We present the results of 2-ns molecular dynamics (MD) simulations of a hexameric bundle of Alm helices in a 1-palmitoyl-2-oleoylphosphatidylcholine bilayer. These simulations explore the dynamic properties of a model of a helix bundle channel in a complete phospholipid bilayer in an aqueous environment. We explore the stability and conformational dynamics of the bundle in a phospholipid bilayer. We also investigate the effect on bundle stability of the ionization state of the ring of Glu18 side chains. If all of the Glu18 side chains are ionised, the bundle is unstable; if none of the Glu18 side chains are ionized, the bundle is stable. pKA calculations suggest that either zero or one ionized Glu18 is present at neutral pH, correlating with the stable form of the helix bundle. The structural and dynamic properties of water in this model channel were examined. As in earlier in vacuo simulations (Breed et al., 1996 .Biophys. J. 70:1643-1661), the dipole moments of water molecules within the pore were aligned antiparallel to the helix dipoles. This contributes to the stability of the helix bundle.  (+info)

Preferential transport of glutathione versus glutathione disulfide in rat liver microsomal vesicles. (3/201)

A bi-directional, saturable transport of glutathione (GSH) was found in rat liver microsomal vesicles. GSH transport could be inhibited by the anion transport blockers flufenamic acid and 4, 4'-diisothiocyanostilbene-2,2'-disulfonic acid. A part of GSH taken up by the vesicles was metabolized to glutathione disulfide (GSSG) in the lumen. Microsomal membrane was virtually nonpermeable toward GSSG; accordingly, GSSG generated in the microsomal lumen could hardly exit. Therefore, GSH transport, contrary to previous assumptions, is preferred in the endoplasmic reticulum, and GSSG entrapped and accumulated in the lumen creates the oxidized state of its redox buffer.  (+info)

Surface binding of alamethicin stabilizes its helical structure: molecular dynamics simulations. (4/201)

Alamethicin is an amphipathic alpha-helical peptide that forms ion channels. An early event in channel formation is believed to be the binding of alamethicin to the surface of a lipid bilayer. Molecular dynamics simulations are used to compare the structural and dynamic properties of alamethicin in water and alamethicin bound to the surface of a phosphatidylcholine bilayer. The bilayer surface simulation corresponded to a loosely bound alamethicin molecule that interacted with lipid headgroups but did not penetrate the hydrophobic core of the bilayer. Both simulations started with the peptide molecule in an alpha-helical conformation and lasted 2 ns. In water, the helix started to unfold after approximately 300 ps and by the end of the simulation only the N-terminal region of the peptide remained alpha-helical and the molecule had collapsed into a more compact form. At the surface of the bilayer, loss of helicity was restricted to the C-terminal third of the molecule and the rod-shaped structure of the peptide was retained. In the surface simulation about 10% of the peptide/water H-bonds were replaced by peptide/lipid H-bonds. These simulations suggest that some degree of stabilization of an amphipathic alpha-helix occurs at a bilayer surface even without interactions between hydrophobic side chains and the acyl chain core of the bilayer.  (+info)

C-terminally shortened alamethicin on templates: influence of the linkers on conductances. (5/201)

In order to test the influence of chemical modifications designed to allow covalent coupling of channel-forming peptide motifs into variable sized oligomers, a series of alamethicin derivatives was prepared. The building block encompassing the N-terminal 1-17 residues of alamethicin behaved normally in the conductance assay on planar lipid bilayers, albeit at higher concentration and with a slightly reduced voltage-dependence. A linker Ac-K-OCH(2)C(6)H(4)CH(3)p attached via the epsilon amino group of lysine to the C-terminus of alamethicin(1-17) increased membrane affinity. The latter was further enhanced in a dimer and a tetramer in which alamethicin(1-17) chains were tethered to di- or tetra-lysine linkers, respectively, but macroscopic current-voltage curves displayed much reduced voltage-dependencies and reversed hysteresis. An usual behaviour with high voltage-dependence was restored with the modified dimer of alamethicin(1-17) in which alanine separated the two consecutive lysine residues in the linker. Of special interest was the development of a 'negative resistance' branch in macroscopic current-voltage curves for low concentrations of this dimer with the more flexible linker. Single channel events displayed only one single open state with fast kinetics and whose conductance matches that of the alamethicin heptamer or octamer.  (+info)

A yeast Golgi E-type ATPase with an unusual membrane topology. (6/201)

E-type ATPases are involved in many biological processes such as modulation of neural cell activity, prevention of intravascular thrombosis, and protein glycosylation. In this study, we show that a gene of Saccharomyces cerevisiae, identified by similarity to that of animal ectoapyrase CD39, codes for a new member of the E-type ATPase family (Apy1p). Overexpression of Apy1p in yeast cells causes an increase in intracellular membrane-bound nucleoside di- and triphosphate hydrolase activity. The activity is highest with ADP as substrate and is stimulated similarly by Ca (2+), Mg(2+), and Mn(2+). The results also indicate that Apy1p is an integral membrane protein located predominantly in the Golgi compartment. Sequence analysis reveals that Apy1p contains one large NH(2)-terminal hydrophilic apyrase domain, one COOH-terminal hydrophilic domain, and two hydrophobic stretches in the central region of the polypeptide. Although no signal sequence is found at the NH(2)-terminal portion of the protein and no NH(2)-terminal cleavage of the protein is observed, demonstrated by the detection of NH(2)-terminal tagged Apy1p, the NH(2)-terminal domain of Apylp is on the luminal side of the Golgi apparatus, and the COOH-terminal hydrophilic domain binds to the cytoplasmic face of the Golgi membrane. The second hydrophobic stretch of Apy1p is the transmembrane domain. These results indicate that Apylp is a type III transmembrane protein; however, the size of the Apy1p extracytoplasmic NH(2) terminus is much larger than those of other type III transmembrane proteins, suggesting that a novel translocation mechanism is utilized.  (+info)

The ion-channel activity of longibrachins LGA I and LGB II: effects of pro-2/Ala and gln-18/Glu substitutions on the alamethicin voltage-gated membrane channels. (7/201)

Longibrachins LGA I (Ac Aib Ala Aib Ala Aib(5) Ala Gln Aib Val Aib(10) Gly Leu Aib Pro Val(15) Aib Aib Gln Gln Pheol(20), with Aib: alpha-aminoisobutyric acid, pheol: phenylalaninol) and LGB II are two homologous 20-residue long-sequence peptaibols isolated from the fungus Trichoderma longibrachiatum that differ between them by a Gln-18/Glu substitution. They distinguish from alamethicin by a Pro-2 for Ala replacement, which allowed to examine for the first time with natural Aib-containing analogues, the effect of Pro-2 on the ion-channel properties exhibited by alamethicin. The influence of these structural modifications on the voltage-gated ion-channel forming activity of the peptides in planar lipid bilayers were analysed. The general 'barrel-stave' model of ion-channel activity, already described for alamethicin, was preserved with both longibrachins. The negatively charged LGB II promoted higher oligomerisation levels, which could presumably dilute the repulsive effect of the negative Glu ring near the entrance of the channel and resulted in lower lifetimes of the substates, confirming the strong anchor of the peptide C-terminus at the cis-interface. Reduction of the channel lifetimes was observed for the longibrachins, compared to alamethicin. This argues for a better stabilisation of the channels formed by peptaibols having a proline at position 2, which results in better anchoring of the peptide monomer N-terminus at the trans-bilayer interface. Qualitative assays of the temperature dependence on the neutral longibrachin channel properties demonstrated a high increase of channel lifetimes and a markedly reduced voltage-sensitivity when the temperature was decreased, showing that such conditions may allow to study the channel-forming properties of peptides leading to fast current fluctuations.  (+info)

Voltage-dependent interaction of the peptaibol antibiotic zervamicin II with phospholipid vesicles. (8/201)

The effect of a transmembrane potential on ion channel formation by zervamicin II (ZER-II) was studied in a vesicular model system. The dissipation of diffusion potential caused by addition of ZER-II to small phosphatidylcholine vesicles was monitored using fluorescent (Safranine T) and optical (Oxonol YI) probes. Cis-positive potentials facilitated channel formation, while at cis-negative potentials, ion fluxes were inhibited. A potential-independent behavior of ZER-II was observed at high peptide concentrations, most likely due to its membrane modifying property.  (+info)

Peptaibols are a class of naturally occurring peptides that are characterized by their unusual structural features. They are typically composed of 5-20 amino acids, with a high proportion of non-polar and alpha-aminoisobutyric acid (Aib) residues. The Aib residue is unique to peptaibols and contributes to their ability to form stable alpha-helices in hydrophobic environments.

Peptaibols are produced by a variety of fungi, including species from the genera Trichoderma, Gliocladium, and Emericella. They have been found to exhibit a range of biological activities, including antimicrobial, insecticidal, and immunomodulatory effects. Some peptaibols have also been shown to disrupt ion channels in cell membranes, which may contribute to their ability to act as ionophores and transport ions across membranes.

Due to their unique structural features and biological activities, peptaibols have attracted interest from researchers in fields such as medicinal chemistry, drug discovery, and biotechnology. However, further research is needed to fully understand their mechanisms of action and potential therapeutic applications.

A lipid bilayer is a thin membrane made up of two layers of lipid molecules, primarily phospholipids. The hydrophilic (water-loving) heads of the lipids face outwards, coming into contact with watery environments on both sides, while the hydrophobic (water-fearing) tails point inward, away from the aqueous surroundings. This unique structure allows lipid bilayers to form a stable barrier that controls the movement of molecules and ions in and out of cells and organelles, thus playing a crucial role in maintaining cellular compartmentalization and homeostasis.

Ion channels are specialized transmembrane proteins that form hydrophilic pores or gaps in the lipid bilayer of cell membranes. They regulate the movement of ions (such as sodium, potassium, calcium, and chloride) across the cell membrane by allowing these charged particles to pass through selectively in response to various stimuli, including voltage changes, ligand binding, mechanical stress, or temperature changes. This ion movement is essential for many physiological processes, including electrical signaling, neurotransmission, muscle contraction, and maintenance of resting membrane potential. Ion channels can be categorized based on their activation mechanisms, ion selectivity, and structural features. Dysfunction of ion channels can lead to various diseases, making them important targets for drug development.

