title: Cytochrome a3 structure in carbon monoxide-bound cytochrome oxidase.
abstract: The iron-carbon monoxide stretching mode and the iron-carbon-oxygen bending mode in carbon monoxide-bound cytochrome oxidase have been assigned at 520 and 578 cm-1, respectively. The frequencies, widths, and intensities of these modes show that the Fe-C-O grouping in carbon monoxide-cytochrome a3 is linear but tilted from the normal to the heme plane; that the iron-histidine bond in both five- and six-coordinate cytochrome a3 is strained; and that the carbon monoxide and the proximal histidine each have characteristic, well-defined orientations in all molecules. These data can account for the binding affinities of carbon monoxide and dioxygen under physiological conditions.
mesh_terms: D000818:Animals; D002248:Carbon Monoxide / Q000378:metabolism; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D003576:Electron Transport Complex IV / Q000378:metabolism*; D009211:Myoglobin / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D013059:Spectrum Analysis, Raman
chemical_list: D009211:Myoglobin; D002248:Carbon Monoxide; D003576:Electron Transport Complex IV; D010100:Oxygen