What is a typical substrate for a protease such as peptidase?

• A. Carbohydrate
• B. Nucleic acid
• C. Protein fragment called peptide
• D. Lipid

Answer: (C)

Proteases specialize in breaking peptide bonds found in proteins. Their typical substrates are peptide chains—short or long sequences of amino acids that come from proteins. A peptide is essentially a fragment of a protein, and proteases catalyze the hydrolysis of bonds within those chains to produce smaller peptides or individual amino acids. In contrast, other enzyme types target different kinds of bonds: carbohydrates are acted on by carbohydrases, nucleic acids by nucleases, and lipids by lipases. So a protein fragment called a peptide is the best description of what a protease commonly acts on.