I'm sorry for any confusion, but the term "Melitten" does not appear to be a recognized medical term or condition. It is possible that there may be a spelling mistake or typo in the term you are looking for. Please double-check the spelling and try again, or provide more context so I can try to help you find the information you're looking for.

Ionophores are compounds that have the ability to form complexes with ions and facilitate their transportation across biological membranes. They can be either organic or inorganic molecules, and they play important roles in various physiological processes, including ion homeostasis, signal transduction, and antibiotic activity. In medicine and research, ionophores are used as tools to study ion transport, modulate cellular functions, and as therapeutic agents, especially in the treatment of bacterial and fungal infections.

Niclosamide is an antihelminthic medication, which means it is used to treat infections caused by parasitic worms. It works by disrupting the metabolism of the worms, leading to their elimination from the body. Niclosamide is specifically indicated for the treatment of tapeworm infections (such as Taenia saginata, Taenia solium, and Hymenolepis nana).

It's important to note that niclosamide is not typically absorbed into the human body when taken as directed, so it primarily affects the worms in the digestive tract. However, if you have any specific questions about niclosamide or its use, please consult a healthcare professional for medical advice tailored to your particular circumstances.

Phosphatidylcholines (PtdCho) are a type of phospholipids that are essential components of cell membranes in living organisms. They are composed of a hydrophilic head group, which contains a choline moiety, and two hydrophobic fatty acid chains. Phosphatidylcholines are crucial for maintaining the structural integrity and function of cell membranes, and they also serve as important precursors for the synthesis of signaling molecules such as acetylcholine. They can be found in various tissues and biological fluids, including blood, and are abundant in foods such as soybeans, eggs, and meat. Phosphatidylcholines have been studied for their potential health benefits, including their role in maintaining healthy lipid metabolism and reducing the risk of cardiovascular disease.

Biophysical phenomena refer to the observable events and processes that occur in living organisms, which can be explained and studied using the principles and methods of physics. These phenomena can include a wide range of biological processes at various levels of organization, from molecular interactions to whole-organism behaviors. Examples of biophysical phenomena include the mechanics of muscle contraction, the electrical activity of neurons, the transport of molecules across cell membranes, and the optical properties of biological tissues. By applying physical theories and techniques to the study of living systems, biophysicists seek to better understand the fundamental principles that govern life and to develop new approaches for diagnosing and treating diseases.

I'm sorry for any confusion, but "octanes" is not a medical term. It is a term used in chemistry and physics, particularly in reference to fuel. Octane is a hydrocarbon molecule found in gasoline, and it is used as a measure of the fuel's ability to resist engine knocking or pinging during combustion.

The octane rating of gasoline typically ranges from 87 (regular) to 91-93 (premium). Higher-octane fuels are often recommended for high-performance vehicles that have higher compression ratios in their engines. If you have any questions related to medical terminology, I'd be happy to help!

Biophysics is a interdisciplinary field that combines the principles and methods of physics with those of biology to study biological systems and phenomena. It involves the use of physical theories, models, and techniques to understand and explain the properties, functions, and behaviors of living organisms and their constituents, such as cells, proteins, and DNA.

Biophysics can be applied to various areas of biology, including molecular biology, cell biology, neuroscience, and physiology. It can help elucidate the mechanisms of biological processes at the molecular and cellular levels, such as protein folding, ion transport, enzyme kinetics, gene expression, and signal transduction. Biophysical methods can also be used to develop diagnostic and therapeutic tools for medical applications, such as medical imaging, drug delivery, and gene therapy.

Examples of biophysical techniques include X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, electron microscopy, fluorescence microscopy, atomic force microscopy, and computational modeling. These methods allow researchers to probe the structure, dynamics, and interactions of biological molecules and systems with high precision and resolution, providing insights into their functions and behaviors.

Electric conductivity, also known as electrical conductance, is a measure of a material's ability to allow the flow of electric current through it. It is usually measured in units of Siemens per meter (S/m) or ohm-meters (Ω-m).

In medical terms, electric conductivity can refer to the body's ability to conduct electrical signals, which is important for various physiological processes such as nerve impulse transmission and muscle contraction. Abnormalities in electrical conductivity can be associated with various medical conditions, including neurological disorders and heart diseases.

For example, in electrocardiography (ECG), the electric conductivity of the heart is measured to assess its electrical activity and identify any abnormalities that may indicate heart disease. Similarly, in electromyography (EMG), the electric conductivity of muscles is measured to diagnose neuromuscular disorders.

I'm sorry for any confusion, but Tetrathionic Acid is not a medical term. It is a chemical compound with the formula S4O62-. It's an acidic oxyanion of sulfur with the sulfur in the +5 oxidation state. It is not related to human health or medicine directly. If you have any questions about a medical topic, I'd be happy to help with that instead!

Artificial membranes are synthetic or man-made materials that possess properties similar to natural biological membranes, such as selective permeability and barrier functions. These membranes can be designed to control the movement of molecules, ions, or cells across them, making them useful in various medical and biotechnological applications.

Examples of artificial membranes include:

1. Dialysis membranes: Used in hemodialysis for patients with renal failure, these semi-permeable membranes filter waste products and excess fluids from the blood while retaining essential proteins and cells.
2. Hemofiltration membranes: Utilized in extracorporeal circuits to remove larger molecules, such as cytokines or inflammatory mediators, from the blood during critical illnesses or sepsis.
3. Drug delivery systems: Artificial membranes can be used to encapsulate drugs, allowing for controlled release and targeted drug delivery in specific tissues or cells.
4. Tissue engineering: Synthetic membranes serve as scaffolds for cell growth and tissue regeneration, guiding the formation of new functional tissues.
5. Biosensors: Artificial membranes can be integrated into biosensing devices to selectively detect and quantify biomolecules, such as proteins or nucleic acids, in diagnostic applications.
6. Microfluidics: Artificial membranes are used in microfluidic systems for lab-on-a-chip applications, enabling the manipulation and analysis of small volumes of fluids for various medical and biological purposes.

Trichoderma is a genus of fungi that are commonly found in soil, decaying wood, and other organic matter. While there are many different species of Trichoderma, some of them have been studied for their potential use in various medical and industrial applications. For example, certain Trichoderma species have been shown to have antimicrobial properties and can be used to control plant diseases. Other species are being investigated for their ability to produce enzymes and other compounds that may have industrial or medicinal uses.

However, it's important to note that not all Trichoderma species are beneficial, and some of them can cause infections in humans, particularly in individuals with weakened immune systems. These infections can be difficult to diagnose and treat, as they often involve multiple organ systems and may require aggressive antifungal therapy.

In summary, Trichoderma is a genus of fungi that can have both beneficial and harmful effects on human health, depending on the specific species involved and the context in which they are encountered.

"Spin labels" are a term used in the field of magnetic resonance, including nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR). They refer to molecules or atoms that have been chemically attached to a system of interest and possess a stable, unpaired electron. This unpaired electron behaves like a tiny magnet and can be manipulated using magnetic fields and radiofrequency pulses in EPR experiments. The resulting changes in the electron's spin state can provide information about the local environment, dynamics, and structure of the system to which it is attached. Spin labels are often used in biochemistry and materials science to study complex biological systems or materials at the molecular level.

Electrochemistry is a branch of chemistry that deals with the interconversion of electrical energy and chemical energy. It involves the study of chemical processes that cause electrons to move, resulting in the transfer of electrical charge, and the reverse processes by which electrical energy can be used to drive chemical reactions. This field encompasses various phenomena such as the generation of electricity from chemical sources (as in batteries), the electrolysis of substances, and corrosion. Electrochemical reactions are fundamental to many technologies, including energy storage and conversion, environmental protection, and medical diagnostics.

Anti-bacterial agents, also known as antibiotics, are a type of medication used to treat infections caused by bacteria. These agents work by either killing the bacteria or inhibiting their growth and reproduction. There are several different classes of anti-bacterial agents, including penicillins, cephalosporins, fluoroquinolones, macrolides, and tetracyclines, among others. Each class of antibiotic has a specific mechanism of action and is used to treat certain types of bacterial infections. It's important to note that anti-bacterial agents are not effective against viral infections, such as the common cold or flu. Misuse and overuse of antibiotics can lead to antibiotic resistance, which is a significant global health concern.

Secondary protein structure refers to the local spatial arrangement of amino acid chains in a protein, typically described as regular repeating patterns held together by hydrogen bonds. The two most common types of secondary structures are the alpha-helix (α-helix) and the beta-pleated sheet (β-sheet). In an α-helix, the polypeptide chain twists around itself in a helical shape, with each backbone atom forming a hydrogen bond with the fourth amino acid residue along the chain. This forms a rigid rod-like structure that is resistant to bending or twisting forces. In β-sheets, adjacent segments of the polypeptide chain run parallel or antiparallel to each other and are connected by hydrogen bonds, forming a pleated sheet-like arrangement. These secondary structures provide the foundation for the formation of tertiary and quaternary protein structures, which determine the overall three-dimensional shape and function of the protein.

Molecular models are three-dimensional representations of molecular structures that are used in the field of molecular biology and chemistry to visualize and understand the spatial arrangement of atoms and bonds within a molecule. These models can be physical or computer-generated and allow researchers to study the shape, size, and behavior of molecules, which is crucial for understanding their function and interactions with other molecules.

Physical molecular models are often made up of balls (representing atoms) connected by rods or sticks (representing bonds). These models can be constructed manually using materials such as plastic or wooden balls and rods, or they can be created using 3D printing technology.

Computer-generated molecular models, on the other hand, are created using specialized software that allows researchers to visualize and manipulate molecular structures in three dimensions. These models can be used to simulate molecular interactions, predict molecular behavior, and design new drugs or chemicals with specific properties. Overall, molecular models play a critical role in advancing our understanding of molecular structures and their functions.

