Which of the following enzymes is activated by enterokinase (enteropeptidase) secreted by the duodenal mucosa?
- A Pepsinogen to pepsin
- B Trypsinogen to trypsin ✓
- C Chymotrypsinogen to chymotrypsin
- D Procarboxypeptidase to carboxypeptidase
Correct answer: B. Trypsinogen to trypsin
Explanation
Enterokinase is a specific protease on the duodenal brush border that cleaves the hexapeptide from trypsinogen, generating active trypsin. Trypsin then activates all other pancreatic zymogens, including chymotrypsinogen and procarboxypeptidase, making it the master activator. This cascade means the direct substrate of enterokinase is trypsinogen alone. Pepsinogen is activated by gastric acid autocatalytically, not by any intestinal enzyme, so option A is the best distractor to eliminate.
Reference: Guyton and Hall Textbook of Medical Physiology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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