Mode of Inhibition of the Electron Transport System by Phenylhydrazine*

Publisher Website
Google Scholar
Abstract
Inhibition of the electron transport system by phenylhydrazine was studied with mitochondria and submitochondrial particles of rat liver and of beef heart. In order to obtain a maximal inhibition at a given concentration, it was needed to preincubate the particles with the inhibitor for a certain period. The appearence of inhibition required oxygen and depended on temperature. CuSO4 catalysed the autoxidation of phenylhydrazine, and completely oxidized phenylhydrazine had no inhibitory effect on the succinate oxidase system. Therefore, and intermediate in autoxidation of phenylhydrazine seemed to be the inhibitor of the electron transport system in mitochondria. Effects of the inhibitor on each step of reaction in the succinate oxidase system and on the redox state of the cytochrome system showed that phenylhydrazine inhibits the electron transport system at a site between cytochrome b and c1, and that it destroys both cytochrome (c+c1) and a. Since the inhibition occurred without serious chemical changes of cytochromes (c+c1) and a, phenylhydrazine appeared to act primarily on a site between cytochromes b and c1 in the succinate oxidase system.