Cyclic N-oxides are a class of organic compounds that contain a cyclic structure with a nitrogen atom bonded to an oxygen atom as an N-oxide. An N-oxide is a compound in which the nitrogen atom has a positive charge and the oxygen atom has a negative charge, forming a polar covalent bond. In cyclic N-oxides, this N-O group is part of a ring structure, which can be composed of various combinations of carbon, nitrogen, and other atoms. These compounds have been studied for their potential use in pharmaceuticals, agrochemicals, and materials science.

Phosphatidylethanolamines (PE) are a type of phospholipid that are abundantly found in the cell membranes of living organisms. They play a crucial role in maintaining the structural integrity and functionality of the cell membrane. PE contains a hydrophilic head, which consists of an ethanolamine group linked to a phosphate group, and two hydrophobic fatty acid chains. This unique structure allows PE to form a lipid bilayer, where the hydrophilic heads face outwards and interact with the aqueous environment, while the hydrophobic tails face inwards and interact with each other.

PE is also involved in various cellular processes, such as membrane trafficking, autophagy, and signal transduction. Additionally, PE can be modified by the addition of various functional groups or molecules, which can further regulate its functions and interactions within the cell. Overall, phosphatidylethanolamines are essential components of cellular membranes and play a critical role in maintaining cellular homeostasis.

Membrane potential is the electrical potential difference across a cell membrane, typically for excitable cells such as nerve and muscle cells. It is the difference in electric charge between the inside and outside of a cell, created by the selective permeability of the cell membrane to different ions. The resting membrane potential of a typical animal cell is around -70 mV, with the interior being negative relative to the exterior. This potential is generated and maintained by the active transport of ions across the membrane, primarily through the action of the sodium-potassium pump. Membrane potentials play a crucial role in many physiological processes, including the transmission of nerve impulses and the contraction of muscle cells.

Dimyristoylphosphatidylcholine (DMPC) is a type of phospholipid molecule that is commonly found in animal cell membranes. It is composed of two myristoyl fatty acid chains, a phosphate group, and a choline headgroup. DMPC has a gel-to-liquid crystalline phase transition temperature of around 23-25°C, which makes it a useful compound for studying the physical properties of lipid membranes and for creating model membrane systems in laboratory experiments.

Membrane fluidity, in the context of cell biology, refers to the ability of the phospholipid bilayer that makes up the cell membrane to change its structure and organization in response to various factors. The membrane is not a static structure but rather a dynamic one, with its lipids constantly moving and changing position.

Membrane fluidity is determined by the fatty acid composition of the phospholipids that make up the bilayer. Lipids with unsaturated fatty acids have kinks in their hydrocarbon chains, which prevent them from packing closely together and increase membrane fluidity. In contrast, lipids with saturated fatty acids can pack closely together, reducing membrane fluidity.

Membrane fluidity is important for various cellular processes, including the movement of proteins within the membrane, the fusion of vesicles with the membrane during exocytosis and endocytosis, and the ability of the membrane to respond to changes in temperature and other environmental factors. Abnormalities in membrane fluidity have been linked to various diseases, including cancer, neurological disorders, and infectious diseases.

Glucuronides are conjugated compounds formed in the liver by the attachment of glucuronic acid to a variety of molecules, including drugs, hormones, and environmental toxins. This process, known as glucuronidation, is catalyzed by enzymes called UDP-glucuronosyltransferases (UGTs) and increases the water solubility of these compounds, allowing them to be more easily excreted from the body through urine or bile.

Glucuronidation plays a crucial role in the detoxification and elimination of many substances, including drugs and toxins. However, in some cases, glucuronides can also be hydrolyzed back into their original forms by enzymes called β-glucuronidases, which can lead to reabsorption of the parent compound and prolong its effects or toxicity.

Overall, understanding the metabolism and disposition of glucuronides is important for predicting drug interactions, pharmacokinetics, and potential adverse effects.

Glucuronosyltransferase (UDP-glucuronosyltransferase) is an enzyme belonging to the family of glycosyltransferases. It plays a crucial role in the process of biotransformation and detoxification of various endogenous and exogenous substances, including drugs, hormones, and environmental toxins, in the liver and other organs.

The enzyme functions by transferring a glucuronic acid moiety from a donor molecule, uridine diphosphate glucuronic acid (UDP-GlcUA), to an acceptor molecule, which can be a variety of hydrophobic compounds. This reaction results in the formation of a more water-soluble glucuronide conjugate, facilitating the excretion of the substrate through urine or bile.

There are multiple isoforms of glucuronosyltransferase, classified into two main families: UGT1 and UGT2. These isoforms exhibit different substrate specificities and tissue distributions, allowing for a wide range of compounds to be metabolized through the glucuronidation pathway.

In summary, Glucuronosyltransferase is an essential enzyme in the detoxification process, facilitating the elimination of various substances from the body by conjugating them with a glucuronic acid moiety.

An amino acid sequence is the specific order of amino acids in a protein or peptide molecule, formed by the linking of the amino group (-NH2) of one amino acid to the carboxyl group (-COOH) of another amino acid through a peptide bond. The sequence is determined by the genetic code and is unique to each type of protein or peptide. It plays a crucial role in determining the three-dimensional structure and function of proteins.

Peptides are short chains of amino acid residues linked by covalent bonds, known as peptide bonds. They are formed when two or more amino acids are joined together through a condensation reaction, which results in the elimination of a water molecule and the formation of an amide bond between the carboxyl group of one amino acid and the amino group of another.

Peptides can vary in length from two to about fifty amino acids, and they are often classified based on their size. For example, dipeptides contain two amino acids, tripeptides contain three, and so on. Oligopeptides typically contain up to ten amino acids, while polypeptides can contain dozens or even hundreds of amino acids.

Peptides play many important roles in the body, including serving as hormones, neurotransmitters, enzymes, and antibiotics. They are also used in medical research and therapeutic applications, such as drug delivery and tissue engineering.

Solvents, in a medical context, are substances that are capable of dissolving or dispersing other materials, often used in the preparation of medications and solutions. They are commonly organic chemicals that can liquefy various substances, making it possible to administer them in different forms, such as oral solutions, topical creams, or injectable drugs.

However, it is essential to recognize that solvents may pose health risks if mishandled or misused, particularly when they contain volatile organic compounds (VOCs). Prolonged exposure to these VOCs can lead to adverse health effects, including respiratory issues, neurological damage, and even cancer. Therefore, it is crucial to handle solvents with care and follow safety guidelines to minimize potential health hazards.

Medical definitions of water generally describe it as a colorless, odorless, tasteless liquid that is essential for all forms of life. It is a universal solvent, making it an excellent medium for transporting nutrients and waste products within the body. Water constitutes about 50-70% of an individual's body weight, depending on factors such as age, sex, and muscle mass.

In medical terms, water has several important functions in the human body:

1. Regulation of body temperature through perspiration and respiration.
2. Acting as a lubricant for joints and tissues.
3. Facilitating digestion by helping to break down food particles.
4. Transporting nutrients, oxygen, and waste products throughout the body.
5. Helping to maintain healthy skin and mucous membranes.
6. Assisting in the regulation of various bodily functions, such as blood pressure and heart rate.

Dehydration can occur when an individual does not consume enough water or loses too much fluid due to illness, exercise, or other factors. This can lead to a variety of symptoms, including dry mouth, fatigue, dizziness, and confusion. Severe dehydration can be life-threatening if left untreated.

I'm sorry for any confusion, but there seems to be a misunderstanding. Mathematics is not a medical term; it is a branch of science dedicated to the study of numbers, shapes, and structures. However, mathematics does have many applications in medicine, such as in modeling disease spread, analyzing medical images, or designing clinical trials. If you have any questions related to mathematics in a medical context, I'd be happy to help clarify those for you!

Molecular sequence data refers to the specific arrangement of molecules, most commonly nucleotides in DNA or RNA, or amino acids in proteins, that make up a biological macromolecule. This data is generated through laboratory techniques such as sequencing, and provides information about the exact order of the constituent molecules. This data is crucial in various fields of biology, including genetics, evolution, and molecular biology, allowing for comparisons between different organisms, identification of genetic variations, and studies of gene function and regulation.

Circular dichroism (CD) is a technique used in physics and chemistry to study the structure of molecules, particularly large biological molecules such as proteins and nucleic acids. It measures the difference in absorption of left-handed and right-handed circularly polarized light by a sample. This difference in absorption can provide information about the three-dimensional structure of the molecule, including its chirality or "handedness."

In more technical terms, CD is a form of spectroscopy that measures the differential absorption of left and right circularly polarized light as a function of wavelength. The CD signal is measured in units of millidegrees (mdeg) and can be positive or negative, depending on the type of chromophore and its orientation within the molecule.

CD spectra can provide valuable information about the secondary and tertiary structure of proteins, as well as the conformation of nucleic acids. For example, alpha-helical proteins typically exhibit a strong positive band near 190 nm and two negative bands at around 208 nm and 222 nm, while beta-sheet proteins show a strong positive band near 195 nm and two negative bands at around 217 nm and 175 nm.

CD spectroscopy is a powerful tool for studying the structural changes that occur in biological molecules under different conditions, such as temperature, pH, or the presence of ligands or other molecules. It can also be used to monitor the folding and unfolding of proteins, as well as the binding of drugs or other small molecules to their targets.

Hydrogen bonding is not a medical term per se, but it is a fundamental concept in chemistry and biology that is relevant to the field of medicine. Here's a general definition:

Hydrogen bonding is a type of attractive force between molecules or within a molecule, which occurs when a hydrogen atom is bonded to a highly electronegative atom (like nitrogen, oxygen, or fluorine) and is then attracted to another electronegative atom. This attraction results in the formation of a partially covalent bond known as a "hydrogen bond."

In biological systems, hydrogen bonding plays a crucial role in the structure and function of many biomolecules, such as DNA, proteins, and carbohydrates. For example, the double helix structure of DNA is stabilized by hydrogen bonds between complementary base pairs (adenine-thymine and guanine-cytosine). Similarly, the three-dimensional structure of proteins is maintained by a network of hydrogen bonds that help to determine their function.

