If pepsin digesting an actual protein substrate, the product would be

• A. peptides
• B. amino acids
• C. peptides and amino acids
• D. BAPNA

Answer: (C)

Pepsin is a stomach protease that cleaves peptide bonds within proteins, producing smaller chains called peptides. It acts as an endopeptidase, meaning it cuts within the protein to yield shorter peptide fragments rather than freeing individual amino acids. Therefore, the immediate products of pepsin acting on an actual protein substrate are peptides (ranging from dipeptides up to smaller oligopeptides). Free amino acids would require further hydrolysis by other proteases later in the digestive process, not by pepsin alone. Substrates like BAPNA are synthetic and not representative of pepsin’s action on real protein substrates. So the correct idea is that the digestion yields peptides.