chymotrypsin, proteolytic, or protein-digesting, enzyme active in the mammalian intestinal tract. It catalyzes the hydrolysis of proteins, degrading them into smaller molecules called peptides. Peptides are further split into free amino acids. Chymotrypsin is produced in the pancreas as the inactive, or zymogen, form chymotrypsinogen. Along with other digestive enzymes of the pancreas, chymotrypsinogen is carried in the pancreatic juice through the pancreatic duct into the duodenum. There chymotrypsinogen is activated by another enzyme, trypsin, and by molecules of active chymotrypsin. Partly because it was one of the first enzymes available commercially in crystalline form, chymotrypsin has been studied extensively.