Studies on cytochrome oxidase in carbon tetrachloride treated rats.

Cytochrome c oxidase was purified from control and CCl4 treated rats and its kinetic properties were studied. The activity of the enzyme was inhibited by 51% in CCl4 (4 g per kg body weight for 24 hr) treated rats. Studies on the kinetic properties showed that the K(m) of the enzyme increased by 60% while Vmax decreased by 44% in CCl4 treated rats compared to controls. The content of cytochrome aa3 was decreased by 34% while cytochrome b and c were not affected by CCl4 treatment. Phosphatidylcholine, phosphatidylethanolamine and cardiolipin were decreased significantly by 40%, 49% and 60% respectively in CCl4 treated rats. A decrease in the cytochrome aa3 content and a change in the lipid environment of the membrane are probably responsible for a decreased rate of electron transfer from cytochrome c to oxygen.