A suspension of freeze-thawed mitochondria mixed with purple membranes from Halobacteria was illuminated with visible light. It was found that the light exposure prevented inhibition of succinate oxidation. The illumination also led to a decrease in inhibition of the rate of ferricyanide reduction by rat liver mitochondria in the presence of succinate. Both phenomena are explained by the fact that oxalacetate inhibition of succinate dehydrogenase is prevented by light-induced energization of mitochondrial membranes due to the contact with purple membranes.
