THE WHOLE STRUCTURE OF THE 13-SUBUNIT OXIDIZED CYTOCHROME-C-OXIDASE AT 2.8 ANGSTROM

The crystal structure of bovine heart cytochrome c oxidase at 2.8 Angs trom resolution with an R Value of 19.9 percent reveals 13 subunits, e ach different from the other, five phosphatidyl ethanolamines, three p hosphatidyl glycerols and two cholates, two hemes A, and three copper, one magnesium, and one zinc. Of 3606 amino acid residues in the dimer , 3560 have been converged to a reasonable structure by refinement, A hydrogen-bonded system, including a propionate of a heme A (heme a), p art of peptide backbone, and an imidazole ligand of Cu-A, could provid e an electron transfer pathway between Cu-A and heme a, Two possible p roton pathways for pumping, each spanning from the matrix to the cytos olic surfaces, were identified, including hydrogen bonds, internal cav ities likely to contain water molecules, and structures that could for m hydrogen bonds with small possible conformational change of amino ac id side chains. Possible channels for chemical protons to produce H2O, for removing the produced water, and for O-2, respectively, were iden tified.