Which enzyme breaks down proteins into amino acids?

• A. Amylase
• B. Lipase
• C. Trypsin
• D. Pepsin

Answer: (C)

Proteins are digested by proteolytic enzymes called proteases that cut peptide bonds. Among the options, trypsin is the pancreatic protease that acts in the small intestine to digest proteins. It is released as trypsinogen and activated in the gut, and it cleaves peptide bonds on the carboxyl side of lysine and arginine residues, producing smaller peptides. Those peptides are then further broken down by other enzymes into free amino acids for absorption. The other enzymes target different substrates—amylase for starches, lipase for fats, and pepsin also digests proteins but does so in the acidic stomach environment, with pancreatic proteases taking over in the small intestine. So, trypsin is the enzyme that primarily breaks down proteins into amino acids in this context.