Effect of Diet and Digestive Processes on Proteolytic Enzymes

Abstract

The effect of digestive processes on proteolytic enzymes was determined by comparing the properties of trypsin and chymotrypsin in pancreatic extracts and in intestinal contents of rats fed protein-free or 15% casein diets. Results of studies involving acidification, dialysis, and chromatography of the enzyme solutions demonstrated that the structural properties of trypsin and chymotrypsin were altered in the small intestine. The presence of dietary protein in upper intestinal contents protected the enzymes; hence, changes in their properties must have been a result of proteolysis of the enzyme molecules concurrent with a retention of activity during the early stages of their digestion. The protective effect of dietary protein also demonstrated that exogenous protein was the preferred substrate, and thus was digested more rapidly than endogenous protein.