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An oligopeptide, often just called
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. ...
('' oligo-'', "a few"), consists of two to twenty
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 ...
s and can include
dipeptide A dipeptide is an organic compound derived from two amino acids. The constituent amino acids can be the same or different. When different, two isomers of the dipeptide are possible, depending on the sequence. Several dipeptides are physiological ...
s, tripeptides, tetrapeptides, and pentapeptides. Some of the major classes of naturally occurring oligopeptides include aeruginosins,
cyanopeptolin Cyanopeptolins (CPs) are a class of oligopeptides produced by Microcystis and Planktothrix algae strains, and can be neurotoxic. The production of cyanopeptolins occurs through nonribosomal peptides synthases (NRPS). Chemistry CPs are, in general ...
s, microcystins,
microviridin The microviridins are a class of serine protease inhibitors produced by various genera of cyanobacteria. Recent genome mining has shown that the biosynthetic gene cluster responsible for microviridin biosynthesis is much more prevalent, found in ...
s, microginins, anabaenopeptins, and cyclamides. Microcystins are best studied, because of their potential toxicity impact in drinking water. A review of some oligopeptides found that the largest class are the cyanopeptolins (40.1%), followed by microcystins (13.4%).


Production

Oligopeptide classes are produced by nonribosomal peptides synthases (NRPS), except cyclamides and microviridins are synthesized through ribosomic pathways.


Examples

Examples of oligopeptides include: *
Amanitins Amanitin may refer to several related amatoxins: * α-Amanitin * β-Amanitin * γ-Amanitin * ε-Amanitin See also * Amatoxin, a class of toxic compounds that include the amanitins * Amanin, another amatoxin {{Chemistry index ...
- Cyclic peptides taken from carpophores of several different mushroom species. They are potent inhibitors of
RNA polymerase In molecular biology, RNA polymerase (abbreviated RNAP or RNApol), or more specifically DNA-directed/dependent RNA polymerase (DdRP), is an enzyme that synthesizes RNA from a DNA template. Using the enzyme helicase, RNAP locally opens th ...
s in most eukaryotic species, the prevent the production of mRNA and protein synthesis. These peptides are important in the study of transcription. Alpha-amanitin is the main toxin from the species ''
Amanita phalloides ''Amanita phalloides'' (), commonly known as the death cap, is a deadly poisonous basidiomycete fungus, one of many in the genus ''Amanita''. Widely distributed across Europe, but now sprouting in other parts of the world, ''A. phalloi ...
'', poisonous if ingested by humans or animals. *
Antipain Antipain is an oligopeptide that is isolated from actinomycetes and used in biochemical research as a protease inhibitor of trypsin and papain. It was discovered in 1972 and was the first natural peptide found that contained an ureylene group. ...
- An oligopeptide produced by various bacteria which acts as a
protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the ...
inhibitor. * Ceruletide - A specific decapeptide found in the skin of ''Hyla caerulea'', the Australian green tree frog. Ceruletide has very much in common with regards to action and composition to cholecystokinin. It stimulates gastric, biliary, and pancreatic secretion; and certain
smooth muscle Smooth muscle is an involuntary non- striated muscle, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It is divided into two subgroups, single-unit and multiunit smooth muscle. Within single-unit ...
. It is used to induce
pancreatitis Pancreatitis is a condition characterized by inflammation of the pancreas. The pancreas is a large organ behind the stomach that produces digestive enzymes and a number of hormones. There are two main types: acute pancreatitis, and chronic p ...
in experimental animal models. * Glutathione - A tripeptide with many roles in cells. It conjugates to drugs to make them more soluble for excretion, is a cofactor for some enzymes, is involved in protein disulfide bond rearrangement and reduces peroxides. *
Leupeptin Leupeptin, also known as ''N''-acetyl-L-leucyl-L-leucyl-L-argininal, is a naturally occurring protease inhibitor that can inhibit cysteine, serine and threonine peptidases. It is often used during ''in vitro'' experiments when a specific enzymati ...
s - A group of acylated oligopeptides produced by Actinomycetes that function as protease inhibitors. They have been known to inhibit to varying degrees
trypsin Trypsin is an enzyme in the first section of the small intestine that starts the digestion of protein molecules by cutting these long chains of amino acids into smaller pieces. It is a serine protease from the PA clan superfamily, found in the d ...
, plasmin, kallikreins,
papain Papain, also known as papaya proteinase I, is a cysteine protease () enzyme present in papaya (''Carica papaya'') and mountain papaya (''Vasconcellea cundinamarcensis''). It is the namesake member of the papain-like protease family. It has wide ...
and the cathepsins. * Netropsin - A basic oligopeptide isolated from '' Streptomyces netropsis''. It is cytotoxic and its strong, specific binding to A-T areas of DNA is useful to genetics research. * Pepstatins - ''N''-acylated oligopeptides isolated from culture filtrates of Actinomycetes, which act specifically to inhibit acid proteases such as pepsin and renin. * Peptide T - ''N''-(''N''-(''N''(2)-(''N''-(''N''-(''N''-(''N''-D-Alanyl L-seryl)-L-threonyl)-L-threonyl) L-threonyl)-L-asparaginyl)-L-tyrosyl) L-threonine. Octapeptide sharing
sequence homology Sequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a ...
with HIV envelope protein gp120. It may be useful as antiviral agent in AIDS therapy. The core pentapeptide sequence, TTNYT, consisting of amino acids 4-8 in peptide T, is the HIV envelope sequence required for attachment to the CD4 receptor. * Phalloidin - A very toxic polypeptide isolated mainly from ''
Amanita phalloides ''Amanita phalloides'' (), commonly known as the death cap, is a deadly poisonous basidiomycete fungus, one of many in the genus ''Amanita''. Widely distributed across Europe, but now sprouting in other parts of the world, ''A. phalloi ...
'' (Agaricaceae) or death cap; causes fatal liver, kidney and CNS damage in mushroom poisoning; used in the study of liver damage. *
Teprotide Teprotide is nonapeptide which has been isolated from the snake '' Bothrops jararaca''. It is an angiotensin converting enzyme inhibitor (ACE inhibitor) which inhibits the conversion of angiotensin I to angiotensin II and may potentiate some of t ...
- A man made nonapeptide (Pyr-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro) which is exactly the same as the peptide from the venom of the snake, Bothrops jararaca. It inhibits kininase II and angiotensin I and has been proposed as an antihypertensive agent. * Tuftsin - ''N''(2)-((1-(''N''(2)-L-Threonyl)-L-lysyl)-L-prolyl)-L-arginine. A tetrapeptide manufactured in the spleen by enzymatic cleavage of a leukophilic gamma-globulin. It stimulates the phagocytic activity of blood polymorphonuclear leukocytes and neutrophils in particular. The peptide is located in the Fd fragment of the gamma-globulin molecule.


See also

* Micropeptide *
Oligoester An oligoester is an ester oligomer chain containing a small number of repeating ester units (monomers). Oligoesters are short analogs of polymeric polyesters. An example is oligo-(''R'')-3-hydroxybutyrate. See also * Oligopeptide An oligopept ...
*
Oligomer In chemistry and biochemistry, an oligomer () is a molecule that consists of a few repeating units which could be derived, actually or conceptually, from smaller molecules, monomers.Quote: ''Oligomer molecule: A molecule of intermediate relati ...
* Oligopeptidase * Peptide synthesis *
Protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the ...


References


External links

{{Wiktionary * Structural Biochemistry/Proteins/Amino Acids (Wikibooks) Peptides