title: Reaction mechanism of bovine heart cytochrome c oxidase.
abstract: The 1.9 A resolution X-ray structure of the O2 reduction site of bovine heart cytochrome c oxidase in the fully reduced state indicates trigonal planar coordination of CuB by three histidine residues. One of the three histidine residues has a covalent link to a tyrosine residue to ensure retention of the tyrosine at the O2 reduction site. These moieties facilitate a four electron reduction of O2, and prevent formation of active oxygen species. The combination of a redox-coupled conformational change of an aspartate residue (Asp51) located near the intermembrane surface of the enzyme molecule and the existence of a hydrogen bond network connecting Asp51 to the matrix surface suggest that the proton-pumping process is mediated at Asp51. Mutation analyses using a gene expression system of the Asp51-containing enzyme subunit yield results in support of the proposal that Asp51 plays a critical role in the proton pumping process.
authors.affiliation: Department of Life Science, University of Hyogo, Kamigohri Akoh, Hyogo 678-1297, Japan. yoshi@sci.u-hyogo.ac.jp
authors.forename: Shinya
authors.initials: S
authors.lastname: Yoshikawa
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Muramoto
authors.forename: Kyoko
authors.initials: K
authors.lastname: Shinzawa-Itoh
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Aoyama
authors.forename: Tomitake
authors.initials: T
authors.lastname: Tsukihara
authors.forename: Takashi
authors.initials: T
authors.lastname: Ogura
authors.forename: Kunitoshi
authors.initials: K
authors.lastname: Shimokata
authors.forename: Yukie
authors.initials: Y
authors.lastname: Katayama
authors.forename: Hideo
authors.initials: H
authors.lastname: Shimada
mesh_terms: D000818:Animals; D001692:Biological Transport; D002417:Cattle; D018360:Crystallography, X-Ray; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000502:physiology; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D009206:Myocardium / Q000201:enzymology*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000502:physiology; D017494:Proton Pumps / Q000502:physiology; D011522:Protons; D013059:Spectrum Analysis, Raman
chemical_list: D017494:Proton Pumps; D011522:Protons; D003576:Electron Transport Complex IV; D010100:Oxygen