title: Zinc is a constituent of bovine heart cytochrome c oxidase preparations.
abstract: Cytochrome c oxidase preparations from bovine heart muscle contain 1 zinc per 2 irons. Metal contents of nine preparations determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) show that Cu, Fe and Zn are the only metals present in significant amounts with average Cu/Fe, Fe/Zn, and Cu/Zn atom ratios of 1.3, 2.1 and 2.8, respectively. Removal of adventitious copper results in a Cu:Fe:Zn stoichiometry of 2:2:1. The zinc is tightly bound. Dialysis against a solution of 1,10-phenanthroline at pH 7.4 or an acidic buffer (pH 4.4) does not remove Zn. Dialysis against 0.8 M KCN at pH 10 causes partial loss of both Cu and Zn. This is the first evidence for the presence of Zn in a cytochrome c oxidase.
mesh_terms: D000818:Animals; D002417:Cattle; D003300:Copper / Q000032:analysis; D003576:Electron Transport Complex IV / Q000032:analysis*; D007501:Iron / Q000032:analysis; D009206:Myocardium / Q000201:enzymology*; D013054:Spectrophotometry, Atomic; D015032:Zinc / Q000032:analysis*
chemical_list: D003300:Copper; D007501:Iron; D003576:Electron Transport Complex IV; D015032:Zinc