An oligopeptide ('' oligo-'', "a few"), is a

peptide Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty am ...

consisting of two to twenty

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...

s, including

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 ...

tripeptide A tripeptide is a peptide derived from three amino acids joined by two or sometimes three peptide bonds. As for proteins, the function of peptides is determined by the constituent amino acids and their sequence. In terms of scientific investigati ...

tetrapeptide A tetrapeptide is a peptide, classified as an oligopeptide, since it only consists of four amino acids joined by peptide bonds. Many tetrapeptides are pharmacologically active, often showing affinity and specificity for a variety of receptors ...

s, and other polypeptides. Some of the major classes of naturally occurring oligopeptides include

aeruginosin Pyocins are bacteriocins produced by bacteria belonging to the ''Pseudomonas'' genus. François Jacob described the first pyocin in 1954. Pyocins can be divided into three distinct classes: S-type, R-type, and F-type pyocins. S-type pyocins are col ...

s, cyanopeptolins,

microcystin Microcystins—or cyanoginosins—are a class of cyanotoxins, which are toxins produced by cyanobacteria, sometimes known as blue-green algae. Over 250 different microcystins have been discovered so far, of which microcystin-LR is the most commo ...

s, microviridins, microginins, anabaenopeptins, and

cyclamide Cyclamides are a class of oligopeptides produced by cyanobacteria algae strains such as '' Microcystis aeruginosa''. Some of them can be toxic. Cyclamides are cyclopeptides with either six or eight amino acids, some of which are modified from th ...

s. 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 peptide Nonribosomal peptides (NRP) are a class of peptide secondary metabolites, usually produced by microorganisms like bacterium, bacteria and fungi. Nonribosomal peptides are also found in higher organisms, such as nudibranchs, but are thought to be ma ...

s 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 Amanin is a cyclic peptide. It is one of the amatox ...

- 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 catalyzes the chemical reactions that synthesize RNA from a DNA template. Using the e ...

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 and mushroom, one of many in the genus ''Amanita''. Originating in Europe but later introduced to other parts of the world since the late ...

'', 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. A ...

- 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 catalysis, catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products ...

inhibitor. *

Ceruletide Ceruletide (INN), also known as cerulein or caerulein, is a ten amino acid oligopeptide that stimulates smooth muscle and increases digestive secretions. Ceruletide is similar in action and composition to cholecystokinin. It stimulates gastric, ...

- A specific decapeptide found in the skin of ''Hyla caerulea'', the

Australian green tree frog The Australian green tree frog (''Ranoidea caerulea''/''Litoria caerulea''), also known as simply green tree frog in Australia, White's tree frog, or dumpy tree frog, is a species of tree frog native to Australia and New Guinea, with Introduc ...

. Ceruletide has very much in common with regards to action and composition to

cholecystokinin Cholecystokinin (CCK or CCK-PZ; from Greek ''chole'', "bile"; ''cysto'', "sac"; ''kinin'', "move"; hence, ''move the bile-sac (gallbladder)'') is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat a ...

. It stimulates gastric, biliary, and pancreatic secretion; and certain

smooth muscle Smooth muscle is one of the three major types of vertebrate muscle tissue, the others being skeletal and cardiac muscle. It can also be found in invertebrates and is controlled by the autonomic nervous system. It is non- striated, so-called bec ...

. 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 hormone A hormone (from the Ancient Greek, Greek participle , "se ...

in experimental animal models. *

Glutathione Glutathione (GSH, ) is an organic compound with the chemical formula . It is an antioxidant in plants, animals, fungi, and some bacteria and archaea. Glutathione is capable of preventing damage to important cellular components caused by sources ...

- 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 long chains of amino acids into smaller pieces. It is a serine protease from the PA clan superfamily, found in the dig ...

plasmin Plasmin is an important enzyme () present in blood that degrades many blood plasma proteins, including fibrin thrombus, clots. The degradation of fibrin is termed fibrinolysis. In humans, the plasmin protein (in the zymogen form of plasminogen) i ...

kallikrein Kallikreins are a subgroup of serine proteases, enzymes capable of cleaving peptide bonds in proteins. In humans, plasma kallikrein (encoded by ''KLKB1 gene'') has no known paralogue, while tissue kallikrein-related peptidases (''KLKs'') encode a f ...

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 wi ...

and the

cathepsin Cathepsins (Ancient Greek ''kata-'' "down" and ''hepsein'' "boil"; abbreviated CTS) are proteases (enzymes that degrade proteins) found in all animals as well as other organisms. There are approximately a dozen members of this family, which are d ...

s. *

Netropsin Netropsin (also termed congocidine or sinanomycin) is a polyamide with antibiotic and antiviral activity. Netropsin was discovered by Finlay ''et al.'', and first isolated from the actinobacterium '' Streptomyces netropsis''. It belongs to the cl ...

- 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. *

Pepstatin Pepstatin is a potent inhibitor of aspartyl proteases. It is a hexa-peptide containing the unusual amino acid statine (Sta, (3S,4S)-4-amino-3-hydroxy-6-methylheptanoic acid), having the sequence Isovaleryl-Val-Val-Sta-Ala-Sta (Iva-Val-Val-Sta-Al ...

s - ''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 homology (biology), biological homology between DNA sequence, DNA, RNA sequence, RNA, or Protein primary structure, protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments ...

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 Phalloidin belongs to a class of toxins called phallotoxins, which are found in the death cap mushroom ''( Amanita phalloides)''. It is a rigid bicyclic heptapeptide that is lethal after a few days when injected into the bloodstream. The major s ...

- A very toxic polypeptide isolated mainly from ''

'' (Agaricaceae) or death cap; causes fatal liver, kidney and CNS damage in mushroom poisoning; used in the study of liver damage. * Teprotide - 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 Tuftsin is a tetrapeptide (Thr-Lys-Pro-Arg, TKPR) located in the Fc-domain of the heavy chain of immunoglobulin G (residues 289-292). It has an immunostimulatory effect. It is named for Tufts University where it was first discovered in 1983.Najjar, ...

- ''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.

References

External links

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