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 2.4.1.17.
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)

The design, synthesis, modeling and in vitro testing of channel-forming peptides derived from the cys-loop superfamily of ligand-gated ion channels are part of an ongoing research focus. Over 300 different sequences have been prepared based on the M2 transmembrane segment of the spinal cord glycine receptor α-subunit. A number of these sequences are water-soluble monomers that readily insert into biological membranes where they undergo supramolecular assembly, yielding channels with a range of selectivities and conductances. Selection of a sequence for further modifications to yield an optimal lead compound came down to a few key biophysical properties: low solution concentrations that yield channel activity, greater ensemble conductance, and enhanced ion selectivity. The sequence NK[subscript]4-M2GlyR T19R, S22W (KKKKPARVGLGITTVLTMRTQW) addressed these criteria. The structure of this peptide has been analyzed by solution NMR as a monomer in detergent micelles, simulated as five-helix bundles ...
Alamethicin forms voltage-gated ion channels that have moderate cation-selectivity. The enhancement of the cation-selectivity by introducing negatively charged residues at positions 7 and 18 has been studied using the tethered homodimers of alamethicin with Q7 and E18 (di-alm-Q7E18) and its analog with E7 and Q18 (di-alm-E7Q18). In the dimeric peptides, monomer peptides are linked at the N-termini by a disulfide bond. Both the peptides formed long lasting ion channels at cis-positive voltages when added to the cis-side membrane. Their long open duration enabled us to obtain current-voltage (I-V(m)) relations and reversal potentials at the single-channel level by applying a voltage ramp during the channel opening. The reversal potentials measured in asymmetric KCl solutions indicated that ionized E7 provided strong cation-selectivity, whereas ionized E18 little influenced the charge selectivity. This was also the case for the macroscopic charge selectivity determined from the reversal potentials obtained
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The transport of palmitic acid (PA) across planar lipid bilayer membranes was measured using a high specific activity [14C]palmitate as tracer for PA. An all-glass trans chamber was employed in order to minimize adsorbance of PA onto the surface. Electrically neutral (diphytanoyl phosphatidylcholine) and charged (Azolectin) planar bilayers were maintained at open electric circuit. We found a permeability to PA of (8.8 +/- 1.9) x 10(-6) cm s(-1) (n = 15) in neutral and of (10.3 +/- 2.2) x 10(-6) cm s(-1) (n = 5) in charged bilayers. These values fall within the order of magnitude of those calculated from desorption constants of PA in different vesicular systems. Differences between data obtained from planar and vesicular systems are discussed in terms of the role of solvent, radius of curvature, and pH changes. ...
Antimicrobial peptides (AMPs) exhibit a wide range of antimicrobial and antifungal activity and have attracted significant interest as potential antibiotics. However, the mechanism of action of antimicrobial peptides is still poorly understood and, from experimental data, different membrane disruption structural models have been proposed for linear α-helical peptides (the barrel-stave and the toroidal pore models).. We investigate the mechanisms of AMPs in action at different levels of detail: from atomistic [1, 2] to coarse grained molecular dynamics (MD) simulations [3, 4] and even at mixed detail between the two [5]. We proposed a new mechanism for membrane poration by linear antimicrobial peptides: the disordered toroidal pore [1, 2]. Besides, we were able to provide detailed insight on the mechanism of pore-forming cyclic peptides in an effort that brought together simulation results and in vitro measurements of peptide activity [6].. [1] H. Leontiadou, A.E. Mark, S.J. Marrink. ...
Antimicrobial peptides are promising alternative antimicrobial agents compared to conventional antibiotics. Understanding the mode of action is important for their further application. We examined the...
Our Bulletin 836P Solid-State Pressure Sensors measure liquids or gases from -14.5...10,000 psi. These sensors are available in display and non-display models with IO-Link Technology, discrete, and analog outputs. There are various process connections that include flush mount and sanitary connections for application flexibility.. ...
Ag-Sn-phthalocyanine-Ag junctions are shown to exhibit three conductance states. While the junctions are conductive at low bias, their impedance drastically increases above a critical bias. Two-level fluctuations occur at intermediate bias. These characteristics may be used to protect a nanoscale circuit. Further experiments along with calculations reveal that the self-limiting conductance of the junctions is due to reversible changes of the junction geometry ...
SWISS-MODEL Template Library (SMTL) entry for 2k9b.1. Structure and membrane interactions of the antibiotic peptide dermadistinctin K by multidimensional solution and oriented 15N and 31P solid-state NMR spectroscopy
The natural history of Crohn disease (CD) and ulcerative colitis (UC) is characterized by recurrent exacerbations interspersed with periods of inactive disease. The goal of therapy should be to...
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Antibiosis is one of the widespread strategies used by Trichoderma spp. against plant fungal pathogens, the mechanism of which, however, remains poorly understood. Peptaibols are a large family of antimicrobial peptides produced by Trichoderma spp. Our previous study showed that trichokonins, a type of peptaibol from Trichoderma pseudokoningii SMF2, exhibited antibiotic activities against plant fungal pathogens. In this study, we first demonstrated that trichokonin VI (TK VI) induced extensive apoptotic programmed cell death in plant fungal pathogens. For a deeper insight into the apoptotic mechanism involved in the action of TK VI, Fusarium oxysporum was used as a model. Cells of F. oxysporum treated with TK VI showed apoptotic hallmarks, such as exposure of phosphatidylserine, the appearance of reactive oxygen species and fragmentation of nuclear DNA. Moreover, TK VI-treated cells exhibited an accumulation of cytoplasmic vacuoles with loss of the mitochondrial transmembrane potential, and this process
Channel replacement therapy, based on synthetic channel-forming peptides (CFPs) with the ability to supersede defective endogenous ion channels, is a novel treatment modality that may augment existing interventions against ...
