Chymotrypsinogen is the inactive precursor, or zymogen, of the digestive enzyme chymotrypsin, secreted by the pancreas into the small intestine. There it meets trypsin, which clips off a peptide to activate it, unleashing an enzyme that breaks protein chains at aromatic amino acids. Producing digestive enzymes in inactive form protects the pancreas from digesting itself, a safeguard whose failure causes pancreatitis. Chymotrypsin works alongside trypsin and peptidases to reduce dietary protein to absorbable peptides and amino acids. The activation cascade is a elegant example of biochemical control, keeping powerful enzymes harmless until exactly where they are needed.