OXIDATION OF REDUCED DIPHOSPHOPYRIDINE NUCLEOTIDE BY CLOSTRIDIUM PERFRINGENS I

Abstract

A Soluble cyanide-insensitive oxidase from C. perfringens catalyzes oxidation of 2 molecules of reduced dephosphopyridine nucleotide (DPN) to 2 of DPN, coupled with the reduction of O2 to 2 H2O. The activity of the oxidase in crude extracts is as great as that of the cytochrome-containing reduced DPN oxidase of the strict aerobe, Azotobacter agile. Traces of peroxide (2 x 10-7 to 3 x 10-6 [image]) are formed during the oxidation of reduced DPN by the clostridial enzyme; however, these coenzyme levels of free peroxide are not intermediates in the over-all oxidation mechanism. There are 2 types of inhibition reaction caused by reduced DPN: 1 depends on peroxide concentration and leads to first order decay of enzyme activity (k = 0.13 minute"-1). The 2d is detected at high concentrations of reduced DPN and causes immediate inhibitions, which are directly proportional to the concentration of reduced nucleotide. Crude extracts of C. perfringens also contain reductases for flavinadenine dinucleotide and menadione. Autoxidation of the reduced form of the latter compounds leads to high peroxide concentrations. These reductase activities are not properties of the purified reduced DPN oxidase.