Final answer:
Proteins affect the composition of pancreatic juice by triggering the release of enzymes that help in protein digestion and the hydrolysis of peptide bonds.
Step-by-step explanation:
The presence of protein affects the composition of pancreatic juice in several ways. Pancreatic juice contains a variety of enzymes that are required for the digestion of proteins. When proteins are present in the small intestine, the hormone cholecystokinin is released, which triggers the release of pancreatic juice by the pancreas. This juice contains enzymes like trypsinogen, chymotrypsinogen, and procarboxypeptidases, which are activated in the small intestine and catalyze the hydrolysis of peptide bonds in protein chains.