Cytochrome oxidase and cytochromes a and a3 in crab mitochondria

Abstract

A study has been made of thecytochrome oxidase and cytochromes [alpha] and [alpha]3 inphosphorylating mitochondria isolated from the hepatopancreas of Carcinus maenas. 50 [mu]M- Hydrogen cyanide inhibits 93% of the respiration due to the oxidation of succinate, fumarate and reduced cytochrome c. In the dark 95% carbon monoxide causes a 20-30% inhibition of respiration. This inhibition is completely reversed by light. Carbon monoxide combines with reduced cytochrome [alpha]3 to form a complex which absorbs light maximally at 430 m[mu] About 51-65% of the absorption of light at 445 m[mu] in the difference spectrum may be ascribed to cytochrome [alpha]3. It is concluded that cytochrome [alpha]3 is the cytochrome oxidase of these mitochondria.