Effectors of the mammalian plasma membrane NADH-oxidoreductase system. Short-chain ubiquinone analogues as potent stimulators.

Abstract

In the presence of effectors variations in the two recognized activities of the plasma membrane NADH-oxidoreductase system were studied in separate, specific in vitro assays. We report here that ubiquinone analogues that contain a short, less hydrophobic side chain than coenzyme Q-10 dramatically stimulate the NADH-oxidase activity of isolated rat liver plasma membranes whereas they show no effect on the reductase activity of isolated membranes. If measured in assays of the NADH:ferricyanide reductase of living cultured cells these compounds have only a limited effect; the oxidase activity of whole cells is not measurable in our hands. We have furthermore identified selective inhibitors of b..