Effect of citric acid-cycle intermediates on oxaloacetate utilization and succinate oxidation

Evidence that oxaloacetate plays an important rate-regulating role in metabolism through the citric acid cycle is growing, particularly through studies on both animal and plant tissues, demon- strating that the rate of succinate oxidation under different conditions is inversely related to the oxaloacetate concentration and thus influenced by factors affecting the production and removal of the keto acid (Pardee & Potter, 1948; Brummond & Burris, 1953; Tyler, 1955a, b; Wolff & Ball, 1957; Avron & Biale, 1957; Corwin & Schwarz, 1959).This paper reports the results of examination of some other factors affecting the metabolism of oxaloacetate and its capacity to inhibit succinic dehydrogenase.It will be shown that oxaloacetate utilization is inhibited by the presence of some citric acid-cycle intermediates and this inhibition is reflected in a potentiation of the inhibition of succinate oxidation.