Fluorometric enzymatic assay of l-arginine.

The enzymes of l-arginine (further - Arg) metabolism are promising tools for elaboration of selective methods for quantitative Arg analysis. In our study we propose an enzymatic method for Arg assay based on fluorometric monitoring of ammonia, a final product of Arg splitting by human liver arginase I (further - arginase), isolated from the recombinant yeast strain, and commercial urease. The selective analysis of ammonia (at 415nm under excitation at 360nm) is based on reaction with o-phthalaldehyde (OPA) in the presence of sulfite in alkali medium: these conditions permit to avoid the reaction of OPA with any amino acid.