Metals and activity of bovine heart cytochrome c oxidase are independent of polypeptide subunits III, VII, a, and b.
Bovine heart cytochrome c oxidase, depleted of polypeptide subunits by alkaline detergent treatment, was characterized with respect to metal content, optical spectral properties, and oxidase activity. Treatment with 1.0% Triton X-100 at pH 9.5 followed by anion-exchange chromatography caused removal of subunit III, subunit VII, and polypeptides a and b. The metal atom stoichiometries of the control and the polypeptide-depleted enzyme were in both cases 2.5Cu/2Fe/1Zn/1Mg with metal-to-protein ratios significantly greater in the latter. The treated enzyme exhibited a red shifted oxidized Soret maximum and bound carbon monoxide upon reduction. Activity was markedly decreased by the treatment but was restored to control levels by incubation with 0.3% Tween 80 at pH 6.0. Therefore, subunit III, subunit VII, polypeptide a, and polypeptide b do not contain Cu, Fe, Zn, or Mg and are not essential for reduction of O2 by ferrocytochrome c.
Yewey
G L
GL
Department of Biochemistry, Colorado State University, Fort Collins 80523.
Caughey
W S
WS
D000818:Animals; D002417:Cattle; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D046911:Macromolecular Substances; D008667:Metalloproteins / Q000502:physiology; D008670:Metals / Q000502:physiology*; D008929:Mitochondria, Heart / Q000201:enzymology*; D013329:Structure-Activity Relationship
D046911:Macromolecular Substances; D008667:Metalloproteins; D008670:Metals; D003576:Electron Transport Complex IV