Studies on the Mechanism of Oxidative Phosphorylation

X. THE EFFECT OF CYTOCHROME c ON ENERGY-LINKED PROCESSES IN SUBMITOCHONDRIAL PARTICLES

From the ¹ From the Institute for Enzyme Research, University of Wisconsin, Madison, Wisconsin 53706

Submitochondrial particles, in contrast to heavy mitochondria, are not made deficient in cytochrome c by extraction with isotonic KCl, and they are essentially impermeable to exogenously added cytochrome c. When the particles are made permeable with deoxycholate, however, the electron transfer chain interacts with cytochrome c.

Submitochondrial particles which are deficient in cytochrome c may be prepared, however, from mitochondria rendered deficient in cytochrome c. These depleted submitochondrial particles show a decreased rate of those energy-linked processes which are dependent on substrate oxidation, such as phosphorylation, reduction of exogenous diphosphopyridine nucleotide by succinate, and transhydrogenation between pyridine nucleotides. Also, the deficiency in cytochrome c appears to cause a decreased efficiency in these processes. In contrast, when adenosine triphosphate is the source of energy, the systems catalyzing the processes of reversed electron transfer and transhydrogenation are intact and fully functional in the deficient particles.

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