Inhibition of Cyanide-Resistant Respiration in Pea Cotyledon Mitochondria by Chloroquine

Abstract
The action on mitochondrial respiration of a ubiquinone analog, chloroquine, was studied using purified mitochondria from the cotyledons of germinating peas (P. sativum L. cv. Homesteader). Chloroquine at 3 mM did not inhibit malate or succinate oxidation at pH 7.2, but it did inhibit malate (but not succinate) oxidation at pH 8.2. Cyanide-resistant respiration was inhibited. The role of ubiquinone in the cyanide-resistant respiratory pathway and on the location of the alternate oxidase are discussed.