The regulation of xanthine oxidase. Inhibition by reduced nicotinamide-adenine dinucleotide of rat liver xanthine oxidase type D and of chick liver xanthine dehydrogenase

Abstract

1. Rat liver xanthine oxidase type D (NAD(+)-dependent) and chick liver xanthine oxidase are inhibited by NADH, which competes with NAD(+). 2. The addition of a NADH-reoxidizing system in the assay of these enzyme activities is proposed. 3. Rat liver xanthine oxidase type O (oxygen-dependent) is not affected by NADH.