Chymotrypsins

Literature References: A group of major proteolytic enzymes in the pancreatic juice. Produced in the form of inactive chymotrypsinogen by the acinous cells of pancreas, and carried as such by the pancreatic juice into the duodenum where they are activated by trypsin. They split secondary amide or peptide bonds, carboxylic or phenolic ester bonds and even carbon-carbon bonds. Their main function is to hydrolyze peptide bonds during the intestinal digestion of proteins. Cattle pancreatic juice contains nearly equal quantities of two chymotrypsinogens: A which is cationic at pH 8 and B which is anionic. Chymotrypsinogen A is converted by trypsin into p-chymotrypsin. In the presence of large amounts of trypsin, p-chymotrypsin is degraded to d-chymotrypsin. In the presence of small amounts of trypsin, p-chymotrypsin is autolyzed to a-chymotrypsin. After long standing a-chymotrypsin gives rise to b- and g-chymotrypsin which differ from it in their crystal habits. Prepn of p- and d-chymotrypsins: Bettelheim, Neurath, J. Biol. Chem. 212, 241 (1955). Prepn of a-, b-, g- and d-chymotrypsins (and chymotrypsin B): Laskowski, Methods Enzymol. 2, 8 (1955). Amino acid sequence of chymotrypsinogen A: Hartley, Nature 201, 1284 (1964); Melorin et al., Biochim. Biophys. Acta 130, 543 (1966); of chymotrypsinogen B: Hartley et al., Nature 207, 1157 (1965); Smillie et al., ibid. 218, 343 (1968). Reviews: Bender et al., J. Polym. Sci. 49, 75 (1961); Desnuelle, The Enzymes vol. 4, P. D. Boyer et al., Eds. (Academic Press, New York, 2nd ed., 1960) pp 93-118; Kraut; Blow; Hess, ibid. vol. 3 (3rd ed., 1971) 165, 185, 213.