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How do pancreatic enzymes break proteins into peptides and amino acids?

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USDA MyPlate dietary guidelines — human nutrition MyPlate, a revised set of dietary guidelines introduced by the U.S. Department of Agriculture (USDA) in 2011, divides the four basic food groups (fruits, grains, protein, and vegetables) into sections on a plate, the size of each section representing the relative dietary proportions of each food group. The small blue circle shown at the upper right illustrates the inclusion and recommended proportion of dairy products in the diet.

Pancreatic enzymes break down proteins through a highly regulated process of proteolysis. The pancreas secretes inactive precursors—known as zymogens—including trypsinogen, chymotrypsinogen, proelastase, and procarboxypeptidase, to prevent the organ from digesting itself.12

Once these precursors reach the small intestine, an enzyme called enterokinase activates trypsinogen into trypsin. Trypsin then triggers the activation of the remaining pancreatic proteases. The process proceeds in two main stages:13

Initial Breakdown: Endopeptidases—specifically trypsin, chymotrypsin, and elastase—cleave internal bonds within protein chains via hydrolysis, reducing them to smaller peptides.13
Final Breakdown: Carboxypeptidases act on these peptides by sequentially splitting off individual amino acids from the terminal ends of the chains.43

These resulting amino acids and small peptides are then absorbed by the cells of the intestinal wall.13