Ocular aminopeptidase activity and distribution in the albino rabbit

Ocular aminopeptidase activity in the albino rabbit was determined using L-leucine-, L-alanine-, and L-arginine-4-methoxy-2-naphthylamide as substrates. The corneal epithelium and the iris-ciliary body were found to be the most active, followed by, in turn, conjunctiva and corneal stroma, lens and aqueous humor, and lastly tears. The pattern of substrate hydrolysis suggests that a common dominant aminopeptidase is present in these tissues except the conjunctiva. While the role of these peptidases in ocular physiology is unknown, they may play a role in limiting the entry of topically applied peptides into the eye.