Advances in Biological Solid-State NMR: Proteins and Membrane-Active Peptides Advances in Biological Solid-State NMR: Proteins and Membrane-Active Peptides ...
Refined structure of peptaibol zervamicin IIB in methanol solution from trans-hydrogen bond J couplings - Z.A. Yakimenko, Tamara A. Balashova, Tatiana V. Ovchinnikova, A. S. Arseniev, Z.O. Shenkarev
veer = 503.952 cellulose = 503.161 doctored = 503.161 hindustan = 503.161 irrefragable = 503.161 polemic = 503.161 quadruple = 503.161 testy = 503.161 toothpick = 503.161 generalissimo = 502.370 prude = 502.370 rex = 502.370 simplification = 502.370 covey = 501.579 dereliction = 501.579 lesion = 501.579 maidservant = 501.579 meretricious = 501.579 monte = 501.579 parachute = 501.579 phantasmagoria = 501.579 unfasten = 501.579 afeared = 500.788 conjugation = 500.788 dons = 500.788 ducat = 500.788 half-sister = 500.788 importantly = 500.788 largess = 500.788 maestro = 500.788 overall = 500.788 vertebral = 500.788 civilize = 499.997 decry = 499.997 flamboyant = 499.997 keystone = 499.997 obstreperous = 499.997 proselyte = 499.997 reaps = 499.997 rupee = 499.997 despond = 499.205 jj = 499.205 learnedly = 499.205 modish = 499.205 teem = 499.205 vegetative = 499.205 anthropomorphic = 498.414 bookshelves = 498.414 chicanery = 498.414 deteriorate = 498.414 ejection = 498.414 joanne = 498.414 neighbourly ...
Peptaibols: 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.
The lipid composition of the cellular membrane plays an important role in a number of biological processes including the binding of membrane-active peptides. Characterization of membrane binding remains challenging, due to the technical limitations associated with the use of standard biophysical techniques and available membrane models. Here, we investigate the lipid binding properties of two membrane-active peptides, VSTx1, a well characterized ion-channel inhibitor, identified from spider venom, that preferentially binds to anionic lipid mixtures, and AA139 an antimicrobial β-hairpin peptide with uncharacterised lipid binding properties, currently in pre-clinical development. The lipid binding properties of these peptides are elucidated using nanodiscs formed by both linear and circularized (sortase-mediated) forms of a membrane scaffold protein (MSP1D1ΔH5). We find that nanodiscs formed by circularized MSPs-in contrast to those formed by linear MSPs-are sufficiently stable under sample conditions
Title: Antimicrobial Peptides and Peptaibols, Substitutes for Conventional Antibiotics. VOLUME: 16 ISSUE: 28. Author(s):Herve Duclohier. Affiliation:Institut de Biologie et Physiologie Cellulaires, UMR 6187 CNRS-Universite de Poitiers, 1 rue Geoges Bonnet, BP 633, 86022 Poitiers France.. Keywords:Antimicrobial peptides, peptaibols, alamethicin, planar lipid bilayers. Abstract: In this review, the antimicrobial properties of a number of peptides are described. We first deal with helical linear peptides such as the well-known gramicidin, magainins, melittin, and other less well-known or more recently discovered peptides. Then, betasheet peptides (defensins isolated from insects and also from mammalian tissues) and cyclic peptides like amphotericin B are described before the properties of peptaibols (containing the non-coded amino acid Aib) are discussed. Alamethicin remains the prototype of this class and its biophysical properties (mostly focussing on channel- or pore-formation in planar lipid ...
Snyder et al. [29] concluded from electron density profiles of LPS R60 that its charges are located mainly in two distinct planes which are separated by a distance of 1.1 nm. The outer charged plane corresponds to the negatively charged phosphate groups linked to the heptoses in the core region of the LPS, the inner charged plane to the phosphate groups of the lipid A moiety. Using this model, we calculated the surface potential profiles of aggregates composed of those LPS having heptoses substituted with significant numbers of phosphate groups (LPS Rz, LPS R345, LPS R60) as superpositions of the Gouy-Chapman potential profiles ΨI and ΨO for the inner and the outer plane, respectively:. (Eq.1)ΨGC(x) = ΨI exp (- κ x) + ΨO exp (- κ (x - 1.1 nm)) for x ≥ 1.1 nm. where x is the distance from the inner charged plane and κ is the reciprocal Debye- length [27].. ΨGC at the plane of shear corresponds to the ζ-potential. Using Eq. 1, the distance of the plane of shear d2 can be calculated ...
Advances in Planar Lipid Bilayers and Liposomes, Volume 6, continues to include invited chapters on a broad range of topics, covering both main arrangements...
Scientists studying the tiny devices -- called voltage-dependent ion c...Rockefellers Roderick MacKinnon M.D. a Howard Hughes Medical Ins...,MacKinnon,labs,newest,picture,tells,action,potential,story,biological,biology news articles,biology news today,latest biology news,current biology news,biology newsletters
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Syringomycin is a necrosis-inducing lipopeptide toxin synthesized and secreted by the phytopathogen, Pseudomonas syringae pv. syringae. Although small quantities of syringomycin are known to activate a cascade of physiological events in plasma membranes, the mechanism of action of the phytotoxin has never been fully characterized. The objective of this study was to test the hypothesis that the primary mode of action of syringomycin is to form transmembrane pores that are permeable to cations. Accordingly, direct measurement of ion fluxes were performed using artificial bilayers. The hemolytic properties and surface activity of HPLC-purified syringomycin were quanlified by use of an erythrocyte lysis assay and by the drop weight method. Assays were performed using syringomycin form SRE alone or a mixture containing all forms of the phytotoxin. At a threshold concentration of 500 ng/ml, syringomycin induced hemolysis by forming ion channels in membranes. Osmotic protection studies indicated a ...
