title: Integral complexes of cytochrome c oxidase contain three coppers.
abstract: Metal contents have been determined in beef heart cytochrome c oxidase by inductively coupled plasma atomic emission spectroscopy. Integral complexes of this enzyme contain three copper and two iron atoms, as well as one zinc and one magnesium atom (Cu: 2, 91 +/- 0, 13; Fe: 2, 05 +/- 0, 17; Zn: 1, 03 +/- 0, 03; Mg: 1, 01 +/- 0, 10). The combination of these results with those reported for the c1 aa3-oxidase from Thermus thermophilus leads to the conclusion that subunit I is the universal two coppers and two hemes a binding catalytic unit common to all oxidases of the aa3-type. Subunit II, which binds the third copper ion, functions as an electron conducting unit, transferring electrons from cytochrome c to the four redox centers in subunit I. Preliminary titration experiments with NADH reveal, in agreement with this catalytic organisation, the presence of five redox centers.
authors.affiliation: Abteilung Physiologische Chemie, Rheinisch-Westfälische Technische Hochschule, Aachen, Fed. Rep. Germany.
authors.forename: G C
authors.initials: GC
authors.lastname: Steffens
authors.forename: G
authors.initials: G
authors.lastname: Buse
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000693:Anaerobiosis; D000818:Animals; D002417:Cattle; D003300:Copper / Q000032:analysis*; D003576:Electron Transport Complex IV / Q000302:isolation & purification / Q000378:metabolism*; D046911:Macromolecular Substances; D008667:Metalloproteins / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D009206:Myocardium / Q000201:enzymology
chemical_list: D000596:Amino Acids; D046911:Macromolecular Substances; D008667:Metalloproteins; D003300:Copper; D003576:Electron Transport Complex IV