Abstract
A new method was presented for estimation of various deaminases such as leucine aminopeptidase (LAP), adenosine deaminase, trypsin, benzylamine oxidase and so on.
The principle of the method consists in measurement of ammonia liberated by the actions of deaminases with a direct colorimetric determination of ammonia reported by Fujii and Okuda.
Leucine amide was used for estimation of LAP in our new method. On the other hand, leucine naphthylamide was widely used for the assay of this enzyme in the present clinical examination.
It was demonstrated that rat liver contained several isozymes which showed different substrate specificities toward leucine amide and leucine naphthylamide.
In human hepatitis and CCl4-treated rats, elevated plasma LAP hydrolyzes preferentially leucine amide as compared with leucine naphthylamide.
The result suggests that leucine amide is a preferable substrate for estimation of plasma LAP in clinical examination.
