Clinical Value of Serum Leucine Aminopeptidase Determinations

Abstract

LEUCINE aminopeptidase is a proteolytic enzyme widely distributed in human tissues and body fluids. This report deals with an evaluation of the clinical usefulness of serum assays of this enzyme as determined by the hydrolysis of L-leucyl-beta-naphthylamide. The results obtained with this substrate and their interpretation differ from those obtained with the use of the substrate L-leucylglycine.^{1 2 3} Our method of assay^{4 , 5} is a modification of colorimetric methods described by others.^{6 7 8 9} The validity of this modified method has been established.⁴ With it, the upper limits of normal, taken as 2 standard deviations above the normal mean, are 200 units for males . . .