The hydrolysis of amino acyl-β-naphthylamides by plasma aminopeptidases

Historically, the study of aminopeptidase activity in mammalian systems has been directed primarily toward tissue extracts. This work culminated in the isolation and characterization of the classical leucine aminopeptidase ( Smith and Hill, 1960 ). Little attempt has been made to characterize the aminopeptidases of normal plasma and serum, and perhaps it is for this reason that the activity has been tacitly identified with tissue leucine aminopeptidase (LAP), and commonly designated serum LAP. Behal et al. (1963) have chromatographically resolved the LAP activity of human blood into a number of aminopeptidase components. In this report, some distinguishing properties are described for a variety of aminopeptidases which can occur in blood plasma. The aminopeptidase activity of normal plasma could not be attributed to the presence of leucine aminopeptidase.