title: Transformation of the CuA redox site in cytochrome c oxidase into a mononuclear copper center.
abstract: Subunit II of the aa3 type cytochrome c oxidase contains a binuclear copper center (CuA) which functions as the entry point for electrons donated by cytochrome c. We have introduced site-specific mutations in residues liganding the CuA center in the oxidase of the bacterium Paracoccus denitrificans; the purified, fully assembled enzyme complexes were analyzed by various techniques, including EPR, optical spectroscopy, and total-reflection X-ray fluorescence spectrometry, to determine metal to protein ratios. In the C216S mutant, the binuclear CuA site is transformed into a mononuclear copper center. In contrast to wild type, the C216S mutant does no longer exhibit the characteristic absorption band in the near-infrared region of the optical spectrum that has been assigned to CuA. These major changes in the CuA site of this mutant correlate with an almost complete loss in catalytic activity.
authors.affiliation: Institute of Biochemistry/Molecular Genetics, University of Frankfurt, Biozentrum, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Zickermann
authors.forename: A
authors.initials: A
authors.lastname: Wittershagen
authors.forename: B O
authors.initials: BO
authors.lastname: Kolbesen
authors.forename: B
authors.initials: B
authors.lastname: Ludwig
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D003300:Copper / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000378:metabolism*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009206:Myocardium / Q000201:enzymology; D010084:Oxidation-Reduction; D010231:Paracoccus denitrificans / Q000201:enzymology*; D017354:Point Mutation; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry
chemical_list: D046911:Macromolecular Substances; D011994:Recombinant Proteins; D003300:Copper; D003576:Electron Transport Complex IV