The chymotrypsins, of which there are several, are serine proteasesderived from the inactive precursor Chymotrypsinogen-A (Alpha–Chymotrypsinogen) and B, which are present in the pancreas and pancreatic juice. Chymotrypsinogen-A is activated by Trypsin, and depending on the method of activation, the principle chymotrypsins may be obtained. These are referred to as Alpha, beta, gamma, delta and pi chymotrypsins.Chymotrypsin specificity: hydrolysis of peptide bonds formed by hydrophobic amino acid residues such as Tyrosine, Phenylalanine and Tryptophan. It hydrolases tyrosyl, tryptophanyl, phenylalanyl peptides, amides and esters. Slow hydrolysis also occurs with aspartate, glutamine, histidine, leucine, lysine, methionine, serine and threonine..