Abstract
Succinate dehydrogenase is inhibited by citrate and β-hydroxybutyrate in a complex manner, both in mitochondria and submitochondrial particles. Kinetics of inhibition in the particles points to a competitive component in the mechanism involved. Pyruvate, α-ketoglutarate, malate, and glutamate stimulate oxidation of succinate by mitochondria. Stimulation by α-ketoglutarate and glutamate is not influenced by the presence of rotenone. Stimulation by pyruvate is higher in the absence of rotenone and increases significantly in the presence of K+ and valinomycin. Pyruvate supplies in mitochondria reducing equivalents for malate dehydrogenase operating in the reverse direction-reduction of oxaloacetate to malate. Stimulation by malate is higher in the presence of rotenone.