[L-arginine assay with the use of arginase I]

A highly selective and sensitive method for the quantitative determination of L-arginine (Arg) with a fluorescent detection of the reaction product has been developed. The method is based on the use of human liver arginase I isolated from a recombinant producer strain, yeast Hansenula polymorpha, and 2,3-butanedione monoxime, which is used to detect carbamide--the product of enzymatic reactions. The linear concentration range for determining Arg in the final reaction mixture varies from 0.2 to 250 μM, and the detection limit is 0.16 μM. Tests of the new method using commercial Arg-containing pharmaceutical preparations showed a high correlation (R = 1.0) of the results with the manufacturer's data and the results of other methods for Arg detection.