Chemical and spectroscopic evidence for the formation of a ferryl Fea3 intermediate during turnover of cytochrome c oxidase.
When partially reduced cytochrome c oxidase samples are reoxidized with dioxygen, an EPR-silent dioxygen intermediate, which is at the three-electron level of dioxygen reduction, is trapped at the dioxygen reduction site. The intermediate has novel spectral features at 580 and 537 nm. Combined optical and EPR results reveal that this intermediate reacts rapidly with CO at 277-298 K causing the abolition of the 580/537 mm features and the appearance of a rhombic CuB EPR signal. A ferryl Fea3, or an intermediate at the same formal level of oxidation, is proposed to oxidize CO to CO2 producing an EPR-detectable CuB adjacent to a low-spin ferrous Fea3-dioxygen (or carbon monoxide) adduct.
D000818:Animals; D002248:Carbon Monoxide; D002417:Cattle; D004578:Electron Spin Resonance Spectroscopy; D003576:Electron Transport Complex IV / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D008956:Models, Chemical; D009206:Myocardium / Q000201:enzymology; D010084:Oxidation-Reduction
D002248:Carbon Monoxide; D007501:Iron; D003576:Electron Transport Complex IV