Chymotrypsin

Chymotrypsin is synthesized by pancreatic acinar cells as an inactive precursor, chymotrypsinogen, that is secreted to the duodenum and activated via trypsin-induced cleavage. It also induces its own activation by cleaving essential amino acid residues in the oxyanion hole to produce α-Chymotrypsin, which is a more stable form than π-Chymotrypsin. Residues His-57, Asp-102, and Ser-195 form the catalytic triad while residues 189–195, 214–220, and 225–228 form the primary substrate-binding pocket called S1 binding pocket. Residue 189 in the polar serine residue that lies at the bottom of the S1 binding pocket. Chymotrypsin favors aromatic residues like phenylalanine, tyrosine, and tryptophan but may hydrolyze other bonds in peptides at slower rates.