Related Research Articles
Chymotrypsin (EC 3.4.21.1, chymotrypsins A and B, alpha-chymar ophth, avazyme, chymar, chymotest, enzeon, quimar, quimotrase, alpha-chymar, alpha-chymotrypsin A, alpha-chymotrypsin) is a digestive enzyme component of pancreatic juice acting in the duodenum, where it performs proteolysis, the breakdown of proteins and polypeptides. Chymotrypsin preferentially cleaves peptide amide bonds where the side chain of the amino acid N-terminal to the scissile amide bond (the P1 position) is a large hydrophobic amino acid (tyrosine, tryptophan, and phenylalanine). These amino acids contain an aromatic ring in their side chain that fits into a hydrophobic pocket (the S1 position) of the enzyme. It is activated in the presence of trypsin. The hydrophobic and shape complementarity between the peptide substrate P1 side chain and the enzyme S1 binding cavity accounts for the substrate specificity of this enzyme. Chymotrypsin also hydrolyzes other amide bonds in peptides at slower rates, particularly those containing leucine at the P1 position.
A protease is an enzyme that catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. They do this by cleaving the peptide bonds within proteins by hydrolysis, a reaction where water breaks bonds. Proteases are involved in many biological functions, including digestion of ingested proteins, protein catabolism, and cell signaling.
Chymosin or rennin is a protease found in rennet. It is an aspartic endopeptidase belonging to MEROPS A1 family. It is produced by newborn ruminant animals in the lining of the abomasum to curdle the milk they ingest, allowing a longer residence in the bowels and better absorption. It is widely used in the production of cheese.
A metalloproteinase, or metalloprotease, is any protease enzyme whose catalytic mechanism involves a metal. An example is ADAM12 which plays a significant role in the fusion of muscle cells during embryo development, in a process known as myogenesis.
Plasmepsins are a class of at least 10 enzymes produced by the Plasmodium falciparum parasite. There are ten different isoforms of these proteins and ten genes coding them respectively in Plasmodium. It has been suggested that the plasmepsin family is smaller in other human Plasmodium species. Expression of Plm I, II, IV, V, IX, X and HAP occurs in the erythrocytic cycle, and expression of Plm VI, VII, VIII, occurs in the exoerythrocytic cycle. Through their haemoglobin-degrading activity, they are an important cause of symptoms in malaria sufferers. Consequently, this family of enzymes is a potential target for antimalarial drugs.
Aspergillopepsin I is an enzyme. This enzyme catalyses the following chemical reaction
Subtilisin is a protease initially obtained from Bacillus subtilis.
Aspartic proteases are a catalytic type of protease enzymes that use an activated water molecule bound to one or more aspartate residues for catalysis of their peptide substrates. In general, they have two highly conserved aspartates in the active site and are optimally active at acidic pH. Nearly all known aspartyl proteases are inhibited by pepstatin.
Kexin is a prohormone-processing protease, specifically a yeast serine peptidase, found in the budding yeast. It catalyzes the cleavage of -Lys-Arg- and -Arg-Arg- bonds to process yeast alpha-factor pheromone and killer toxin precursors. The human homolog is PCSK4. It is a family of subtilisin-like peptidases. Even though there are a few prokaryote kexin-like peptidases, all kexins are eukaryotes. The enzyme is encoded by the yeast gene KEX2, and usually referred to in the scientific community as Kex2p. It shares structural similarities with the bacterial protease subtilisin. The first mammalian homologue of this protein to be identified was furin. In the mammal, kexin-like peptidases function in creating and regulating many differing proproteins.
In molecular biology, Proteinase K is a broad-spectrum serine protease. The enzyme was discovered in 1974 in extracts of the fungus Parengyodontium album. Proteinase K is able to digest hair (keratin), hence, the name "Proteinase K". The predominant site of cleavage is the peptide bond adjacent to the carboxyl group of aliphatic and aromatic amino acids with blocked alpha amino groups. It is commonly used for its broad specificity. This enzyme belongs to Peptidase family S8 (subtilisin). The molecular weight of Proteinase K is 28,900 daltons.
Nepenthesin is an aspartic protease of plant origin that has so far been identified in the pitcher secretions of Nepenthes and in the leaves of Drosera peltata. It is similar to pepsin, but differs in that it also cleaves on either side of Asp residues and at Lys┼Arg. While more pH and temperature stable than porcine pepsin A, it is considerably less stable in urea or guanidine hydrochloride. It is the only known protein with such a stability profile.
Oryzin is an enzyme. This enzyme catalyses the following chemical reaction
Signal peptidase I is an enzyme. This enzyme catalyses the following chemical reaction
Streptopain is an enzyme. This enzyme catalyses the following chemical reaction
Aspergilloglutamic peptidase, also called aspergillopepsin II is a proteolytic enzyme. The enzyme was previously thought be an aspartic protease, but it was later shown to be a glutamic protease with a catalytic Glu residue at the active site, and was therefore renamed aspergilloglutamic peptidase.
Penicillopepsin is an enzyme. This enzyme catalyses the following chemical reaction
Rhizopuspepsin is an enzyme. This enzyme catalyses the following chemical reaction
Endothiapepsin is an enzyme. This enzyme catalyses the following chemical reaction
Scytalidocarboxyl peptidase B, also known as Scytalidoglutamic peptidase and Scytalidopepsin B is a proteolytic enzyme. It was previously thought to be an aspartic protease, but determination of its molecular structure showed it to belong a novel group of proteases, glutamic protease.
Peptidyl-Asp metalloendopeptidase is an enzyme. This enzyme catalyses the following chemical reaction
References
- ↑ Arima K, Yu J, Iwasaki S (1970). "Milk-clotting enzyme from Mucor pusillus var. lindt". Methods Enzymol. 19: 446–459. doi:10.1016/0076-6879(70)19033-1.
- ↑ Ottesen M, Rickert W (1970). "The acid protease of Mucor miehei". Methods Enzymol. 19: 459–460. doi:10.1016/0076-6879(70)19034-3.
- ↑ Sternberg M (December 1972). "Bond specificity, active site and milk clotting mechanism of the Mucor miehei protease". Biochimica et Biophysica Acta (BBA) - Protein Structure. 285 (2): 383–92. doi:10.1016/0005-2795(72)90324-8. PMID 4573298.
- ↑ Oka T, Ishino K, Tsuzuki H, Morihara K, Arima K (1973). "On the specificity of a rennin-like enzyme from Mucor pusillus". Agric. Biol. Chem. 37 (5): 1177–1184. doi: 10.1271/bbb1961.37.1177 .
- ↑ Baudys M, Foundling S, Pavlík M, Blundell T, Kostka V (August 1988). "Protein chemical characterization of Mucor pusillus aspartic proteinase. Amino acid sequence homology with the other aspartic proteinases, disulfide bond arrangement and site of carbohydrate attachment". FEBS Letters. 235 (1–2): 271–4. doi: 10.1016/0014-5793(88)81277-8 . PMID 3042459.
