| Abstract: | 1. Mitochondria prepared from young Arum spadix have enoughcytochrome c oxidase to account for the rate at which succinateis oxidized, but succinoxidase activity increases markedly asthe plants mature so that in old material cytochrome oxidaseactivity is only 10 per cent, of succinoxidase. 2. Disintegration of the mitochondria by vibration with ballotini,treatment with digitonin or incubation in the warm reveals anintra-mitochondrial cytochrome c oxidase probably active enoughto account for the fastest rates of succinate oxidation. 3. Succinic dehydrogenase activity is demonstrated and experimentswith p-chloromercuribenzoate indicate that it plays a part inthe oxidation of succinate. 4. Cyanide completely inhibits both external and internal cytochromeoxidase but even at the earliest stages it only reduces succinoxidaseby about 50 per cent. Antimycin A also inhibits succinoxidaseby about 50 per cent. |
