Chymotrypsine

Chymotrypsine, also known as chymotrypsin in English, is a digestive serine protease produced by the pancreas of many vertebrates. It is synthesized as an inactive zymogen, chymotrypsinogen, and is activated in the small intestine by the protease trypsin. Chymotrypsine belongs to the S1 family of serine proteases and uses a catalytic triad of histidine-57, aspartate-102, and serine-195 to hydrolyze peptide bonds. Its substrate specificity favors peptide bonds on the carboxyl side of bulky hydrophobic residues, particularly phenylalanine, tyrosine, and tryptophan, with some activity on methionine and leucine. The mechanism involves formation of a covalent acyl-enzyme intermediate and a two-step hydrolysis of the peptide bond. Mature chymotrypsin consists of two polypeptide chains formed from the zymogen via proteolytic cleavage and linked by disulfide bonds.

In physiology, chymotrypsine participates in dietary protein digestion in the small intestine. In research and industry, it is widely used to digest proteins for proteomics workflows and protein sequencing. It is inhibited by serine protease inhibitors such as diisopropyl fluorophosphate (DFP) and phenylmethylsulfonyl fluoride (PMSF). Optimum pH is near neutral to mildly alkaline (around 7.8), and activity is greatest near body temperature (approximately 37°C). Chymotrypsine is evolutionarily conserved in vertebrates and is commonly studied as a classic example of serine proteases.