Pancreatic zymogens secreted into the duodenum require proteolytic activation. Once intestinal enteropeptidase initiates the process, which single enzyme is responsible for activating chymotrypsinogen, proelastase and procarboxypeptidases?

• A Enteropeptidase acting on each zymogen directly
• B Chymotrypsin, generated autocatalytically, cleaving the remaining zymogens
• C Trypsin, generated from trypsinogen, cleaving the other zymogens ✓
• D Pepsin refluxed from the stomach

Explanation

Enteropeptidase performs only one physiologic cleavage: conversion of trypsinogen to trypsin. Trypsin then activates all the other pancreatic zymogens, including more trypsinogen, creating an amplification cascade anchored to a single initiating event. Option A overstates the role of enteropeptidase, option B gets the sequence backwards since chymotrypsinogen must first be activated by trypsin, and pepsin is confined to the stomach and plays no duodenal role.

Reference: Lippincott Illustrated Reviews: Biochemistry, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.