Chymotrypsin C (CTRC) is a member of the peptidase S1 family. CTRC is a serum calcium-decreasing factor that has chymotrypsin-like protease activity. CTRC has broad substrate specificity, but prefers tocleave on the carboxyl side of hydrophobic residues. CTRC is expressed primarily in the pancreas, and is secreted into the digestive tract. CTRC plays a protective role in the pancreas by mitigating premature trypsinogen activation through degradation. It has been proposed that CTRC is a key regulator of digestive zymogen activation and is a physiological coactivator of digestive carboxypeptidases proCPA1 and proCPA2. The mutation of CTRC gene encodes the digestive enzyme CTRC contribute to the development of pancreatitis.