Background: Social rejection elicits negative mood, emotional distress and neural activity in networks that are associated with physical pain. However, studies assessing physiological reactions to social rejection are rare and results of these studies were found to be ambiguous. Therefore, the present study aimed to examine and specify physiological effects of social rejection.Methods: Participants (N = 50) were assigned to either a social exclusion or inclusion condition of a virtual ball-tossing game (Cyberball). Immediate and delayed physiological (skin conductance level and heart rate) reactions were recorded. In addition, subjects reported levels of affect, emotional states and fundamental needs.Results: Subjects who were socially rejected showed increased heart rates. However, social rejection had no effect on subjects skin conductance levels. Both conditions showed heightened arousal on this measurement. Furthermore, psychological consequences of social rejection indicated the validity of the
Purchase Advances in Planar Lipid Bilayers and Liposomes, Volume 5 - 1st Edition. Print Book & E-Book. ISBN 9780123736871, 9780080466545
Complete information for MT-ND3 gene (Protein Coding), Mitochondrially Encoded NADH:Ubiquinone Oxidoreductase Core Subunit 3, including: function, proteins, disorders, pathways, orthologs, and expression. GeneCards - The Human Gene Compendium
Reactivity: Arabidopsis thaliana, Human, Mouse and more. Compare different MT-ND6 Antibodies. Buy directly at antibodies-online.com!
Dive into the research topics of Characterization of paracetamol UDP-glucuronosyltransferase activity in human liver microsomes. Together they form a unique fingerprint. ...
Klughammer, B., Benz, B., Betz, M., Thume, M., & Dietz, K. - J. (1992). Reconstitution of vacuolar ion channels into planar lipid bilayers. Biochimica et Biophysica Acta, 1104(2), 308-316. doi:10.1016/0005-2736(92)90045- ...
Five Iranian Trichoderma isolates from species T. viride, T. viridescens, T. asperellum, T. longibrachiatum and T. citrinoviride-selected from the Fungal Collection of the Bu Ali Sina University,...
modules name: vdg ,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, Ivd: , Current due to a voltage-dependent conductance , ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,-------------------------------,---------------------------------------, , , p , , 1 , G= g x A x B (1) , , model.A ,A, , , , model.B ,B, , , , 0.0 ,g, , , , 1 ,P, , Ivd = G x (V -E) , , -0 ,E, , , , , , ,-------------------------------,---------------------------------------, , , p , , 2 , Ivd= g x m x h (2) , , model.m ,m, , , , model.h ,h, , , , 0.00 ,g, , , , 1 ,P, , Ivd = G x (V -E) , , 0 ,E, , , , , , ,-------------------------------,---------------------------------------, , p , 3 , G= g x A (3) , L7_K.A ,A, , , 0.18 ,g, , , 1 ,P, , Ivd = G x (V -E) , -80.0 ,E, , , , , ,-------------------------------,---------------------------------------, , , p , , 4 , Ivd= g x m (4) , , model.m ,m, , , , 0.0 ,g, , , , 1 ,P, , Ivd = G x (V -E) ...
modules name: vdg ,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, Ivd: , Current due to a voltage-dependent conductance , ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,-------------------------------,---------------------------------------, , , p , , 1 , G= g x A x B (1) , , model.A ,A, , , , model.B ,B, , , , 0.00 ,g, , , , 1 ,P, , Ivd = G x (V -E) , , 0 ,E, , , , , , ,-------------------------------,---------------------------------------, , , p , , 2 , Ivd= g x m x h (2) , , model.m ,m, , , , model.h ,h, , , , 0.00 ,g, , , , 1 ,P, , Ivd = G x (V -E) , , 0 ,E, , , , , , ,-------------------------------,---------------------------------------, , , p , , 3 , G= g x A (3) , , model.A ,A, , , , 0.00 ,g, , , , 1 ,P, , Ivd = G x (V -E) , , 0 ,E, , , , , , ,-------------------------------,---------------------------------------, , , p , , 4 , Ivd= g x m (4) , , model.m ,m, , , , 0.00 ,g, , , , 1 ,P, , Ivd ...
Abstract: The results of the investigation of changes of parameters of dynamic bipolar charge-voltage and bipolar and unipolar dynamic current-voltage characteristics and transient currents connected with the pulse change of humidity for the samples of por-Si are presented. The view of high voltage current-voltage curves is characteristic for poling processes in the space charge region similar to that observed in the case of typical ionic conductors. Observed phases of transformation of investigated electrophysical characteristics reflect the time scale of processes in the consequence adsorption-dissociation and transfer - desorption. The efficiency of using the methods of dynamic electrophysical characterization for studying characteristics of porous materials under fast humidity changes was demonstrated ...
