The identity of a new copper(II) electron paramagnetic resonance signal in cytochrome c oxidase.
In reoxidation experiments with cytochrome c oxidase (EC 1.9.3.1) in the presence of both reducing substrate and molecular oxygen, a new EPR signal from Cu2+ has been observed. The new signal corresponds to 0.45 Cu per functional unit. It is concluded that the new EPR signal originates from CuB2+, the copper which is EPR-nondetectable in the resting enzyme. Optical absorption changes in the 500-700 nm region accompanies the decay of the new Cu2+ EPR signal. Based on the results in this investigation a catalytic cycle for cytochrome oxidase is proposed.
D000818:Animals; D002417:Cattle; D003300:Copper; D004578:Electron Spin Resonance Spectroscopy; D003576:Electron Transport Complex IV; D010084:Oxidation-Reduction
D003300:Copper; D003576:Electron Transport Complex IV