Merck, L2884-250MG, Leupeptin

Leupeptin, or N-acetyl-L-leucyl-L-leucyl-L-argininal, is a naturally occurring tripeptide that acts particularly as a serine protease inhibitor and as a cysteine protease inhibitor. Its mechanism of action involves structurally similar covalent binding reactions: •In the active site of serine proteases, leupeptin forms a covalent hemiacetal adduct between the aldehyde group of leupeptin and the hydroxyl group of a serine residue in the enzyme active site. •In the active site of cysteine proteases, the electrophilic (aldehyde) carbon of leupeptin forms a comparable bond with the sulfur atom of a cysteine residue in the enzyme active site.