title: Distinguishing between Cl- and O2(2-) as the bridging element between Fe3+ and Cu2+ in resting-oxidized cytochrome c oxidase.
abstract: Fully oxidized cytochrome c oxidase (CcO) under enzymatic turnover is capable of pumping protons, while fully oxidized CcO as isolated is not able to do so upon one-electron reduction. The functional difference is expected to be a consequence of structural differences: [Fe(3+)-OH(-)] under enzymatic turnover versus [Fe(3+)-O(2)(2-)-Cu(2+)] for the as-isolated CcO. However, the electron density for O(2)(2-) is equally assignable to Cl(-). An anomalous dispersion analysis was performed in order to conclusively demonstrate the absence of Cl(-) between the Fe(3+) and Cu(2+). Thus, the peroxide moiety receives electron equivalents from cytochrome c without affecting the oxidation states of the metal sites. The metal-site reduction is coupled to the proton pump.
authors.affiliation: Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: Michihiro
authors.initials: M
authors.lastname: Suga
authors.forename: Naomine
authors.initials: N
authors.lastname: Yano
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Muramoto
authors.forename: Kyoko
authors.initials: K
authors.lastname: Shinzawa-Itoh
authors.forename: Tomoko
authors.initials: T
authors.lastname: Maeda
authors.forename: Eiki
authors.initials: E
authors.lastname: Yamashita
authors.forename: Tomitake
authors.initials: T
authors.lastname: Tsukihara
authors.forename: Shinya
authors.initials: S
authors.lastname: Yoshikawa
mesh_terms: D002713:Chlorine / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D003576:Electron Transport Complex IV / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D054730:Protein Interaction Domains and Motifs
chemical_list: D002713:Chlorine; D003300:Copper; D007501:Iron; D003576:Electron Transport Complex IV; D010100:Oxygen