Which enzyme is essential for protein digestion?

Pepsin is essential for protein digestion because it is specifically designed to break down proteins into smaller peptides in the stomach. It is produced as an inactive precursor called pepsinogen, which is activated in the acidic environment of the stomach. Once activated, pepsin can efficiently cleave peptide bonds, primarily those involving aromatic amino acids, which is key for initiating the process of protein catabolism.

Amylase, on the other hand, is an enzyme that facilitates the digestion of carbohydrates, not proteins. Lipase is involved in the digestion of fats, breaking down triglycerides into free fatty acids and glycerol. Gastric lipase also plays a role in fat digestion but is not involved in protein breakdown. Hence, pepsin is the correct enzyme among the options provided for the digestion of proteins.