In medical contexts, hydrogen bonding can be relevant in understanding drug-receptor interactions, where hydrogen bonds between a drug molecule and its target protein can enhance the binding affinity and specificity of the interaction, leading to more effective therapeutic outcomes.

Magnetic Resonance Spectroscopy (MRS) is a non-invasive diagnostic technique that provides information about the biochemical composition of tissues, including their metabolic state. It is often used in conjunction with Magnetic Resonance Imaging (MRI) to analyze various metabolites within body tissues, such as the brain, heart, liver, and muscles.

During MRS, a strong magnetic field, radio waves, and a computer are used to produce detailed images and data about the concentration of specific metabolites in the targeted tissue or organ. This technique can help detect abnormalities related to energy metabolism, neurotransmitter levels, pH balance, and other biochemical processes, which can be useful for diagnosing and monitoring various medical conditions, including cancer, neurological disorders, and metabolic diseases.

There are different types of MRS, such as Proton (^1^H) MRS, Phosphorus-31 (^31^P) MRS, and Carbon-13 (^13^C) MRS, each focusing on specific elements or metabolites within the body. The choice of MRS technique depends on the clinical question being addressed and the type of information needed for diagnosis or monitoring purposes.

X-ray diffraction (XRD) is not strictly a medical definition, but it is a technique commonly used in the field of medical research and diagnostics. XRD is a form of analytical spectroscopy that uses the phenomenon of X-ray diffraction to investigate the crystallographic structure of materials. When a beam of X-rays strikes a crystal, it is scattered in specific directions and with specific intensities that are determined by the arrangement of atoms within the crystal. By measuring these diffraction patterns, researchers can determine the crystal structures of various materials, including biological macromolecules such as proteins and viruses.

In the medical field, XRD is often used to study the structure of drugs and drug candidates, as well as to analyze the composition and structure of tissues and other biological samples. For example, XRD can be used to investigate the crystal structures of calcium phosphate minerals in bone tissue, which can provide insights into the mechanisms of bone formation and disease. Additionally, XRD is sometimes used in the development of new medical imaging techniques, such as phase-contrast X-ray imaging, which has the potential to improve the resolution and contrast of traditional X-ray images.

Alamethicin is a polypeptide antibiotic that is produced by the fungus Trichoderma viride. It is primarily used in research to create artificial ion channels in synthetic lipid bilayers, which allows scientists to study the electrical properties of membranes and the transport of ions across them. Alamethicin is not used as a therapeutic drug in humans or animals.

Structural models in medicine and biology are theoretical or physical representations used to explain the arrangement, organization, and relationship of various components or parts of a living organism or its systems. These models can be conceptual, graphical, mathematical, or computational and are used to understand complex biological structures and processes, such as molecular interactions, cell signaling pathways, organ system functions, and whole-body physiology. Structural models help researchers and healthcare professionals form hypotheses, design experiments, interpret data, and develop interventions for various medical conditions and diseases.

Protein conformation refers to the specific three-dimensional shape that a protein molecule assumes due to the spatial arrangement of its constituent amino acid residues and their associated chemical groups. This complex structure is determined by several factors, including covalent bonds (disulfide bridges), hydrogen bonds, van der Waals forces, and ionic bonds, which help stabilize the protein's unique conformation.

Protein conformations can be broadly classified into two categories: primary, secondary, tertiary, and quaternary structures. The primary structure represents the linear sequence of amino acids in a polypeptide chain. The secondary structure arises from local interactions between adjacent amino acid residues, leading to the formation of recurring motifs such as α-helices and β-sheets. Tertiary structure refers to the overall three-dimensional folding pattern of a single polypeptide chain, while quaternary structure describes the spatial arrangement of multiple folded polypeptide chains (subunits) that interact to form a functional protein complex.

Understanding protein conformation is crucial for elucidating protein function, as the specific three-dimensional shape of a protein directly influences its ability to interact with other molecules, such as ligands, nucleic acids, or other proteins. Any alterations in protein conformation due to genetic mutations, environmental factors, or chemical modifications can lead to loss of function, misfolding, aggregation, and disease states like neurodegenerative disorders and cancer.

Electron Spin Resonance (ESR) Spectroscopy, also known as Electron Paramagnetic Resonance (EPR) Spectroscopy, is a technique used to investigate materials with unpaired electrons. It is based on the principle of absorption of energy by the unpaired electrons when they are exposed to an external magnetic field and microwave radiation.

In this technique, a sample is placed in a magnetic field and microwave radiation is applied. The unpaired electrons in the sample absorb energy and change their spin state when the energy of the microwaves matches the energy difference between the spin states. This absorption of energy is recorded as a function of the magnetic field strength, producing an ESR spectrum.

ESR spectroscopy can provide information about the number, type, and behavior of unpaired electrons in a sample, as well as the local environment around the electron. It is widely used in physics, chemistry, and biology to study materials such as free radicals, transition metal ions, and defects in solids.

Biological models, also known as physiological models or organismal models, are simplified representations of biological systems, processes, or mechanisms that are used to understand and explain the underlying principles and relationships. These models can be theoretical (conceptual or mathematical) or physical (such as anatomical models, cell cultures, or animal models). They are widely used in biomedical research to study various phenomena, including disease pathophysiology, drug action, and therapeutic interventions.

Examples of biological models include:

1. Mathematical models: These use mathematical equations and formulas to describe complex biological systems or processes, such as population dynamics, metabolic pathways, or gene regulation networks. They can help predict the behavior of these systems under different conditions and test hypotheses about their underlying mechanisms.
2. Cell cultures: These are collections of cells grown in a controlled environment, typically in a laboratory dish or flask. They can be used to study cellular processes, such as signal transduction, gene expression, or metabolism, and to test the effects of drugs or other treatments on these processes.
3. Animal models: These are living organisms, usually vertebrates like mice, rats, or non-human primates, that are used to study various aspects of human biology and disease. They can provide valuable insights into the pathophysiology of diseases, the mechanisms of drug action, and the safety and efficacy of new therapies.
4. Anatomical models: These are physical representations of biological structures or systems, such as plastic models of organs or tissues, that can be used for educational purposes or to plan surgical procedures. They can also serve as a basis for developing more sophisticated models, such as computer simulations or 3D-printed replicas.

Overall, biological models play a crucial role in advancing our understanding of biology and medicine, helping to identify new targets for therapeutic intervention, develop novel drugs and treatments, and improve human health.

Molecular conformation, also known as spatial arrangement or configuration, refers to the specific three-dimensional shape and orientation of atoms that make up a molecule. It describes the precise manner in which bonds between atoms are arranged around a molecular framework, taking into account factors such as bond lengths, bond angles, and torsional angles.

Conformational isomers, or conformers, are different spatial arrangements of the same molecule that can interconvert without breaking chemical bonds. These isomers may have varying energies, stability, and reactivity, which can significantly impact a molecule's biological activity and function. Understanding molecular conformation is crucial in fields such as drug design, where small changes in conformation can lead to substantial differences in how a drug interacts with its target.

I'm sorry for any confusion, but "thermodynamics" is not a term that has a specific medical definition. It is a branch of physics that deals with the relationships between heat and other forms of energy. However, the principles of thermodynamics can be applied to biological systems, including those in the human body, such as in the study of metabolism or muscle function. But in a medical context, "thermodynamics" would not be a term used independently as a diagnosis, treatment, or any medical condition.

Liposomes are artificially prepared, small, spherical vesicles composed of one or more lipid bilayers that enclose an aqueous compartment. They can encapsulate both hydrophilic and hydrophobic drugs, making them useful for drug delivery applications in the medical field. The lipid bilayer structure of liposomes is similar to that of biological membranes, which allows them to merge with and deliver their contents into cells. This property makes liposomes a valuable tool in delivering drugs directly to targeted sites within the body, improving drug efficacy while minimizing side effects.

A computer simulation is a process that involves creating a model of a real-world system or phenomenon on a computer and then using that model to run experiments and make predictions about how the system will behave under different conditions. In the medical field, computer simulations are used for a variety of purposes, including:

1. Training and education: Computer simulations can be used to create realistic virtual environments where medical students and professionals can practice their skills and learn new procedures without risk to actual patients. For example, surgeons may use simulation software to practice complex surgical techniques before performing them on real patients.
2. Research and development: Computer simulations can help medical researchers study the behavior of biological systems at a level of detail that would be difficult or impossible to achieve through experimental methods alone. By creating detailed models of cells, tissues, organs, or even entire organisms, researchers can use simulation software to explore how these systems function and how they respond to different stimuli.
3. Drug discovery and development: Computer simulations are an essential tool in modern drug discovery and development. By modeling the behavior of drugs at a molecular level, researchers can predict how they will interact with their targets in the body and identify potential side effects or toxicities. This information can help guide the design of new drugs and reduce the need for expensive and time-consuming clinical trials.
4. Personalized medicine: Computer simulations can be used to create personalized models of individual patients based on their unique genetic, physiological, and environmental characteristics. These models can then be used to predict how a patient will respond to different treatments and identify the most effective therapy for their specific condition.

Overall, computer simulations are a powerful tool in modern medicine, enabling researchers and clinicians to study complex systems and make predictions about how they will behave under a wide range of conditions. By providing insights into the behavior of biological systems at a level of detail that would be difficult or impossible to achieve through experimental methods alone, computer simulations are helping to advance our understanding of human health and disease.

I'm sorry for any confusion, but static electricity is not a term that has a specific medical definition. Static electricity is an electrical charge that builds up on the surface of objects. This occurs when there is an imbalance of electric charges within or on the surface of a material. It can be caused by certain conditions, such as friction, which can build up an electric charge.

While not a medical term, static electricity can have various effects in different settings, including medical ones. For instance, it can cause issues with electronic equipment used in healthcare settings. Additionally, some people may experience a shock or spark when they touch a conductive object that has been charged with static electricity. However, these occurrences are not typically considered medical conditions or issues.

"Physicochemical phenomena" is not a term that has a specific medical definition. However, in general terms, physicochemical phenomena refer to the physical and chemical interactions and processes that occur within living organisms or biological systems. These phenomena can include various properties and reactions such as pH levels, osmotic pressure, enzyme kinetics, and thermodynamics, among others.