Korea Medical Hub Promises 3 Benefits!1. The LOWEST price2. Assurance of the HIGHEST satisfaction3. VIP management for every single customer
162. Myoung-Jae Lee, Gyeong-Su Park, David H. Seo, Sung Min Kwon, Hyeon-Jun Lee, Jume-Seo Kim, MinKyung Jung, Chun-Yeol You, Hyangsook Lee, Hee-Goo Kim, Su-Been Pang, Sunae Seo, Hyunsang Hwang, and Sung Kyu Park, Reliable Multivalued Conductance States in TaOx Memristors through Oxygen Plasma-Assisted Electrode Deposition with in Situ-Biased Conductance State Transmission Electron Microscopy Analysis, ACS Appl. Mater. Interfaces 10, 1021 (2018). ...
bcftools call -cO z -r 1 -o LER_ALM_1580_raw_chr1.vcf.gz LER_ALM_1580_raw.bcf bcftools index LER_ALM_1580_raw_chr1.vcf.gz bcftools stats -F /scratch/3/msf/SpeciesForReference/LER_ALM1580/LER_ALM1580.gatk.iteration4.consensus.FINAL.fa -s - LER_ALM_1580_raw_chr1.vcf.gz , LER_ALM_1580_raw_chr1.vcf.gz.stats bcftools view -r 1:461 LER_ALM_1580_raw_chr1.vcf.gz ...
The most widely known peptaibol is alamethicin. Chugh JK, Wallace BA (August 2001). "Peptaibols: models for ion channels". ...
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 only being found in meteorites, and some antibiotics of fungal origin, such as alamethicin and some ...
Toisc go bhfuil an liosta bunaithe ar an leagan Béarla i 'Wikipedia en' beidh an leagan Béarla ar dtús agus an leagan Gaeilge ina dhiaidh. Tá súil agam, nuair atá méid áirithe den liosta aistrithe go Gaeilge gur féidir liosta i nGaeilge a chumadh nó i nGaeilge agus i mBéarla. ...
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 ...
"TOAC spin labels in the backbone of alamethicin: EPR studies in lipid membranes". Biophys. J. 92 (2): 473-481. doi:10.1529/ ...
"TOAC spin labels in the backbone of alamethicin: EPR studies in lipid membranes". Biophys. J. 92 (2): 473-481. PMC 1751395 ...
Potential-dependent conductances in lipid membranes containing alamethicin Message Subject (Your Name) has sent you a message ... From the properties of lipid membranes containing alamethicin in a wide variety of electrolytes, and from other evidence, it is ... Potential-dependent conductances in lipid membranes containing alamethicin. L. G. M. Gordon, D. A. Haydon ... that alamethicin forms transient pores of some 0.6 nm in diameter and that, for small inorganic ions, these are poorly ...
Depending on the alamethicin concentration and the water content in the membrane, alamethicin either perpendicularly inserts ... Our alamethicin-lipid interaction model explains the spontaneous insertion of alamethicin at high aqueous concentration causing ... alamethicin undergoes a transition from the surface state to the insertion state. The insertion of alamethicin would introduce ... Alamethicin is a transmembrane ion channel at low concentration, and a lytic agent of cell membrane at high concentration. It ...
Avhandling: Trichoderma viride alamethicin and plant cells - Action, response and resistance. ... The alamethicin pores allow passage of metabolites and ions and alamethicin can thus be used as a molecular tool for in situ ... In this thesis alamethicin was used for in situ investigations on Nicotiana tabacum BY-2 and Arabidopsis thaliana cell ... Trichoderma viride alamethicin and plant cells - Action, response and resistance. Detta är en avhandling från Media-Tryck ...
... rupture and fuse in response to the addition of both melittin and alamethicin. In the case of alamethicin, but not melittin, ... Effect of α-helical peptides on liposome structure: A comparative study of melittin and alamethicin. Wessman, Per Uppsala ... By means of a competitive binding assay we furthermore show that alamethicin, in line with earlier findings for melittin, ... Melittin, Alamethicin, Magainin, Liposomes, Affinity, Cryo-transmission electron microscopy National Category Physical ...
"Voltage-Dependent Pore Formation and Antimicrobial Activity by Alamethicin and Analogues, The Journal of Membrane Biology" on ... Voltage-Dependent Pore Formation and Antimicrobial Activity by Alamethicin and Analogues. Duclohier, H.; Wróblewski, H. ... Voltage-Dependent Pore Formation and Antimicrobial Activity by Alamethicin and Analogues Duclohier, H. ; Wróblewski, H. 2001-11 ... The demonstration of ar- alamethicin [33] was a landmark, from which new struc- tificial membrane excitability developed by ...
In a 20-ns simulation of a hexameric alamethicin bundle, the main motions are those of individual helices, not of the bundle as ... We have used extended molecular dynamics simulations of alamethicin bundles consisting of 4, 5, 6, 7, and 8 helices in a ... shows that water orientation inside the alamethicin channels is sensitive to the algorithms used. In all cases, water ordering ... Alamethicin is an antimicrobial peptide that forms stable channels with well-defined conductance levels. ...
... Mark Abraham Mark.Abraham at anu.edu.au Tue Nov 6 11:12:45 CET 2007 *Previous message: [gmx-users ...
Alamethicin forms voltage-gated ion channels that have moderate cation-selectivity. The enhancement of the cation-selectivity ... by introducing negatively charged residues at positions 7 and 18 has been studied using the tethered homodimers of alamethicin ... Alamethicin forms voltage-gated ion channels that have moderate cation-selectivity. The enhancement of the cation-selectivity ... Ion channels of N-terminally linked alamethicin dimers: enhancement of cation-selectivity by substitution of Glu for Gln at ...
Insertion of alamethicin occurs in two steps, corresponding to desolvation of the Gln7 side chain, and the backbone of Aib10 ... Polyalanine and alamethicin form stable helices both when inserted in octane and at the water/octane interface, where they ... We present a detailed analysis of the insertion of alamethicin into the octane slab and the influence of the external field on ... At cis-positive potentials, alamethicin does not insert into a phospholipid bilayer in 10 ns of simulation, due to the slow ...
Alamethicin LKT Labs. Alamethicin is a peptabiol peptide initially produced by species of Trichoderma. Alamethicin is an ...
