Which enzyme activates trypsinogen to trypsin?

• A. Enteropeptidase
• B. Amylase
• C. Lipase
• D. Zymotrypsin

Answer: (A)

Activation of pancreatic zymogens in the small intestine begins with a specific brush-border enzyme that acts as the first activator. Enteropeptidase (enterokinase) cleaves a small peptide from trypsinogen, converting it into active trypsin. Once trypsin is active, it goes on to activate other proenzymes in the pancreatic juice, such as chymotrypsinogen, proelastase, and procarboxypeptidases, kickstarting the protein-digesting cascade.

Amylase and lipase are enzymes that digest carbohydrates and fats, not activators of trypsinogen. Zymotrypsin is itself produced as a zymogen and is activated by trypsin, not by enteropeptidase.