In a broader context, physicochemical phenomena play an essential role in understanding the mechanisms of drug action, pharmacokinetics, and toxicity. For instance, the solubility, permeability, and stability of drugs are all physicochemical properties that can affect their absorption, distribution, metabolism, and excretion (ADME) within the body.

Therefore, while not a medical definition per se, an understanding of physicochemical phenomena is crucial to the study and practice of pharmacology, toxicology, and other related medical fields.

A chemical model is a simplified representation or description of a chemical system, based on the laws of chemistry and physics. It is used to explain and predict the behavior of chemicals and chemical reactions. Chemical models can take many forms, including mathematical equations, diagrams, and computer simulations. They are often used in research, education, and industry to understand complex chemical processes and develop new products and technologies.

For example, a chemical model might be used to describe the way that atoms and molecules interact in a particular reaction, or to predict the properties of a new material. Chemical models can also be used to study the behavior of chemicals at the molecular level, such as how they bind to each other or how they are affected by changes in temperature or pressure.

It is important to note that chemical models are simplifications of reality and may not always accurately represent every aspect of a chemical system. They should be used with caution and validated against experimental data whenever possible.

Physical chemistry is a branch of chemistry that deals with the fundamental principles and laws governing the behavior of matter and energy at the molecular and atomic levels. It combines elements of physics, chemistry, mathematics, and engineering to study the properties, composition, structure, and transformation of matter. Key areas of focus in physical chemistry include thermodynamics, kinetics, quantum mechanics, statistical mechanics, electrochemistry, and spectroscopy.

In essence, physical chemists aim to understand how and why chemical reactions occur, what drives them, and how they can be controlled or predicted. This knowledge is crucial for developing new materials, medicines, energy technologies, and other applications that benefit society.

In the context of medicine and pharmacology, "kinetics" refers to the study of how a drug moves throughout the body, including its absorption, distribution, metabolism, and excretion (often abbreviated as ADME). This field is called "pharmacokinetics."

1. Absorption: This is the process of a drug moving from its site of administration into the bloodstream. Factors such as the route of administration (e.g., oral, intravenous, etc.), formulation, and individual physiological differences can affect absorption.

2. Distribution: Once a drug is in the bloodstream, it gets distributed throughout the body to various tissues and organs. This process is influenced by factors like blood flow, protein binding, and lipid solubility of the drug.

3. Metabolism: Drugs are often chemically modified in the body, typically in the liver, through processes known as metabolism. These changes can lead to the formation of active or inactive metabolites, which may then be further distributed, excreted, or undergo additional metabolic transformations.

4. Excretion: This is the process by which drugs and their metabolites are eliminated from the body, primarily through the kidneys (urine) and the liver (bile).

Understanding the kinetics of a drug is crucial for determining its optimal dosing regimen, potential interactions with other medications or foods, and any necessary adjustments for special populations like pediatric or geriatric patients, or those with impaired renal or hepatic function.

Phospholipids are a major class of lipids that consist of a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails. The head is composed of a phosphate group, which is often bound to an organic molecule such as choline, ethanolamine, serine or inositol. The tails are made up of two fatty acid chains.

Phospholipids are a key component of cell membranes and play a crucial role in maintaining the structural integrity and function of the cell. They form a lipid bilayer, with the hydrophilic heads facing outwards and the hydrophobic tails facing inwards, creating a barrier that separates the interior of the cell from the outside environment.

Phospholipids are also involved in various cellular processes such as signal transduction, intracellular trafficking, and protein function regulation. Additionally, they serve as emulsifiers in the digestive system, helping to break down fats in the diet.

Gramicidin is not a medical condition but rather an antibiotic substance that is used in medical treatments.

Here's the scientific and pharmacological definition:

Gramicidin is a narrow-spectrum, cationic antimicrobial peptide derived from gram-positive bacteria of the genus Bacillus. It is an ionophore that selectively binds to monovalent cations, forming channels in lipid bilayers and causing disruption of bacterial cell membranes, leading to bacterial lysis and death. Gramicidin D, a mixture of at least four different gramicidins (A, B, C, and D), is commonly used in topical formulations for the treatment of skin and eye infections due to its potent antimicrobial activity against many gram-positive and some gram-negative bacteria. However, it has limited systemic use due to its potential toxicity to mammalian cells.

Methanol, also known as methyl alcohol or wood alcohol, is a volatile, colorless, flammable liquid with a distinctive odor similar to that of ethanol (drinking alcohol). It is used in various industrial applications such as the production of formaldehyde, acetic acid, and other chemicals. In the medical field, methanol is considered a toxic alcohol that can cause severe intoxication and metabolic disturbances when ingested or improperly consumed. Methanol poisoning can lead to neurological symptoms, blindness, and even death if not treated promptly and effectively.

Potentiometry is a method used in analytical chemistry to measure the potential (or voltage) difference between two electrodes, which reflects the concentration of an ion or a particular molecule in a solution. It involves setting up an electrochemical cell with two electrodes: a working electrode and a reference electrode. The working electrode is immersed in the test solution and its potential is measured against the stable potential of the reference electrode.

The Nernst equation can be used to relate the potential difference to the concentration of the analyte, allowing for quantitative analysis. Potentiometry is often used to measure the activity or concentration of ions such as H+, Na+, K+, and Cl-, as well as other redox-active species.

In medical testing, potentiometry can be used to measure the concentration of certain ions in biological fluids such as blood, urine, or sweat. For example, it can be used to measure the pH of a solution (the concentration of H+ ions) or the concentration of glucose in blood using a glucometer.

Molecular probes, also known as bioprobes or molecular tracers, are molecules that are used to detect and visualize specific biological targets or processes within cells, tissues, or organisms. These probes can be labeled with a variety of detection methods such as fluorescence, radioactivity, or enzymatic activity. They can bind to specific biomolecules such as DNA, RNA, proteins, or lipids and are used in various fields including molecular biology, cell biology, diagnostic medicine, and medical research.

For example, a fluorescent molecular probe may be designed to bind specifically to a certain protein in a living cell. When the probe binds to its target, it emits a detectable signal that can be observed under a microscope, allowing researchers to track the location and behavior of the protein within the cell.

Molecular probes are valuable tools for understanding biological systems at the molecular level, enabling researchers to study complex processes such as gene expression, signal transduction, and metabolism in real-time. They can also be used in clinical settings for diagnostic purposes, such as detecting specific biomarkers of disease or monitoring the effectiveness of therapies.

An ion is an atom or molecule that has gained or lost one or more electrons, resulting in a net electric charge. Cations are positively charged ions, which have lost electrons, while anions are negatively charged ions, which have gained electrons. Ions can play a significant role in various physiological processes within the human body, including enzyme function, nerve impulse transmission, and maintenance of acid-base balance. They also contribute to the formation of salts and buffer systems that help regulate fluid composition and pH levels in different bodily fluids.

Membrane lipids are the main component of biological membranes, forming a lipid bilayer in which various cellular processes take place. These lipids include phospholipids, glycolipids, and cholesterol. Phospholipids are the most abundant type, consisting of a hydrophilic head (containing a phosphate group) and two hydrophobic tails (composed of fatty acid chains). Glycolipids contain a sugar group attached to the lipid molecule. Cholesterol helps regulate membrane fluidity and permeability. Together, these lipids create a selectively permeable barrier that separates cells from their environment and organelles within cells.

Molecular structure, in the context of biochemistry and molecular biology, refers to the arrangement and organization of atoms and chemical bonds within a molecule. It describes the three-dimensional layout of the constituent elements, including their spatial relationships, bond lengths, and angles. Understanding molecular structure is crucial for elucidating the functions and reactivities of biological macromolecules such as proteins, nucleic acids, lipids, and carbohydrates. Various experimental techniques, like X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, and cryo-electron microscopy (cryo-EM), are employed to determine molecular structures at atomic resolution, providing valuable insights into their biological roles and potential therapeutic targets.

Proline is an organic compound that is classified as a non-essential amino acid, meaning it can be produced by the human body and does not need to be obtained through the diet. It is encoded in the genetic code as the codon CCU, CCC, CCA, or CCG. Proline is a cyclic amino acid, containing an unusual secondary amine group, which forms a ring structure with its carboxyl group.

In proteins, proline acts as a structural helix breaker, disrupting the alpha-helix structure and leading to the formation of turns and bends in the protein chain. This property is important for the proper folding and function of many proteins. Proline also plays a role in the stability of collagen, a major structural protein found in connective tissues such as tendons, ligaments, and skin.

In addition to its role in protein structure, proline has been implicated in various cellular processes, including signal transduction, apoptosis, and oxidative stress response. It is also a precursor for the synthesis of other biologically important compounds such as hydroxyproline, which is found in collagen and elastin, and glutamate, an excitatory neurotransmitter in the brain.

Drug stability refers to the ability of a pharmaceutical drug product to maintain its physical, chemical, and biological properties during storage and use, under specified conditions. A stable drug product retains its desired quality, purity, strength, and performance throughout its shelf life. Factors that can affect drug stability include temperature, humidity, light exposure, and container compatibility. Maintaining drug stability is crucial to ensure the safety and efficacy of medications for patients.

Antimicrobial cationic peptides (ACPs) are a group of small, naturally occurring peptides that possess broad-spectrum antimicrobial activity against various microorganisms, including bacteria, fungi, viruses, and parasites. They are called "cationic" because they contain positively charged amino acid residues (such as lysine and arginine), which allow them to interact with and disrupt the negatively charged membranes of microbial cells.

ACPs are produced by a wide range of organisms, including humans, animals, and plants, as part of their innate immune response to infection. They play an important role in protecting the host from invading pathogens by directly killing them or inhibiting their growth.

The antimicrobial activity of ACPs is thought to be mediated by their ability to disrupt the membranes of microbial cells, leading to leakage of cellular contents and death. Some ACPs may also have intracellular targets, such as DNA or protein synthesis, that contribute to their antimicrobial activity.