Alamethicin. A rich model for channel behavior journal, January 1984 * Hall, J. E.; Vodyanoy, I.; Balasubramanian, T. M. ... "Reversed" alamethicin conductance in lipid bilayers journal, April 1991 * Taylor, R. J.; de Levie, R. ...
Alamethicin self-assembling in lipid membranes: Concentration dependence from pulsed EPR of spin labels. Physical Chemistry ... Syryamina, V. N., De Zotti, M., Toniolo, C., Formaggio, F., & Dzuba, S. A. (2018). Alamethicin self-assembling in lipid ... Alamethicin self-assembling in lipid membranes : Concentration dependence from pulsed EPR of spin labels. / Syryamina, Victoria ... Syryamina, VN, De Zotti, M, Toniolo, C, Formaggio, F & Dzuba, SA 2018, Alamethicin self-assembling in lipid membranes: ...
Alamethicin. *Alamethicin is a peptide.. *Alamethicin is a well-studied channel-forming peptide that has a prototypical ... ALAMETHICIN. ALBENDAZOLE. ALFUZOSIN. ALKYLATING AGENT. ALLOPURINOL. ALPHA HYDROXY ACID. ALPHA BLOCKER. AMIDRINE. AMILORIDE. ... In this model alamethicin helices associate to form a bundle with a central lumen, like a barrel made of helical peptides as ...
Alamethicin is a short antibiotic peptide produced by the fungus Trichoderma viride. Ion channels formed by Alamethicin are ... In order to determine the opening and closing of the Alamethicin pore, a bilayer containing Alamethicin was deposited onto the ... The goals of this project were to monitor the incorporation of Alamethicin into 1,2-diphytanoyl-sn-glycero-3-phosphocholine ( ... Determining the Structure and Orientation of the Alamethicin Ion Channel in Lipid Membranes using ATR and Electrochemical ...
Biophysical changes induced by cholesterol on phosphatidylcholine artificial biomembranes containing alamethicin oligomers. ...
NMR Investigations of the Structure and Dynamics of Antimicrobial Peptides: The Peptaibol Alamethicin. Thomas Vosegaard and ...
Infrared Spectroscopy as a Probe for the Development of Secondary Structure in the Amino-Terminal Segment of Alamethicin ... Interest in the stereochemistry of Aib containing peptides, stems from the fact that alamethicin [7,8] and the related ... Here, we report the results of an infrared spectroscopic study of synthetic alamethicin fragments and demonstrate the ... Infrared Spectroscopy as a Probe for the Development of Secondary Structure in the Amino-Terminal Segment of Alamethicin. In: ...
The pentapeptide Boc-Leu-Aib-Pro-Val-Aib-OMe, a fragment of alamethicin and suzukacillin, crystallizes in the space group P21, ... Molecular structure of t-butyloxycarbonyl-Leu-Aib-Pro-Val-Aib-methyl ester, a fragment of alamethicin and suzukacillin: A 310- ... a fragment of alamethicin and suzukacillin: A 310-helical pentapeptide Biopolymers, 21 (12). pp. 2461-2472. ISSN 0006-3525 ...
A comparison of alamethicin, gramicidin A, melittin and tetraacetyl melittin. (deposited 20 May 2010 06:48) * Effects of ... A comparison of alamethicin, gramicidin A, melittin and tetraacetyl melittin. (deposited 20 May 2010 05:02) [Currently ... A comparison of alamethicin, gramicidin A, melittin and tetraacetyl melittin. In: Biochemistry International, 11 (3). 357 -363 ... At low Pi (2.5 mM) the order of uncoupling efficiencies is gramicidin A much greater than alamethicin greater than tetraacetyl ...
Alamethicin. A-1286. Options. 5 mg $160.15. 10 mg $288.72. 50 mg $664.59. ...
Alamethicin suppresses methanogenesis and promotes acetogenesis in bioelectrochemical systems.. Zhu X, Siegert M, Yates MD, ...
Martin, D.R., Williams, J.P.: Chemical nature and sequence of alamethicin. Biochem. J. 153, 181-190 (1976)PubMedGoogle Scholar ... Rindfleisch, H., Kleinkauf, H.: Biosynthesis of alamethicin. FEBS Lett. 62, 276-280 (1976)PubMedGoogle Scholar ... Kleinkauf, H., Rindfleisch, H.: Non-ribosomal biosynthesis of the cyclic octadecapeptide alamethicin. Acta microbiol. Acad. Sci ...
... the omission of alamethicin. Alamethicin was used previously (23) to open pores in the membrane to allow NADH to access all of ... Alamethicin has been reported to sequester membrane-bound fatty acids (30) so it may sequester quinones also, and to induce ... 2017) Alamethicin can capture lipid-like molecules in the membrane. J Chem Phys 146:011103. ... 2014) Antimicrobial peptide alamethicin insertion into lipid bilayer: A QCM-D exploration. Colloids Surf B Biointerfaces 116: ...
Voltage-dependent pore activity of the peptide alamethicin correlated with incorporation in the membrane: salt and cholesterol ... Thermodynamic analysis of incorporation and aggregation in a membrane: application to the pore-forming peptide alamethicin. ... Incorporation kinetics in a membrane, studied with the pore-forming peptide alamethicin. ...
जे.सी.-1 की विशिष्टता और सूजन संकेतों 1 सुक्ष्ममापी CCCP और 5 ग्राम / एमएल alamethicin (माइक्रोबियल विष) के साथ परीक्षण किया ...
