Structural studies on bovine heart cytochrome c oxidase

► Metal, lipid and protein assembly of bovine cytochrome c oxidase. ► O2 reduction by O2 binding to Fe2 +, followed by non-sequential 3-electron reduction. ► Positive charges of low spin heme, upon oxidation, pump protons electrostatically. ► X-ray and mutational identification of proton pump system of cytochrome c oxidase.