Superoxide and hydrogen peroxide production in cyanide resistant Arum maculatum mitochondria

Abstract

Submitochondrial particles from Arum maculatum containing a powerful cyanide insensitive oxidase were assayed by various methods to determine the end product of its interaction with oxygen. Using cytochrome c peroxidase to assay the production of H 2O 2 it was possible to detect H 2O 2 formation by Arum submitochondrial particles oxidizing NADH but not when oxidizing succinate. The rate of production of H 2O 2, however, was insufficient to account for the rate of oxygen uptake due to the alternate oxidase. The production of superoxide was determined using the luminol and adrenochrome assays. It was found that some superoxide was produced when Arum submitochondrial particles oxidized NADH but not when they oxidized succinate and again at insufficient rates to account for the rate of oxygen uptake by the alternate oxidase. stoichiometric determination of the ratio of NADH oxidized to oxygen taken up in the presence of 1 mM KCN, sufficient to inhibit catalase activity such that added peroxide remains stable, showed H 2O to be the only detectable product. It is suggested that although both H 2O 2 and superoxide are produced by A. maculatum submitochondrial particles this is not due to the alternate oxidase but may be due to another component of the respiratory chain possibly at the level of the NADH dehydrogenase.