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Peptaibol
Peptaibols are biologically active peptides containing between seven and twenty amino acid residues, some of which are non-proteinogenic amino acids. In particular, they contain α-aminoisobutyric acid along with other unusual aminoacids such as ethylnorvaline, isovaline and hydroxyproline; the N-terminus is acetylated, and the C-terminal amino acid is hydroxylated to an acid alcohol. They are named pebtaibols due to them being peptides containing α-aminoisobutyric acid (Aib) and ending in an alcohol. They are produced by certain fungi, mainly in the genus ''Trichoderma'', as secondary metabolites which function as antibiotics and antifungal agents. Some are referred to as trichorzianines. They are amphipathic which allows them to form voltage-dependent ion channels in cell membranes which create holes in the membrane making them leaky and leading to the death of the cells. As of 2001, over 317 peptaibols had been identified. The most widely known peptaibol is alamethicin. Refere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trichoderma
''Trichoderma'' is a genus of fungi in the family Hypocreaceae that is present in all soils, where they are the most prevalent culturable fungi. Many species in this genus can be characterized as opportunistic avirulent plant symbionts. This refers to the ability of several ''Trichoderma ''species to form mutualistic endophytic relationships with several plant species. The genomes of several ''Trichoderma'' species'' ''have been sequenced and are publicly available from the JGI. Taxonomy The genus was described by Christiaan Hendrik Persoon in 1794, but the taxonomy has remained difficult to resolve. For a long time, it was considered to consist of only one species, ''Trichoderma viride'', named for producing green mold. Subdivision In 1991, Bissett divided the genus into five sections, partly based on the aggregate species described by Rifai: *''Pachybasium'' (20 species) *''Longibrachiatum'' (10 species) *''Trichoderma'' *''Saturnisporum'' (2 species) *''Hypocreanum'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha amino acids appear in the genetic code. Amino acids can be classified according to the locations of the core structural functional groups, as Alpha and beta carbon, alpha- , beta- , gamma- or delta- amino acids; other categories relate to Chemical polarity, polarity, ionization, and side chain group type (aliphatic, Open-chain compound, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling life ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alamethicin
Alamethicin is a channel-forming peptide antibiotic, produced by the fungus ''Trichoderma viride''. It belongs to peptaibol peptides which contain the non-proteinogenic amino acid residue Aib (2-aminoisobutyric acid). This residue strongly induces formation of alpha-helical structure. The peptide sequence is: Ac-Aib-Pro-Aib-Ala-Aib-Ala-Gln-Aib-Val-Aib-Gly-Leu-Aib-Pro-Val-Aib-Aib-Glu-Gln-Phl (Ac = acetyl, Phl = phenylalaninol, Aib = 2-Aminoisobutyric acid) In cell membranes, it forms voltage-dependent ion channels by aggregation of four to six molecules. Biosynthesis Alamethicin biosynthesis is hypothesized to be catalyzed by alamethicin synthase, a Nonribosomal peptide synthase (NRPS) first isolated in 1975. 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. Beginning with the acylation of the N terminal of the first aminoisobutiric acid on the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peptide
Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. A polypeptide is a longer, continuous, unbranched peptide chain. Hence, peptides fall under the broad chemical classes of biological polymers and oligomers, alongside nucleic acids, oligosaccharides, polysaccharides, and others. A polypeptide that contains more than approximately 50 amino acids is known as a protein. Proteins consist of one or more polypeptides arranged in a biologically functional way, often bound to ligands such as coenzymes and cofactors, or to another protein or other macromolecule such as DNA or RNA, or to complex macromolecular assemblies. Amino acids that have been incorporated into peptides are termed residues. A water molecule is released during formation of each amide bond.. All peptides except cyclic pep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-proteinogenic Amino Acid
In biochemistry, non-coded or non-proteinogenic amino acids are distinct from the 22 proteinogenic amino acids (21 in eukaryotesplus formylmethionine in eukaryotes with prokaryote organelles like mitochondria) which are naturally encoded in the genome of organisms for the assembly of proteins. However, over 140 non-proteinogenic amino acids occur naturally in proteins and thousands more may occur in nature or be synthesized in the laboratory. Chemically synthesized amino acids can be called unnatural amino acids. Unnatural amino acids can be synthetically prepared from their native analogs via modifications such as amine alkylation, side chain substitution, structural bond extension cyclization, and isosteric replacements within the amino acid backbone. Many non-proteinogenic amino acids are important: * intermediates in biosynthesis, * in post-translational formation of proteins, * in a physiological role (e.g. components of bacterial cell walls, neurotransmitters and toxins), * n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
α-aminoisobutyric Acid
2-Aminoisobutyric acid (also known as α-aminoisobutyric acid, AIB, α-methylalanine, or 2-methylalanine) is the non-proteinogenic amino acid with the structural formula H2N-C(CH3)2-COOH. It is rare in nature, having been only found in meteorites, and some antibiotics of fungal origin, such as alamethicin and some lantibiotics. Synthesis In the laboratory, 2-aminoisobutyric acid may be prepared from acetone cyanohydrin, by reaction with ammonia followed by hydrolysis. Industrial scale synthesis can be achieved by the selective hydroamination of methacrylic acid. Biological activity 2-Aminoisobutyric acid is not one of the proteinogenic amino acids and is rather rare in nature (''cf.'' non-proteinogenic amino acids). It is a strong helix inducer in peptides due to Thorpe–Ingold effect of its gem-dimethyl group. Oligomers of AIB form 310 helices. Ribosomal incorporation into peptides 2-Aminoisobutyric acid is compatible with ribosomal elongation of peptide synthesis. Katoh ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxyproline
