• Amanitins - Cyclic peptides taken from carpophores of several different mushroom species. They are potent inhibitors of RNA polymerase
  RNA polymerase
  RNA polymerase is an enzyme that produces RNA. In cells, RNAP is needed for constructing RNA chains from DNA genes as templates, a process called transcription. RNA polymerase enzymes are essential to life and are found in all organisms and many viruses...
  
  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, poisonous if ingested by humans or animals.
• Antipain
  Antipain
  Antipain is an oligopeptide used in biochemical research as a protease inhibitor. Specifically, it is an inhibitor of trypsin and papain....
  
   - An oligopeptide produced by various bacteria which acts as a protease inhibitor.
• Ceruletide
  Ceruletide
  Ceruletide , 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, biliary, and pancreatic secretion; and certain smooth muscle...
  
   - 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
  Cholecystokinin
  Cholecystokinin is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein...
  
  . It stimulates gastric, biliary, and pancreatic secretion; and certain smooth muscle
  Smooth muscle
  Smooth muscle is an involuntary non-striated muscle. It is divided into two sub-groups; the single-unit and multiunit smooth muscle. Within single-unit smooth muscle tissues, the autonomic nervous system innervates a single cell within a sheet or bundle and the action potential is propagated by...
  
  . It is used to induce pancreatitis
  Pancreatitis
  Pancreatitis is inflammation of the pancreas. It occurs when pancreatic enzymes that digest food are activated in the pancreas instead of the small intestine. It may be acute – beginning suddenly and lasting a few days, or chronic – occurring over many years...
  
   in experimental animal models.
• Glutathione
  Glutathione
  Glutathione is a tripeptide that contains an unusual peptide linkage between the amine group of cysteine and the carboxyl group of the glutamate side-chain...
  
   - 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
  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....
  
  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
  Trypsin is a serine protease found in the digestive system of many vertebrates, where it hydrolyses proteins. Trypsin is produced in the pancreas as the inactive proenzyme trypsinogen. Trypsin cleaves peptide chains mainly at the carboxyl side of the amino acids lysine or arginine, except when...
  
  , plasmin
  Plasmin
  Plasmin is an important enzyme present in blood that degrades many blood plasma proteins, most notably, fibrin clots. The degradation of fibrin is termed fibrinolysis. In humans, the plasmin protein is encoded by the PLG gene.- Function :...
  
  , kallikrein
  Kallikrein
  Kallikreins are a subgroup of serine proteases, enzymes capable of cleaving peptide bonds in proteins. In humans, plasma kallikrein has no known homologue, while tissue kallikrein-related peptidases encode a family of fifteen closely related serine proteases...
  
  s, papain
  Papain
  Papain, also known as papaya proteinase I, is a cysteine protease enzyme present in papaya and mountain papaya .-Papain family:...
  
   and the cathepsin
  Cathepsin
  Cathepsins are proteases: proteins that break apart other proteins, found in many types of cells including those in all animals. There are approximately a dozen members of this family, which are distinguished by their structure, catalytic mechanism, and which proteins they cleave...
  
  s.
• Netropsin
  Netropsin
  Netropsin is an oligopeptide with antibiotic and antiviral activity.Netropsin was discovered by Finlay et al. and first isolated from the actinobacterium Streptomyces netropsis. It belongs to the class of pyrrole-amidine antibiotics...
  
   - A basic polypeptide 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
  Pepstatin is a potent inhibitor of aspartyl proteases. It is a hexa-peptide containing the unusual amino acid statine , having the sequence Isovaleryl-Val-Val-Sta-Ala-Sta...
  
  s - N-acylated oligopeptides isolated from culture filtrates of Actinomycetes, which act specifically to inhibit acid proteases such as pepsin and renin.
• Peptide T
  Peptide T
  Peptide T is an HIV entry inhibitor discovered in 1986 by National Institutes of Health researchers. Peptide T, and its modified analog Dala1-peptide T-amide , a drug in clinical trials, is a short peptide derived from the HIV envelope protein gp120 which blocks binding and infection of viral...
  
   - 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 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
  Phalloidin is one of a group of toxins from the death cap known as phallotoxins.-Background:Pioneering work on this toxin was done by the Nobel laureate Heinrich Wieland in the 1930s...
  
   - A very toxic polypeptide isolated mainly from Amanita phalloides (Agaricaceae) or death cap; causes fatal liver, kidney and CNS damage in mushroom poisoning; used in the study of liver damage.
• Teprotide
  Teprotide
  Teprotide is nonapeptide which has been isolated from the snake Bothrops jararaca. It is an angiotensin converting enzyme inhibitor , which inhibits the conversion of angiotensin I to angiotensin II and may potentiate some of the pharmacological actions of bradykinin...
  
   - 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
  Tuftsin is a tetrapeptide produced by enzymatic cleavage of the Fc-domain of the heavy chain of immunoglobulin G. It is produced primarily in the spleen.-Function:Its biological activity is related primarily to the immune system function....
  
  - 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.

External links

• http://www.nlm.nih.gov/cgi/mesh/2004/MB_cgi?field=entry&term=Oligopeptides
• http://www.medicalglossary.org/peptides_oligopeptides_definitions.html