Pepsin: The Key Enzyme for Protein Digestion in the Stomach

The enzyme present in the stomach that aids in the digestion of proteins is called pepsin. Pepsin is secreted in the form of pepsinogen, which is inactive, and is then activated in the acidic environment of the stomach by hydrochloric acid. Pepsin works best in acidic conditions and breaks down proteins into smaller peptide fragments, preparing them for further digestion by other enzymes in the small intestine.