A Continuous Spectrophotometric Method for the Determination of Leucine Aminopeptidase

[摘要] A new method to assay the enzyme, leucine aminopeptidase (LAP; L-leucyl-peptide hydrolase—3.4.1.1), is described. The technic is an extension of the conventional glutamic-pyruvic transaminase (GPT) reaction. Serum LAP is allowed to react with the substrate L-leucyl-L-alanine to quantitatively generate alanine. This alanine, in the presence of excess α-ketoglutaric acid and GPT, rapidly forms pyruvate, which is converted to lactate by excess lactic dehydrogenase (LDH). Reduced nicotinamide adenine dinucleotide (NAD) is quantitatively oxidized in this reaction. The change in reduced NAD concentration is followed by continuous spectrophotometry at 340 mµ.

[学科分类] 过敏症与临床免疫学