MtPTP aktivasyonu takiben, 1 mM EGTA, 1 uM CCCP ve 5 ug / ml alamethicin ile sırasıyla Fura FF, JC-1 ve şişme sinyallerin ... JC-1 Özgünlük ve şişme sinyaller 1 uM CCCP ve 5 mg / ml alamethicin (mikrobiyal toksin) ile test edildi. ...
The most widely known peptaibol is alamethicin. Chugh JK, Wallace BA (August 2001). "Peptaibols: models for ion channels". ...
alamethicin. American Laryngological Association. American Lung Association. delta-aminolevulinic acid, see there. Association ...
Alamethicin channel conductance modified by lipid charge. Vicente Manuel Aguilella Fernández, Sergey M. Bezrukov. EUROPEAN ... Lipid Charge Effects in Alamethicin-induced conductance. Vicente Manuel Aguilella Fernández, S.M. Bezrukov. Biophysical Society ...
  • The antimicrobial action of the peptide antibiotic alamethicin (Alm) is commonly related to peptide self-assembling resulting in the formation of voltage-dependent channels in bacterial membranes, which induces ion permeation. (nsu.ru)
  • The natural alpha-helical peptide antibiotic alamethicin forms voltage-gated ion channels in lipid membranes. (lifl.fr)
  • Interaction of the peptide antibiotic alamethicin with bilayer- and non-bilayer-forming lipids: Influence of increasing alamethicin concentration on the lipids supramolecular structures. (mpg.de)
  • By the method of oriented circular dichroism (OCD), we are able to determine the orientation of the alamethicin with respect to the membrane bilayer. (rice.edu)
  • Depending on the alamethicin concentration and the water content in the membrane, alamethicin either perpendicularly inserts into the bilayer or binds parallel to the membrane surface. (rice.edu)
  • By the method of lamellar x-ray diffraction, we found the membrane bilayer thickness reduced by increasing concentration of alamethicin and decreasing relative humidity. (rice.edu)
  • When alamethicin concentration is low, the peptide molecules adsorb near the area of lipid head group, which effectively expands the average cross sectional area of the lipid molecules and makes the hydrocarbon chains more disordered, so that the lipid bilayer becomes thinner than pure lipid membrane. (rice.edu)
  • We have used extended molecular dynamics simulations of alamethicin bundles consisting of 4, 5, 6, 7, and 8 helices in a palmitoyl-oleolyl-phosphatidylcholine bilayer to evaluate and analyze channel models and to link the models to the experimentally measured conductance levels. (ox.ac.uk)
  • At cis-positive potentials, alamethicin does not insert into a phospholipid bilayer in 10 ns of simulation, due to the slow dynamics of the peptide and lipids. (ox.ac.uk)
  • In order to determine the opening and closing of the Alamethicin pore, a bilayer containing Alamethicin was deposited onto the surface of a thioglucose modified Au(111) electrode. (uoguelph.ca)
  • For two AMPs, alamethicin and novicidin, we observe that the majority of the lipids remain in a planar bilayer conformation but that a number of lipids are involved in the peptide anchoring.These lipids display reduced dynamics.Our study supports previous studies showing that alamethicin adopts a transmembrane arrangement without significant disturbance of the surrounding lipids, while novicidin forms toroidal pores at high concentrations leading to more extensive membrane disturbance. (nih.gov)
  • For two AMPs, alamethicin and novicidin, we observe that the majority of the lipids remain in a planar bilayer conformation but that a number of lipids are involved in the peptide anchoring. (nih.gov)
  • The bilayer incorporates bundles of alamethicin molecules (purple) that form pore channels in the membrane. (innovations-report.com)
  • Neutron in‐plane scattering intensity of alamethicin pores in DLPC bilayer at P / L =1/10 hydrated with D 2 O (data +) or with H 2 O (data o). (els.net)
  • Scientists at Lawrence Livermore National Laboratory took an important step in creating a nanobioelectronic device when they combined a silicon nanowire (shown in the picture in gray ), covered it with a lipid bilayer (blue), and incorporated bundles of alamethicin molecules (purple) to form pore channels in the membrane. (medgadget.com)
  • This article is concerned primarily with the mechanism of the potential-dependent conductance induced in artificial lipid membranes by the cyclic polypeptide antibiotic alamethicin. (royalsocietypublishing.org)
  • Alamethicin is a short antibiotic peptide produced by the fungus Trichoderma viride. (uoguelph.ca)
  • Here, we report the results of an infrared spectroscopic study of synthetic alamethicin fragments and demonstrate the development of a $3_{10}$ helical structure at the amino-terminus of the antibiotic. (iisc.ac.in)
  • The activity of rotenone-sensitive NADH:O 2 oxidoreductase, reflecting the overall activity of the respiratory chain, was measured in a mitochondrial fraction by a novel method based on providing access for NADH to intact mitochondria via alamethicin, a channel-forming antibiotic. (diabetesjournals.org)
  • To permit assessment of the electron transport activity despite impermeability of the inner mitochondrial membrane for NADH, the antibiotic alamethicin was used. (diabetesjournals.org)
  • Alamethicin is a channel-forming antibiotic known to increase the permeability of biological membranes through the creation of transmembrane pores up to 20 A in diameter, providing ready access for NADH to enter intact mitochondria, as previously demonstrated with rat skeletal muscle homogenate ( 10 ) and rat heart mitochondria ( 11 ). (diabetesjournals.org)
  • The antibiotic peptaibol alamethicin from Trichoderma permeabilises Arabidopsis root apical meristem and epidermis but is antagonised by cellulase-induced resistance to alamethicin. (mpg.de)
  • Initially, we show that the antimicrobial peptides melittin, alamethicin and magainin 2, in spite of their very different physico-chemical properties and suggested modes of action on membranes, all have high affinity to lipodisks. (diva-portal.org)
