Resonance Raman spectra of CN(-) -bound cytochrome oxidase: Spectral isolation of a(+2), a(3)(+2) and a(3)(+2)(CN(-)).

01 January 1985

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In contrast to prior reports, reduced cyanide-bound cytochrome oxidase in the absence of any oxygen gives a resonance Raman spectrum consistent with that expected for low spin heme a. Thus, ligand binding of cytochrome a3 to form a six coordinate low spin ferrous heme does not result in any unusual electronic structure, hydrogen bonding, environment, or conformation of the formyl group. It appears unlikely that there are any changes in this group in cytochrome a3 which control the ligand affinity or redox potential in physiological forms of the ferrous enzyme.