The colorimetric determination of leucine aminopeptidase in urine and serum of normal subjects and patients with cancer and other diseases

✍ Scribed by Julius A. Goldbarg; Alexander M. Rutenburg

• Publisher: John Wiley and Sons
• Year: 1958
• Tongue: English
• Weight: 698 KB
• Volume: 11
• Category: Article
• ISSN: 0008-543X
• DOI: 10.1002/1097-0142(195803/04)11:2<283::aid-cncr2820110209>3.0.co;2-8

✦ Synopsis

HE FIRST demonstration of "leucylpepti-T dase" as a component of erepsin was made by measuring the rate of liberation of carboxyl groups from L-leucylglycine.6 However, since this substrate was hydrolyzed by enzymes other than leucylpeptidase, L-leucinamide, a more specific substrate was synthesized.' Gomori4 developed a more precise colorimetric and histe chemical method to study tissue aminopeptidase, based on the formation of azo dyes from the naphthylamine moiety liberated by enzymatic hydrolysis of glycylor alanyl-p-naphthylamide. Green et a1.6 and Folk and Burstones assayed enzymatic activity of mammalian tissues and serum by measuring the p-naphthylamine liberated by hydrolysis of L-leucyl-P-naphthylamide hydrochloride.

The present report deals with a new method for the colorimetric measurement of leucine aminopeptidase activity in urine and an improved procedure for the assay of enzymatic activity in tissues and serum, the kinetics o f the urinary and serum enzyme, and the assay of this enzyme in the urine and serum of normal subjects and patients with cancer and other diseases.

Methods

Reagents. The reagents used included the following: a substrate solution composed of a From the departments of Surgery, Beth Israel Hospital and Harvard Medical School, Boston, Mass.