The indophenol reaction in biological oxidations

Abstract

The Nadi reagent, dimethyl-p-phenylenediamine hydrochloride and [alpha]-naphthol, gave a positive indophenol reaction during the oxidation of hypoxanthine by xanthine oxidase in the presence of peroxidase. A specific oxidase was not necessary to produce the indophenol reaction. Methods are described for preparing xanthine oxidase from milk and liver. Several samples of yeast, before and after warming, were tested for their reduction of methylene blue. The methylene blue technique was shown to be unreliable as a means of measuring the reducing systems in the yeast cell.