(2''S'',4''R'')-4-Hydroxyproline, or L-hydroxyproline ( C5 H9 O3 N), is an amino acid, abbreviated as Hyp or O, ''e.g.'', in Protein Data Bank. Structure and discovery In 1902, Hermann Emil Fischer isolated hydroxyproline from hydrolyzed gelatin. In 1905, Hermann Leuchs synthesized a racemic mixture of 4-hydroxyproline. Hydroxyproline differs from proline by the presence of a hydroxyl (OH) group attached to the gamma carbon atom. Production and function Hydroxyproline is produced by hydroxylation of the amino acid proline by the enzyme prolyl hydroxylase following protein synthesis (as a post-translational modification). The enzyme catalyzed reaction takes place in the lumen of the endoplasmic reticulum. Although it is not directly incorporated into proteins, hydroxyproline comprises roughly 4% of all amino acids found in animal tissue, an amount greater than seven other amino acids that are translationally incorporated. Animals Collagen Hydroxyproline is a major compon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-terminus
The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the amine group is bonded to the carboxylic group of another amino acid, making it a chain. That leaves a free carboxylic group at one end of the peptide, called the C-terminus, and a free amine group on the other end called the N-terminus. By convention, peptide sequences are written N-terminus to C-terminus, left to right (in LTR writing systems). This correlates the translation direction to the text direction, because when a protein is translated from messenger RNA, it is created from the N-terminus to the C-terminus, as amino acids are added to the carboxyl end of the protein. Chemistry Each amino acid has an amine group and a carboxylic group. Amino acids link to one another by peptide bonds which form through a dehydration reaction that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Metabolite
Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animals, or plants, which are not directly involved in the normal growth, development, or reproduction of the organism. Instead, they generally mediate ecological interactions, which may produce a selective advantage for the organism by increasing its survivability or fecundity. Specific secondary metabolites are often restricted to a narrow set of species within a phylogenetic group. Secondary metabolites often play an important role in plant defense against herbivory and other interspecies defenses. Humans use secondary metabolites as medicines, flavourings, pigments, and recreational drugs. The term secondary metabolite was first coined by Albrecht Kossel, a 1910 Nobel Prize laureate for medicine and physiology in 1910. 30 years later a Polish botanist Friedrich Czapek described secondary metabolit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of such infections. They may either kill or inhibit the growth of bacteria. A limited number of antibiotics also possess antiprotozoal activity. Antibiotics are not effective against viruses such as the common cold or influenza; drugs which inhibit viruses are termed antiviral drugs or antivirals rather than antibiotics. Sometimes, the term ''antibiotic''—literally "opposing life", from the Greek roots ἀντι ''anti'', "against" and βίος ''bios'', "life"—is broadly used to refer to any substance used against microbes, but in the usual medical usage, antibiotics (such as penicillin) are those produced naturally (by one microorganism fighting another), whereas non-antibiotic antibacterials (such as sulfonamides and antiseptics) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphipathic
An amphiphile (from the Greek αμφις amphis, both, and φιλÃα philia, love, friendship), or amphipath, is a chemical compound possessing both hydrophilic (''water-loving'', polar) and lipophilic (''fat-loving'') properties. Such a compound is called amphiphilic or amphipathic. Common amphiphilic substances are soaps, detergents, and lipoproteins. The phospholipid amphiphiles are the major structural component of cell membranes. Amphiphiles are the basis for a number of areas of research in chemistry and biochemistry, notably that of lipid polymorphism. Organic compounds containing hydrophilic groups at both ends of the molecule are called bolaamphiphile, bolaamphiphilic. The micelles they form in the aggregate are prolate. Structure The lipophilic group is typically a large hydrocarbon Moiety (chemistry), moiety, such as a long chain of the form CH3(CH2)n, with n > 4. The hydrophilic group falls into one of the following categories: # charged groups #* anionic. Examples ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voltage-dependent Ion Channel
Voltage-gated ion channels are a class of transmembrane proteins that form ion channels that are activated by changes in the electrical membrane potential near the channel. The membrane potential alters the conformation of the channel proteins, regulating their opening and closing. Cell membranes are generally impermeable to ions, thus they must diffuse through the membrane through transmembrane protein channels. They have a crucial role in excitable cells such as neuronal and muscle tissues, allowing a rapid and co-ordinated depolarization in response to triggering voltage change. Found along the axon and at the synapse, voltage-gated ion channels directionally propagate electrical signals. Voltage-gated ion-channels are usually ion-specific, and channels specific to sodium (Na+), potassium (K+), calcium (Ca2+), and chloride (Cl−) ions have been identified. The opening and closing of the channels are triggered by changing ion concentration, and hence charge gradient, between t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