  • Observations made with these peptides are distinct as seen from data obtained with the hydrophobic peptide alamethicin. (mdpi.com)
  • Structure and functions of channel-forming peptides: magainins, cecropins, melittin and alamethicin. (tcdb.org)
  • Alamethicin is a membrane active peptide secreted from the soil-living fungus Trichoderma viride. (avhandlingar.se)
  • Alamethicin is a peptabiol peptide initially produced by species of Trichoderma. (thomassci.com)
  • Alamethicin forms voltage-gated ion channels that have moderate cation-selectivity. (semanticscholar.org)
  • Ion channels formed by Alamethicin are voltage-gated due to their large molecular dipoles. (uoguelph.ca)
  • From the properties of lipid membranes containing alamethicin in a wide variety of electrolytes, and from other evidence, it is concluded that the polypeptide reacts to the electric field more probably because it has a large dipole moment than because it binds ions. (royalsocietypublishing.org)
  • Alamethicin remains the prototype of this class and its biophysical properties (mostly focussing on channel- or pore-formation in planar lipid bilayers) were and are still intensively studied. (eurekaselect.com)
  • Klinke, N., Goldermann, M. and Hanke, W.: The properties of alamethicin incorporated into planar lipid bilayers under the influence of microgravity. (uni-bremen.de)
  • When alamethicin concentration reaches the critical point, where membrane structure becomes favorable for the insertion of alamethicin, alamethicin undergoes a transition from the surface state to the insertion state. (rice.edu)
  • The insertion of alamethicin would introduce much water into membrane, so the transition would happen only when relative humidity is high. (rice.edu)
  • Our alamethicin-lipid interaction model explains the spontaneous insertion of alamethicin at high aqueous concentration causing the lysis of membrane. (rice.edu)
  • Voltage-dependent insertion of alamethicin at phospholipid/water and octane/water interfaces. (ox.ac.uk)
  • Insertion of alamethicin occurs in two steps, corresponding to desolvation of the Gln7 side chain, and the backbone of Aib10 and Gly11. (ox.ac.uk)
  • We present a detailed analysis of the insertion of alamethicin into the octane slab and the influence of the external field on the peptide structure. (ox.ac.uk)
  • I could also induce resistance against the pore-forming properties of alamethicin in BY-2 cells by incubating cells with the cell wall degrading enzyme cellulase. (avhandlingar.se)
  • Cryo-transmission electron microscopy was used in combination with turbidity and leakage measurements to explore and compare the membrane perturbing effects of melittin and alamethicin on POPC-based liposomes of varying composition. (diva-portal.org)
  • cholesterol change their shape, rupture and fuse in response to the addition of both melittin and alamethicin. (diva-portal.org)
  • In the case of alamethicin, but not melittin, fusion is effectively prevented by inclusion of 10 mol. (diva-portal.org)
  • By means of a competitive binding assay we furthermore show that alamethicin, in line with earlier findings for melittin, possess high affinity for positively curved lipid surfaces. (diva-portal.org)
  • A comparison of alamethicin, gramicidin A, melittin and tetraacetyl melittin. (iisc.ac.in)
  • At low Pi (2.5 mM) the order of uncoupling efficiencies is gramicidin A much greater than alamethicin greater than tetraacetyl melittin greater than melittin. (iisc.ac.in)
  • At Pi = 100 mM inhibitory effects are observed for alamethicin and tetraacetyl melittin. (iisc.ac.in)
  • Data of six different peptide/lipid systems are shown: alamethicin in diphytanoyl phosphatidylcholine ( DPhPC ), alamethicin in a mixture of dioleoyl phosphatidylcholine ( DOPC ) and dioleoyl phosphatidylethanolamine ( DOPE ), melittin in DPhPC , melittin in DOPC , melittin in palmitoyl‐oleoyl phosphatidylcholine ( POPC ), and melittin in dieicosenoyl phosphatidylcholine (DiC20:1PC). (els.net)
  • In the context of the molecular shape concept, the properties of lipopeptides, including surfactins, are shortly presented, and comparisons with the hydrophobic alamethicin sequence are made. (springer.com)
  • The absence of response in yeast mitochondria was not simply due to structural limitations, since large-amplitude swelling occurred in the presence of alamethicin, a hydrophobic, helical peptide, forming voltage-sensitive ion channels in lipid membranes. (sigmaaldrich.com)
  • As a specific example from Keller's work, alamethicin molecules form ion channels in membranes. (asbmb.org)
  • Also, the cellulase-induced signalling leading to alamethicin resistance needs to be investigated. (avhandlingar.se)
  • It has already been shown from studies of the fluctuations that can be detected in very small membrane currents, that alamethicin forms transient pores of some 0.6 nm in diameter and that, for small inorganic ions, these are poorly selective. (royalsocietypublishing.org)
  • Alamethicin can make pores across membranes with a negative membrane potential, such as the plant plasma membrane. (avhandlingar.se)
  • The alamethicin pores allow passage of metabolites and ions and alamethicin can thus be used as a molecular tool for in situ enzyme measurements. (avhandlingar.se)
  • Alamethicin is an antimicrobial peptide (AMP) that disturbs the lipid layer of the cell membrane, aggregating and forming pores and causing cell lysis. (thomassci.com)
  • This thesis reports the studies of the structure and mechanism of peptide-induced membrane pores by antimicrobial peptide alamethicin and by a peptide named Baxalpha5, which is derived from Bax protein. (rice.edu)
