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Peptides

Definition:	Any member of a class of compounds of low molecular weight which yield two or more amino acids on hydrolysis. Formed by loss of water from the NH2 and COOH groups of adjacent amino acids, they are known as di-, tri-, tetra- (etc.) peptides, depending on the number of amino acids in the molecule. Peptides form the constituent parts of proteins. (Dorland, 27th ed)
Notes:	/anal: consider also PEPTIDE MAPPING; GASTRIC INHIBITORY POLYPEPTIDE & PANCREATIC POLYPEPTIDE are also available; fewer than 13 amino acids = OLIGOPEPTIDES; FUNGAL PEPTIDES see FUNGAL PROTEINS is available; peptide structure: coord PEPTIDES or specific pe

Peptides Categories.

	Antibiotics, Peptide - Antibiotic group of PEPTIDES, many of which are CYCLIC PEPTIDES. They are generally effective against GRAM-POSITIVE BACTERIA and act by inhibiting peptidoglycan synthesis in bacterial cell walls.
	Antimicrobial Cationic Peptides - 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.
	Charybdotoxin - A 37-amino acid residue peptide isolated from the scorpion Leiurus quinquestriatus hebraeus. It is a neurotoxin that inhibits calcium activated potassium channels.
	Diazepam Binding Inhibitor - An 86-amino acid polypeptide, found in central and peripheral tissues, that displaces diazepam from the benzodiazepine recognition site on the gamma-aminobutyric acid receptor (RECEPTORS, GABA). It also binds medium- and long-chain acyl-CoA esters and serves as an acyl-CoA transporter. This peptide regulates lipid metabolism.
	Disintegrins - A family of polypeptides purified from snake venoms, which contain the arginine-glycine-aspartic acid (RGD) sequence. The RGD tripeptide binds to integrin receptors and thus competitively inhibits normal integrin-ligand interactions. Disintegrins thus block adhesive functions and act as platelet aggregation inhibitors.
	Distamycins - Oligopeptide antibiotics from Streptomyces distallicus. Their binding to DNA inhibits synthesis of nucleic acids.
	Edeine - Basic peptide antibiotic from Bacillus brevis. It exhibits broad-spectrum antibacterial activity and inhibits bacterial DNA synthesis.
	Fibrinopeptide A - Two small peptide chains removed from the N-terminal segment of the alpha chains of fibrinogen by the action of thrombin during the blood coagulation process. Each peptide chain contains 18 amino acid residues. In vivo, fibrinopeptide A is used as a marker to determine the rate of conversion of fibrinogen to fibrin by thrombin.
	Fibrinopeptide B - Two small peptide chains removed from the N-terminal segment of the beta chains of fibrinogen by the action of thrombin. Each peptide chain contains 20 amino acid residues. The removal of fibrinopeptides B is not required for coagulation.
	Myocardial Depressant Factor - A low molecular weight peptide of about 800-1000 having a negative inotropic effect. It is released into the circulation during experimental hemorrhagic pancreatitis, severe ischemia, and postoligemic shock.
	Neuropeptides - Peptides released by NEURONS as intercellular messengers. Many neuropeptides are also hormones released by non-neuronal cells.
	Oligopeptides - Peptides composed of between two and twelve amino acids.
	Peptide Fragments - Partial proteins formed by partial hydrolysis of complete proteins.
	Peptide Library - A collection of cloned peptides, or chemically synthesized peptides, frequently consisting of all possible combinations of amino acids making up an n-amino acid peptide.
	Peptides, Cyclic
	Peptoids - Polymers of N-SUBSTITUTED GLYCINES containing chiral centers at the a-position of their side chains. These oligomers lack HYDROGEN BONDING donors, preventing formation of the usual intrachain hydrogen bonds but can form helices driven by the steric influence of chiral side chains.
	Phosphopeptides
	Polygeline - A 3.5 per cent colloidal solution containing urea-cross-linked polymerized peptides. It has a molecular weight of approximately 35,000 and is prepared from gelatin and electrolytes. The polymeric solution is used as a plasma expander.
	Protein Sorting Signals - Amino acid sequences found in transported proteins that selectively guide the distribution of the proteins to specific cellular compartments.
	Tissue Polypeptide Antigen - Serological tumor marker composed of a molecular complex of cytokeratins 8, 18, and 19. It is used in the diagnosis and staging of bronchogenic carcinoma.
	Tyrothricin - A polypeptide antibiotic mixture obtained from Bacillus brevis. It consists of a mixture of three tyrocidines (60%) and several gramicidins (20%) and is very toxic to blood, liver, kidneys, meninges, and the olfactory apparatus. It is used topically.

Peptides Definitions and Terms

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