ACPs are being studied for their potential use as therapeutic agents to treat infectious diseases, particularly those caused by drug-resistant bacteria. However, their clinical application is still in the early stages of development due to concerns about their potential toxicity to host cells and the emergence of resistance mechanisms in microbial pathogens.

In the context of medicine and physiology, permeability refers to the ability of a tissue or membrane to allow the passage of fluids, solutes, or gases. It is often used to describe the property of the capillary walls, which control the exchange of substances between the blood and the surrounding tissues.

The permeability of a membrane can be influenced by various factors, including its molecular structure, charge, and the size of the molecules attempting to pass through it. A more permeable membrane allows for easier passage of substances, while a less permeable membrane restricts the movement of substances.

In some cases, changes in permeability can have significant consequences for health. For example, increased permeability of the blood-brain barrier (a specialized type of capillary that regulates the passage of substances into the brain) has been implicated in a number of neurological conditions, including multiple sclerosis, Alzheimer's disease, and traumatic brain injury.

A cell membrane, also known as the plasma membrane, is a thin semi-permeable phospholipid bilayer that surrounds all cells in animals, plants, and microorganisms. It functions as a barrier to control the movement of substances in and out of the cell, allowing necessary molecules such as nutrients, oxygen, and signaling molecules to enter while keeping out harmful substances and waste products. The cell membrane is composed mainly of phospholipids, which have hydrophilic (water-loving) heads and hydrophobic (water-fearing) tails. This unique structure allows the membrane to be flexible and fluid, yet selectively permeable. Additionally, various proteins are embedded in the membrane that serve as channels, pumps, receptors, and enzymes, contributing to the cell's overall functionality and communication with its environment.

An amide is a functional group or a compound that contains a carbonyl group (a double-bonded carbon atom) and a nitrogen atom. The nitrogen atom is connected to the carbonyl carbon atom by a single bond, and it also has a lone pair of electrons. Amides are commonly found in proteins and peptides, where they form amide bonds (also known as peptide bonds) between individual amino acids.

The general structure of an amide is R-CO-NHR', where R and R' can be alkyl or aryl groups. Amides can be classified into several types based on the nature of R and R' substituents:

* Primary amides: R-CO-NH2
* Secondary amides: R-CO-NHR'
* Tertiary amides: R-CO-NR''R'''

Amides have several important chemical properties. They are generally stable and resistant to hydrolysis under neutral or basic conditions, but they can be hydrolyzed under acidic conditions or with strong bases. Amides also exhibit a characteristic infrared absorption band around 1650 cm-1 due to the carbonyl stretching vibration.

In addition to their prevalence in proteins and peptides, amides are also found in many natural and synthetic compounds, including pharmaceuticals, dyes, and polymers. They have a wide range of applications in chemistry, biology, and materials science.

Radiation scattering is a physical process in which radiation particles or waves deviate from their original direction due to interaction with matter. This phenomenon can occur through various mechanisms such as:

1. Elastic Scattering: Also known as Thomson scattering or Rayleigh scattering, it occurs when the energy of the scattered particle or wave remains unchanged after the collision. In the case of electromagnetic radiation (e.g., light), this results in a change of direction without any loss of energy.
2. Inelastic Scattering: This type of scattering involves an exchange of energy between the scattered particle and the target medium, leading to a change in both direction and energy of the scattered particle or wave. An example is Compton scattering, where high-energy photons (e.g., X-rays or gamma rays) interact with charged particles (usually electrons), resulting in a decrease in photon energy and an increase in electron kinetic energy.
3. Coherent Scattering: In this process, the scattered radiation maintains its phase relationship with the incident radiation, leading to constructive and destructive interference patterns. An example is Bragg scattering, which occurs when X-rays interact with a crystal lattice, resulting in diffraction patterns that reveal information about the crystal structure.

In medical contexts, radiation scattering can have both beneficial and harmful effects. For instance, in diagnostic imaging techniques like computed tomography (CT) scans, radiation scattering contributes to image noise and reduces contrast resolution. However, in radiation therapy for cancer treatment, controlled scattering of therapeutic radiation beams can help ensure that the tumor receives a uniform dose while minimizing exposure to healthy tissues.

Ion channel gating refers to the process by which ion channels in cell membranes open and close in response to various stimuli, allowing ions such as sodium, potassium, and calcium to flow into or out of the cell. This movement of ions is crucial for many physiological processes, including the generation and transmission of electrical signals in nerve cells, muscle contraction, and the regulation of hormone secretion.

Ion channel gating can be regulated by various factors, including voltage changes across the membrane (voltage-gated channels), ligand binding (ligand-gated channels), mechanical stress (mechanosensitive channels), or other intracellular signals (second messenger-gated channels). The opening and closing of ion channels are highly regulated and coordinated processes that play a critical role in maintaining the proper functioning of cells and organ systems.

Fourier Transform Infrared (FTIR) spectroscopy is a type of infrared spectroscopy that uses the Fourier transform mathematical technique to convert the raw data obtained from an interferometer into a more interpretable spectrum. This technique allows for the simultaneous collection of a wide range of wavelengths, resulting in increased sensitivity and speed compared to traditional dispersive infrared spectroscopy.

FTIR spectroscopy measures the absorption or transmission of infrared radiation by a sample as a function of frequency, providing information about the vibrational modes of the molecules present in the sample. This can be used for identification and quantification of chemical compounds, analysis of molecular structure, and investigation of chemical interactions and reactions.

In summary, FTIR spectroscopy is a powerful analytical technique that uses infrared radiation to study the vibrational properties of molecules, with increased sensitivity and speed due to the use of Fourier transform mathematical techniques and an interferometer.

I'm sorry for any confusion, but "Hydrogen" is not a medical term. It is a chemical element with the symbol H and atomic number 1. It is the lightest and most abundant chemical element in the universe, making up about 75% of its elemental mass.

In a medical context, hydrogen can be discussed in terms of molecular hydrogen (H2) which has been studied for potential therapeutic benefits. Some research explores its use as an antioxidant and anti-inflammatory agent, but more studies are needed to confirm these effects and understand the mechanisms behind them.

Microsomes, liver refers to a subcellular fraction of liver cells (hepatocytes) that are obtained during tissue homogenization and subsequent centrifugation. These microsomal fractions are rich in membranous structures known as the endoplasmic reticulum (ER), particularly the rough ER. They are involved in various important cellular processes, most notably the metabolism of xenobiotics (foreign substances) including drugs, toxins, and carcinogens.

The liver microsomes contain a variety of enzymes, such as cytochrome P450 monooxygenases, that are crucial for phase I drug metabolism. These enzymes help in the oxidation, reduction, or hydrolysis of xenobiotics, making them more water-soluble and facilitating their excretion from the body. Additionally, liver microsomes also host other enzymes involved in phase II conjugation reactions, where the metabolites from phase I are further modified by adding polar molecules like glucuronic acid, sulfate, or acetyl groups.

In summary, liver microsomes are a subcellular fraction of liver cells that play a significant role in the metabolism and detoxification of xenobiotics, contributing to the overall protection and maintenance of cellular homeostasis within the body.

Phosphatidylserines are a type of phospholipids that are essential components of the cell membrane, particularly in the brain. They play a crucial role in maintaining the fluidity and permeability of the cell membrane, and are involved in various cellular processes such as signal transduction, protein anchorage, and apoptosis (programmed cell death). Phosphatidylserines contain a polar head group made up of serine amino acids and two non-polar fatty acid tails. They are abundant in the inner layer of the cell membrane but can be externalized to the outer layer during apoptosis, where they serve as signals for recognition and removal of dying cells by the immune system. Phosphatidylserines have been studied for their potential benefits in various medical conditions, including cognitive decline, Alzheimer's disease, and depression.

Deuterium is a stable and non-radioactive isotope of hydrogen. The atomic nucleus of deuterium, called a deuteron, contains one proton and one neutron, giving it an atomic weight of approximately 2.014 atomic mass units (amu). It is also known as heavy hydrogen or heavy water because its hydrogen atoms contain one neutron in addition to the usual one proton found in common hydrogen atoms.

Deuterium occurs naturally in trace amounts in water and other organic compounds, typically making up about 0.015% to 0.018% of all hydrogen atoms. It can be separated from regular hydrogen through various methods such as electrolysis or distillation, and it has many applications in scientific research, particularly in the fields of chemistry and physics.

In medical contexts, deuterium is sometimes used as a tracer to study metabolic processes in the body. By replacing hydrogen atoms in specific molecules with deuterium atoms, researchers can track the movement and transformation of those molecules within living organisms. This technique has been used to investigate various physiological processes, including drug metabolism, energy production, and lipid synthesis.

Cell membrane permeability refers to the ability of various substances, such as molecules and ions, to pass through the cell membrane. The cell membrane, also known as the plasma membrane, is a thin, flexible barrier that surrounds all cells, controlling what enters and leaves the cell. Its primary function is to protect the cell's internal environment and maintain homeostasis.

The permeability of the cell membrane depends on its structure, which consists of a phospholipid bilayer interspersed with proteins. The hydrophilic (water-loving) heads of the phospholipids face outward, while the hydrophobic (water-fearing) tails face inward, creating a barrier that is generally impermeable to large, polar, or charged molecules.

However, specific proteins within the membrane, called channels and transporters, allow certain substances to cross the membrane. Channels are protein structures that span the membrane and provide a pore for ions or small uncharged molecules to pass through. Transporters, on the other hand, are proteins that bind to specific molecules and facilitate their movement across the membrane, often using energy in the form of ATP.

The permeability of the cell membrane can be influenced by various factors, such as temperature, pH, and the presence of certain chemicals or drugs. Changes in permeability can have significant consequences for the cell's function and survival, as they can disrupt ion balances, nutrient uptake, waste removal, and signal transduction.

In medical terms, pressure is defined as the force applied per unit area on an object or body surface. It is often measured in millimeters of mercury (mmHg) in clinical settings. For example, blood pressure is the force exerted by circulating blood on the walls of the arteries and is recorded as two numbers: systolic pressure (when the heart beats and pushes blood out) and diastolic pressure (when the heart rests between beats).

