title: Infrared and Raman spectroscopic investigation of the reaction mechanism of cytochrome c oxidase.
abstract: Recent progress in studies on the proton-pumping and O₂reduction mechanisms of cytochrome c oxidase (CcO) elucidated by infrared (IR) and resonance Raman (rR) spectroscopy, is reviewed. CcO is the terminal enzyme of the respiratory chain and its O₂reduction reaction is coupled with H⁺ pumping activity across the inner mitochondrial membrane. The former is catalyzed by heme a3 and its mechanism has been determined using a rR technique, while the latter used the protein moiety and has been investigated with an IR technique. The number of H⁺ relative to e⁻ transferred in the reaction is 1:1, and their coupling is presumably performed by heme a and nearby residues. To perform this function, different parts of the protein need to cooperate with each other spontaneously and sequentially. It is the purpose of this article to describe the structural details on the coupling on the basis of the vibrational spectra of certain specified residues and chromophores involved in the reaction. Recent developments in time-resolved IR and Raman technology concomitant with protein manipulation methods have yielded profound insights into such structural changes. In particular, the new IR techniques that yielded the breakthrough are reviewed and assessed in detail. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.
authors.affiliation: Picobiology Institute, Graduate School of Life Science, University of Hyogo, RSC-UH Leading Program Center, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Nakashima
authors.affiliation: Picobiology Institute, Graduate School of Life Science, University of Hyogo, RSC-UH Leading Program Center, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan; Department of Life Science, Graduate School of Life Science, University of Hyogo, RSC-UH Leading Program Center, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ogura
authors.affiliation: Picobiology Institute, Graduate School of Life Science, University of Hyogo, RSC-UH Leading Program Center, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan. Electronic address: teizo@sci.u-hyogo.ac.jp.
authors.forename: Teizo
authors.initials: T
authors.lastname: Kitagawa
mesh_terms: D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D017494:Proton Pumps / Q000737:chemistry / Q000378:metabolism; D011522:Protons; D013055:Spectrophotometry, Infrared / Q000379:methods; D013059:Spectrum Analysis, Raman / Q000379:methods
chemical_list: D017494:Proton Pumps; D011522:Protons; D003576:Electron Transport Complex IV; D010100:Oxygen
keywords: Cytochrome c oxidase; Proton-pumping mechanism; Time-resolved infrared and Raman spectroscopy