Resonance Raman spectra for catalytic intermediates of cytochrome c oxidase detected with a mixed flow transient apparatus.

A novel technique was employed to collect resonance Raman spectra of an oxygenated intermediate of cytochrome c oxidase. Instead of laser pulses of high peak power, which may cause photodissociation, a continuous wave laser and a mixed flow apparatus were used. An intermediate formed within 450 microseconds after the reaction of cytochrome c oxidase with molecular oxygen could be detected. From the spectra it could be deduced that the most likely candidate for the intermediate would be a transient oxygenated species having the Fe2+ - O2 or Fe4+ = O heme in cytochrome a3 and the Fe2+ heme in cytochrome a.