Pressure can also refer to the pressure exerted on a wound or incision to help control bleeding, or the pressure inside the skull or spinal canal. High or low pressure in different body systems can indicate various medical conditions and require appropriate treatment.

Temperature, in a medical context, is a measure of the degree of hotness or coldness of a body or environment. It is usually measured using a thermometer and reported in degrees Celsius (°C), degrees Fahrenheit (°F), or kelvin (K). In the human body, normal core temperature ranges from about 36.5-37.5°C (97.7-99.5°F) when measured rectally, and can vary slightly depending on factors such as time of day, physical activity, and menstrual cycle. Elevated body temperature is a common sign of infection or inflammation, while abnormally low body temperature can indicate hypothermia or other medical conditions.

Nuclear Magnetic Resonance (NMR) Biomolecular is a research technique that uses magnetic fields and radio waves to study the structure and dynamics of biological molecules, such as proteins and nucleic acids. This technique measures the magnetic properties of atomic nuclei within these molecules, specifically their spin, which can be influenced by the application of an external magnetic field.

When a sample is placed in a strong magnetic field, the nuclei absorb and emit electromagnetic radiation at specific frequencies, known as resonance frequencies, which are determined by the molecular structure and environment of the nuclei. By analyzing these resonance frequencies and their interactions, researchers can obtain detailed information about the three-dimensional structure, dynamics, and interactions of biomolecules.

NMR spectroscopy is a non-destructive technique that allows for the study of biological molecules in solution, which makes it an important tool for understanding the function and behavior of these molecules in their natural environment. Additionally, NMR can be used to study the effects of drugs, ligands, and other small molecules on biomolecular structure and dynamics, making it a valuable tool in drug discovery and development.

Crystallization is a process in which a substance transitions from a liquid or dissolved state to a solid state, forming a crystal lattice. In the medical context, crystallization can refer to the formation of crystals within the body, which can occur under certain conditions such as changes in pH, temperature, or concentration of solutes. These crystals can deposit in various tissues and organs, leading to the formation of crystal-induced diseases or disorders.

For example, in patients with gout, uric acid crystals can accumulate in joints, causing inflammation, pain, and swelling. Similarly, in nephrolithiasis (kidney stones), minerals in the urine can crystallize and form stones that can obstruct the urinary tract. Crystallization can also occur in other medical contexts, such as in the formation of dental calculus or plaque, and in the development of cataracts in the eye.

A Structure-Activity Relationship (SAR) in the context of medicinal chemistry and pharmacology refers to the relationship between the chemical structure of a drug or molecule and its biological activity or effect on a target protein, cell, or organism. SAR studies aim to identify patterns and correlations between structural features of a compound and its ability to interact with a specific biological target, leading to a desired therapeutic response or undesired side effects.

By analyzing the SAR, researchers can optimize the chemical structure of lead compounds to enhance their potency, selectivity, safety, and pharmacokinetic properties, ultimately guiding the design and development of novel drugs with improved efficacy and reduced toxicity.

Membrane proteins are a type of protein that are embedded in the lipid bilayer of biological membranes, such as the plasma membrane of cells or the inner membrane of mitochondria. These proteins play crucial roles in various cellular processes, including:

1. Cell-cell recognition and signaling
2. Transport of molecules across the membrane (selective permeability)
3. Enzymatic reactions at the membrane surface
4. Energy transduction and conversion
5. Mechanosensation and signal transduction

Membrane proteins can be classified into two main categories: integral membrane proteins, which are permanently associated with the lipid bilayer, and peripheral membrane proteins, which are temporarily or loosely attached to the membrane surface. Integral membrane proteins can further be divided into three subcategories based on their topology:

1. Transmembrane proteins, which span the entire width of the lipid bilayer with one or more alpha-helices or beta-barrels.
2. Lipid-anchored proteins, which are covalently attached to lipids in the membrane via a glycosylphosphatidylinositol (GPI) anchor or other lipid modifications.
3. Monotopic proteins, which are partially embedded in the membrane and have one or more domains exposed to either side of the bilayer.

Membrane proteins are essential for maintaining cellular homeostasis and are targets for various therapeutic interventions, including drug development and gene therapy. However, their structural complexity and hydrophobicity make them challenging to study using traditional biochemical methods, requiring specialized techniques such as X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, and single-particle cryo-electron microscopy (cryo-EM).

Hydrogen-ion concentration, also known as pH, is a measure of the acidity or basicity of a solution. It is defined as the negative logarithm (to the base 10) of the hydrogen ion activity in a solution. The standard unit of measurement is the pH unit. A pH of 7 is neutral, less than 7 is acidic, and greater than 7 is basic.

In medical terms, hydrogen-ion concentration is important for maintaining homeostasis within the body. For example, in the stomach, a high hydrogen-ion concentration (low pH) is necessary for the digestion of food. However, in other parts of the body such as blood, a high hydrogen-ion concentration can be harmful and lead to acidosis. Conversely, a low hydrogen-ion concentration (high pH) in the blood can lead to alkalosis. Both acidosis and alkalosis can have serious consequences on various organ systems if not corrected.

In the field of medicine, "time factors" refer to the duration of symptoms or time elapsed since the onset of a medical condition, which can have significant implications for diagnosis and treatment. Understanding time factors is crucial in determining the progression of a disease, evaluating the effectiveness of treatments, and making critical decisions regarding patient care.

For example, in stroke management, "time is brain," meaning that rapid intervention within a specific time frame (usually within 4.5 hours) is essential to administering tissue plasminogen activator (tPA), a clot-busting drug that can minimize brain damage and improve patient outcomes. Similarly, in trauma care, the "golden hour" concept emphasizes the importance of providing definitive care within the first 60 minutes after injury to increase survival rates and reduce morbidity.

Time factors also play a role in monitoring the progression of chronic conditions like diabetes or heart disease, where regular follow-ups and assessments help determine appropriate treatment adjustments and prevent complications. In infectious diseases, time factors are crucial for initiating antibiotic therapy and identifying potential outbreaks to control their spread.

Overall, "time factors" encompass the significance of recognizing and acting promptly in various medical scenarios to optimize patient outcomes and provide effective care.

Calcium is an essential mineral that is vital for various physiological processes in the human body. The medical definition of calcium is as follows:

Calcium (Ca2+) is a crucial cation and the most abundant mineral in the human body, with approximately 99% of it found in bones and teeth. It plays a vital role in maintaining structural integrity, nerve impulse transmission, muscle contraction, hormonal secretion, blood coagulation, and enzyme activation.

Calcium homeostasis is tightly regulated through the interplay of several hormones, including parathyroid hormone (PTH), calcitonin, and vitamin D. Dietary calcium intake, absorption, and excretion are also critical factors in maintaining optimal calcium levels in the body.

Hypocalcemia refers to low serum calcium levels, while hypercalcemia indicates high serum calcium levels. Both conditions can have detrimental effects on various organ systems and require medical intervention to correct.

Patch-clamp techniques are a group of electrophysiological methods used to study ion channels and other electrical properties of cells. These techniques were developed by Erwin Neher and Bert Sakmann, who were awarded the Nobel Prize in Physiology or Medicine in 1991 for their work. The basic principle of patch-clamp techniques involves creating a high resistance seal between a glass micropipette and the cell membrane, allowing for the measurement of current flowing through individual ion channels or groups of channels.

There are several different configurations of patch-clamp techniques, including:

1. Cell-attached configuration: In this configuration, the micropipette is attached to the outer surface of the cell membrane, and the current flowing across a single ion channel can be measured. This configuration allows for the study of the properties of individual channels in their native environment.
2. Whole-cell configuration: Here, the micropipette breaks through the cell membrane, creating a low resistance electrical connection between the pipette and the inside of the cell. This configuration allows for the measurement of the total current flowing across all ion channels in the cell membrane.
3. Inside-out configuration: In this configuration, the micropipette is pulled away from the cell after establishing a seal, resulting in the exposure of the inner surface of the cell membrane to the solution in the pipette. This configuration allows for the study of the properties of ion channels in isolation from other cellular components.
4. Outside-out configuration: Here, the micropipette is pulled away from the cell after establishing a seal, resulting in the exposure of the outer surface of the cell membrane to the solution in the pipette. This configuration allows for the study of the properties of ion channels in their native environment, but with the ability to control the composition of the extracellular solution.

Patch-clamp techniques have been instrumental in advancing our understanding of ion channel function and have contributed to numerous breakthroughs in neuroscience, pharmacology, and physiology.

In the context of medical and biological sciences, a "binding site" refers to a specific location on a protein, molecule, or cell where another molecule can attach or bind. This binding interaction can lead to various functional changes in the original protein or molecule. The other molecule that binds to the binding site is often referred to as a ligand, which can be a small molecule, ion, or even another protein.

The binding between a ligand and its target binding site can be specific and selective, meaning that only certain ligands can bind to particular binding sites with high affinity. This specificity plays a crucial role in various biological processes, such as signal transduction, enzyme catalysis, or drug action.

In the case of drug development, understanding the location and properties of binding sites on target proteins is essential for designing drugs that can selectively bind to these sites and modulate protein function. This knowledge can help create more effective and safer therapeutic options for various diseases.

