Evidence for the absence of photoreduction of the metal centers of cytochrome C oxidase by X-irradiation.
Samples of X-irradiated cytochrome c oxidase were examined by electron paramagnetic resonance and optical spectroscopy. Both radiation from the Stanford Synchrotron Radiation Laboratory and a conventional X-ray source (W target) were utilized. The X-ray flux from these sources ranges from 10(9) to 10(13) photons/s. No evidence was found for photoreduction of the metal centers in the enzyme by X-ray photons. These results demonstrate that the integrity of cytochrome c oxidase is maintained using the conditions under which X-ray absorption measurements are presently being made.
D000818:Animals; D002417:Cattle; D003300:Copper; D004578:Electron Spin Resonance Spectroscopy; D003576:Electron Transport Complex IV / Q000378:metabolism* / Q000528:radiation effects; D007501:Iron; D010084:Oxidation-Reduction; D010315:Particle Accelerators; D013057:Spectrum Analysis; D014414:Tungsten
D003300:Copper; D007501:Iron; D003576:Electron Transport Complex IV; D014414:Tungsten