Which digestive enzyme hydrolyzes proteins in the stomach?

• A. Chymotrypsin
• B. Carboxypeptidase A
• C. Trypsin
• D. Pepsin

Answer: (D)

Verified step by step guidance

1. Understand that protein digestion begins in the stomach and continues in the small intestine, involving different enzymes at each stage.
2. Identify the enzyme that is active in the acidic environment of the stomach; this enzyme initiates protein hydrolysis by breaking peptide bonds.
3. Recall that Pepsin is the primary protease enzyme secreted by the stomach lining, functioning optimally at low pH to hydrolyze proteins into smaller peptides.
4. Recognize that Chymotrypsin, Carboxypeptidase A, and Trypsin are pancreatic enzymes that act in the small intestine, not the stomach.
5. Conclude that Pepsin is the digestive enzyme responsible for hydrolyzing proteins in the stomach due to its secretion site and activity conditions.