title: X-ray absorption edge studies on oxidized and reduced cytochrome c oxidase.
abstract: The x-ray absorption edge spectra of the Cu and Fe-centers in oxidized and reduced cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase: EC 1.9.3.1) have been obtained using synchrotron radiation from the SPEAR storage ring at the Stanford Linear Accelerator Center. In addition, oxidized and reduced plastocyanin as well as a number of model copper compounds in various oxidation states were also examined. A comparison of the absorption edge fine structure of cytochrome oxidase with those of the models indicates that one of the two coopers in the oxidized protein is in the +1 oxidation state. Upon reduction of the protein with dithionite, the second copper becomes Cu(I). The shift in the Fe K-edge of cytochrome oxidase upon reduction is small (about 2 e V or 3 times 10(-19 J) and is comparable to that previously observed for the reduction of the heme iron of cytochrome c.
mesh_terms: D000818:Animals; D002417:Cattle; D002642:Chick Embryo; D003300:Copper; D003574:Cytochrome c Group; D004285:Dogs; D003576:Electron Transport Complex IV; D007501:Iron; D009206:Myocardium / Q000201:enzymology; D010084:Oxidation-Reduction; D010970:Plastocyanin; D013057:Spectrum Analysis; D014965:X-Rays
chemical_list: D003574:Cytochrome c Group; D003300:Copper; D010970:Plastocyanin; D007501:Iron; D003576:Electron Transport Complex IV