title: Single crystals of bovine heart cytochrome c oxidase at fully oxidized resting, fully reduced and CO-bound fully reduced states are isomorphous with each other.
abstract: Fully reduced and CO-bound fully reduced forms of cytochrome c oxidase from beef heart muscle were crystallized in the presence of sodium ascorbate under N2 or CO atmosphere. Hexagonal bipyramidal and tetragonal crystals were obtained for both forms depending on buffer species. The hexagonal bipyramidal crystals, as large as 0.6 mm in the largest dimension, diffracted X-rays at 7 A resolution, showing an identical space group and cell dimension, P6(2) or P6(4) and a = b = 209 A, c = 283 A, respectively. These parameters coincide with those for crystals of the fully oxidized resting enzyme. This result suggests that a large conformational change, like a subunit arrangement, is not induced by the redox change and/or binding of CO (and possibly O2) to heme a3.
authors.affiliation: Department of Life Science, Himeji Institute of Technology, Hyogo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Shinzawa-Itoh
authors.forename: H
authors.initials: H
authors.lastname: Yamashita
authors.forename: S
authors.initials: S
authors.lastname: Yoshikawa
authors.forename: Y
authors.initials: Y
authors.lastname: Fukumoto
authors.forename: T
authors.initials: T
authors.lastname: Abe
authors.forename: T
authors.initials: T
authors.lastname: Tsukihara
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D002248:Carbon Monoxide / Q000737:chemistry / Q000378:metabolism; D002417:Cattle; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology*; D010084:Oxidation-Reduction; D011487:Protein Conformation; D014961:X-Ray Diffraction
chemical_list: D002248:Carbon Monoxide; D003576:Electron Transport Complex IV