A new colorimetric determination of D-amino acid oxidase and urate oxidase activity.

A new method of colorimetric determination of d-amino acid oxidase and urate oxidase using catalase and 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole is reported. This method is based on the combination of two steps of enzyme reactions and colorimetric procedure. The values obtained by this method are satisfactorily correlated with those obtained by the dinitrophenylhydrazine method for d-amino acid oxidase activity and the ultraviolet method for urate oxidase activity and showed good reproducibility and accuracy. It is considered that the method can be useful as a method of activity determination for studying enzyme kinetics and the reaction mechanism.