Explore structures of Alamethicin at the protein data bank Alamethicin in Norine From "A voltage-gated ion channel model ... Alamethicin biosynthesis is hypothesized to be catalyzed by alamethicin synthase, a Nonribosomal peptide synthase (NRPS) first ... Alamethicin product page from Fermentek Rindfleisch, H.; Kleinkauf, H. (1976-03-01). "Biosynthesis of alamethicin". FEBS ... Alamethicin is a channel-forming peptide antibiotic, produced by the fungus Trichoderma viride. It belongs to peptaibol ...
The most widely known peptaibol is alamethicin. Chugh JK, Wallace BA (August 2001). "Peptaibols: models for ion channels". ...
"The antibacterial activity of alamethicins and zervamicins". Journal of Applied Bacteriology. 63 (4): 293-298. doi:10.1111/j. ...
Gramicidin and alamethicin had been popular starting points for selective modifications. The above diagram illustrates one ... The latter, demonstrated in natural channels such as alamethicin, is rarely encountered in synthetic ion channels. They may be ... "Alamethicin−Leucine Zipper Hybrid Peptide: A Prototype for the Design of Artificial Receptors and Ion Channels". Journal of the ...
Marsh, Derek; Jost, Micha; Peggion, Cristina; Toniolo, Claudio (2007). "TOAC spin labels in the backbone of alamethicin: EPR ...
Both of these amino acids are found in peptidic lantibiotics such as alamethicin. However, in plants, 1-aminocyclopropane-1- ...
Penicillin, cephalosporins, fusafungine, usnic acid, fusidic acid, fumagillin, brefeldin A, verrucarin A, alamethicin, are ...
Fox, R.O.; Richards, F.M. (1982). "A voltage-gated ion channel model inferred from the crystal structure of alamethicin at 1.5- ... the ion-channel-forming alamethicin (PDB: 1AMT​) (Fox & Richards 1982), and mutants of ribonuclease S (e.g., PDB: 1RBD​;PDB: ...
It is rare in nature, having been only found in meteorites, and some antibiotics of fungal origin, such as alamethicin and some ...
Subsequent discoveries included alamethicin, aphidicolin, brefeldin A, cephalosporin, cerulenin, citromycin, eupenifeldin, ...
Anisomycin, Thiolutin, Wortmannin, K252a, Staurosporine, K252C, Bafilomycin, Alamethicin, Leptomycin, A23187, Chelerythrine, ...
Family 1.D.3 The Channel-Forming Syringopeptin Family 1.D.4 The Tolaasin Channel-forming Family 1.D.5 The Alamethicin or ...
Aequorin Aflatoxin Agar Alamethicin Alanine Albumins Aldosterone Aleurone Alpha-amanitin Alpha-MSH (Melaninocyte stimulating ...
... alamethicin MeSH D04.345.566.050 - amanitins MeSH D04.345.566.075 - bacitracin MeSH D04.345.566.142 - capreomycin sulfate MeSH ...
... alamethicin MeSH D12.644.641.050 - amanitins MeSH D12.644.641.075 - bacitracin MeSH D12.644.641.142 - capreomycin sulfate MeSH ...
Explore structures of Alamethicin at the protein data bank Alamethicin in Norine From "A voltage-gated ion channel model ... Alamethicin biosynthesis is hypothesized to be catalyzed by alamethicin synthase, a Nonribosomal peptide synthase (NRPS) first ... Alamethicin product page from Fermentek Rindfleisch, H.; Kleinkauf, H. (1976-03-01). "Biosynthesis of alamethicin". FEBS ... Alamethicin is a channel-forming peptide antibiotic, produced by the fungus Trichoderma viride. It belongs to peptaibol ...
Alamethicin suppresses methanogenesis and promotes acetogenesis in bioelectrochemical systems. Xiuping Zhu, Michael Siegert, ... Dive into the research topics of Alamethicin suppresses methanogenesis and promotes acetogenesis in bioelectrochemical systems ...
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Alamethicin is a 20-amino acid channel-forming peptide antibiotic isolated from the fungus Trichoderma viride. Alamethicin ... Alamethicin, Ready Made Solution from Trichoderma Viride. Alamethicin is a 20-amino acid channel-forming peptide antibiotic ... Alamethicin consists of several isoforms. Alamethicin is a 20-amino acid channel-forming peptide antibiotic that can function ... Alamethicin has been used to develop methods for the routine assessment of potential new drug candidates to elicit their ...
Alamethicin, Ready Made Solution from Trichoderma viride. Synonym(s). : U-22324. CAS No.. : 27061-78-5. EC No.. : 200-664-3. ...
Rahaman, A., and Lazaridis, T. (2014). A thermodynamic approach to alamethicin pore formation. Biochim. et Biophys. Acta - ...
Microsomes with alamethicin were placed on ice for 15 min. In the preliminary study, a change of preincubation time did not ... Materials. UDPGA, alamethicin, aprotinin, bestatin, leupeptin, trypsin inhibitor (type II-S: soybean), estradiol, estradiol 3-O ... 25 μg/ml alamethicin, UDPGA, microsomes, and a substrate. In the preliminary study, the concentration of UDPGA was confirmed to ... In vitro glucuronidation using human liver microsomes and the pore-forming peptide alamethicin. Drug Metab Dispos 28: 560-566. ...
Engelberth, J.; Koch, T.; Schüler, G.; Bachmann, N.; Rechtenbach, J.; Boland, W.: Ion channel-forming alamethicin is a potent ...
Alamethicin F50. 2.5 mg. 149.80 €. -. Toku-e. A120. 1-Alaninechlamydocin. 0.5 mg. 262.15 €. -. Toku-e. ...
Engelberth J., Koch T., Schüler G., Bachmann N., Rechtenbach J., Boland W. ( 2001). Ion channel-forming alamethicin is a potent ...
Differences between Human and Rat Intestinal and Hepatic Bisphenol A Glucuronidation and the Influence of Alamethicin on In ... Differences between Human and Rat Intestinal and Hepatic Bisphenol A Glucuronidation and the Influence of Alamethicin on In ... Differences between Human and Rat Intestinal and Hepatic Bisphenol A Glucuronidation and the Influence of Alamethicin on In ... Differences between Human and Rat Intestinal and Hepatic Bisphenol A Glucuronidation and the Influence of Alamethicin on In ...
Assessment of Respiratory Enzymes in Intact Cells by Permeabilization with Alamethicin. Rasmusson, A. G., Møller, I. M. & ...
A is 5-bit, while B is 8-bit.High-Resolution Electrophysiology on a Chip: Transient Dy- namics of Alamethicin Channel Formation ...
Monitoring the orientational changes of alamethicin during incorporation in bilayer lipid membranes, Langmuir, 2018, 34, 2373- ...
Monitoring the orientational changes of alamethicin during incorporation in bilayer lipid membranes, Langmuir, 2018, 34, 2373- ...
27] Pan, J., Tristram-Nagle, S., and Nagle, J. F. Alamethicin Aggregation in Lipid Membranes. Journal of Membrane Biology 2009; ...
Alamethicin is a channel-forming ionophore. Used as a model for larger channel proteins since it... ...
Alamethicin_F-30. *Ac U P U A U A Q U V U G L U P V U U E Q F OH ... Alamethicin_II. *Ac U P U A U U Q U V U G L U P V U U E Q F OH ... Alamethicin_F-50. *Ac U P U A U A Q U V U G L U P V U U Q Q F OH ...
Alamethicin D12.644.504.111. Alcuronium D3.132.436.255.712.50 D3.132.98.833.50. D3.438.473.402.255.712.50 D3.438.531.85.777.50 ...
Alamethicin D12.644.504.111. Alcuronium D3.132.436.255.712.50 D3.132.98.833.50. D3.438.473.402.255.712.50 D3.438.531.85.777.50 ...
Alamethicin D12.644.504.111. Alcuronium D3.132.436.255.712.50 D3.132.98.833.50. D3.438.473.402.255.712.50 D3.438.531.85.777.50 ...
Alamethicin D12.644.504.111. Alcuronium D3.132.436.255.712.50 D3.132.98.833.50. D3.438.473.402.255.712.50 D3.438.531.85.777.50 ...
Alamethicin D12.644.504.111. Alcuronium D3.132.436.255.712.50 D3.132.98.833.50. D3.438.473.402.255.712.50 D3.438.531.85.777.50 ...
Alamethicin D12.644.504.111. Alcuronium D3.132.436.255.712.50 D3.132.98.833.50. D3.438.473.402.255.712.50 D3.438.531.85.777.50 ...
Alamethicin D12.644.504.111. Alcuronium D3.132.436.255.712.50 D3.132.98.833.50. D3.438.473.402.255.712.50 D3.438.531.85.777.50 ...
Alamethicin D12.644.504.111. Alcuronium D3.132.436.255.712.50 D3.132.98.833.50. D3.438.473.402.255.712.50 D3.438.531.85.777.50 ...
Alamethicin D12.644.504.111. Alcuronium D3.132.436.255.712.50 D3.132.98.833.50. D3.438.473.402.255.712.50 D3.438.531.85.777.50 ...
Alamethicin D12.644.504.111. Alcuronium D3.132.436.255.712.50 D3.132.98.833.50. D3.438.473.402.255.712.50 D3.438.531.85.777.50 ...
Alamethicin D12.644.504.111. Alcuronium D3.132.436.255.712.50 D3.132.98.833.50. D3.438.473.402.255.712.50 D3.438.531.85.777.50 ...
  • Alamethicin is a 20-amino acid channel-forming peptide antibiotic that can function as a monovalent cation ionophore. (discofinechem.com)
  • Alamethicin is a channel-forming ionophore. (fermentek.com)
  • Alamethicin biosynthesis is hypothesized to be catalyzed by alamethicin synthase, a Nonribosomal peptide synthase (NRPS) first isolated in 1975. (wikipedia.org)
  • Ion channel-forming alamethicin is a potent elicitor of volatile biosynthesis and tendril coiling. (mpg.de)
  • Alamethicin is a channel-forming peptide antibiotic, produced by the fungus Trichoderma viride. (wikipedia.org)
  • Alamethicin is a 20-amino acid channel-forming peptide antibiotic isolated from the fungus Trichoderma viride. (discofinechem.com)
  • mPTP) when likened with the PrEC mitochondria, and they do not really undergo bloating actually in the existence of alamethicin, a huge pore developing antibiotic. (techblessing.com)
  • Although there are several sequences of the alamethicin peptide accepted, evidence suggests these all follow the general NRPS mechanism with small variations at select amino acids. (wikipedia.org)
  • The crystal and molecular structure of N-benzyloxycarbonyl-\alpha-aminoisobutyryl-L-prolyl methylamide, the amino terminal dipeptide fragment of alamethicin, has been determined using direct methods. (iisc.ac.in)
  • Explore structures of Alamethicin at the protein data bank Alamethicin in Norine From "A voltage-gated ion channel model inferred from the crystal structure of alamethicin at 1.5-A resolution. (wikipedia.org)

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