  • Our study supports previous studies showing that alamethicin adopts a transmembrane arrangement without significant disturbance of the surrounding lipids, while novicidin forms toroidal pores at high concentrations leading to more extensive membrane disturbance. (nih.gov)
  • Alamethicin forms barrel-stave channels without significant perturbation of the lipid (d), while novicidin creates toroidal pores in the lipids (e). (nih.gov)
  • Alamethicin adopts transmembrane conformations (Fig. 6d) and novicidin uses the lipids to form toroidal pores with the lipid (Fig. 6e). (nih.gov)
  • He K, Ludtke SJ, Worcester DL and Huang HW (1996) Neutron scattering in the plane of membrane: structure of alamethicin pores. (els.net)
  • The molecular conditions that affects alamethicin membrane association and pore formation, in plasma membranes in vivo, remains to be characterised. (avhandlingar.se)
  • Voltage-Dependent Pore Formation and Antimicrobial Activity by Alamethicin and Analogues Duclohier, H. (deepdyve.com)
  • Alamethicin is a transmembrane ion channel at low concentration, and a lytic agent of cell membrane at high concentration. (rice.edu)
  • The possibility that taurocholate effects may result from non-specific activation of the overt enzyme was excluded by employing the channel-forming peptide alamethicin to effect permeabilization, and by varying the mode of delivery of diacylglycerol substrate to the microsomal membranes. (biochemj.org)
  • Permeabilization using alamethicin gave a slightly higher latent/overt ratio for DGAT. (biochemj.org)
  • 5] . A typical incubation mixture (0.2 mL total volume) contained 50 mM Tris-HCl buffer (pH 7.4), 5 mM MgCl 2 , 5 mM UDPGA, 25 µg/mL alamethicin, 0.25 mg/mL microsomal protein, and 25 - 200 µM morphine. (scirp.org)
  • The IR signature of Alamethicin was determined and different peptide ratios were tested. (uoguelph.ca)
  • The goals of this project were to monitor the incorporation of Alamethicin into 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) model biomimetic membranes and characterize the opening and closing of these incorporated Alamethicin channels. (uoguelph.ca)
  • A detailed comparison of simulations using different methods to treat long-range electrostatic interactions (a twin range cutoff, Particle Mesh Ewald, and a twin range cutoff combined with a reaction field correction) shows that water orientation inside the alamethicin channels is sensitive to the algorithms used. (ox.ac.uk)
  • Polarization Modulation Infrared Reflection Absorption Spectroscopy (PMIRRAS) was used to examine changes in the structure and orientation of Alamethicin as a function of the applied potential. (uoguelph.ca)
  • It also suggests a possible gating mechanism for alamethicin ion channels. (rice.edu)
  • Alamethicin is an antimicrobial peptide that forms stable channels with well-defined conductance levels. (ox.ac.uk)
  • Ion channels of N-terminally linked alamethicin dimers: enhancement of cation-selectivity by substitution of Glu for Gln at position 7. (semanticscholar.org)
  • article{Okazaki2007IonCO, title={Ion channels of N-terminally linked alamethicin dimers: enhancement of cation-selectivity by substitution of Glu for Gln at position 7. (semanticscholar.org)
  • Working with Sol M. Gruner, Keller showed that the conductance state of alamethicin channels changes dramatically when the channels are present in dioleoylphosphatidylethanolamine compared with dioleoylphosphatidylcholine membranes. (asbmb.org)
  • I have successfully used alamethicin to study the regulation of the membrane protein callose synthase and its interactions with the fragile cytoskeleton. (avhandlingar.se)
  • Continuum solvent model calculations of alamethicin-membrane interactions: thermodynamic aspects. (semanticscholar.org)
  • We describe molecular dynamics simulations of the antimicrobial peptide alamethicin in lipid/water and octane/water environments, taking into account an external electric field to mimic the membrane potential. (ox.ac.uk)
  • Attenuated Total Reflection Fourier Transform Infrared spectroscopy (ATR-FTIR) was employed to elucidate the mechanism of Alamethicin incorporation by first spreading vesicles onto the ATR prism. (uoguelph.ca)
  • In this thesis alamethicin was used for in situ investigations on Nicotiana tabacum BY-2 and Arabidopsis thaliana cell suspension cells. (avhandlingar.se)
  • The demonstration of ar- alamethicin [33] was a landmark, from which new struc- tificial membrane excitability developed by planar lipid tural studies sprang also allowing the formulation of hy- bilayers doped with alamethicin [70] indeed struck the potheses on the voltage-dependent membrane insertion minds of many a biophysicist, including electrophysiolo- and the architecture of the oligomeric channel. (deepdyve.com)
  • Analysis and evaluation of channel models: simulations of alamethicin. (ox.ac.uk)
  • Our findings give new insight into the mechanism of channel formation by alamethicin and the structure and dynamics of membrane-associated helices. (ox.ac.uk)
  • In a 20-ns simulation of a hexameric alamethicin bundle, the main motions are those of individual helices, not of the bundle as a whole. (ox.ac.uk)
  • Polyalanine and alamethicin form stable helices both when inserted in octane and at the water/octane interface, where they partition in the same location. (ox.ac.uk)
  • From these two mutually complementary studies we constructed a consistent picture for the interaction between alamethicin and the membrane. (rice.edu)
  • The changes may help to explain the cause of alamethicin resistance in cellulase treated cells. (avhandlingar.se)
  • With this knowledge the possible advantages for the plant of being able to develop a fungus-induced resistance to a membrane active peptide such as alamethicin could also be clarified. (avhandlingar.se)
  • When coexisting with T. Viride, plant roots are exposed to alamethicin, which has the ability to elicit formation of volatile compounds involved in pathogen defence. (avhandlingar.se)