Enterokinase activates which pancreatic zymogen?

• A. Chymotrypsinogen
• B. Procarboxypeptidase
• C. Trypsinogen
• D. Proelastase

Answer: (C)

Enterokinase initiates digestion by converting trypsinogen into active trypsin. Produced in the duodenal lining, enterokinase cleaves the activation peptide from trypsinogen, producing trypsin. Once active, trypsin starts the proteolytic enzyme cascade by activating the other pancreatic zymogens—chymotrypsinogen, proelastase, and procarboxypeptidases—by cleaving them to their active forms. So the zymogen directly activated by enterokinase is trypsinogen; the others are activated downstream by trypsin.