Resonance Raman detection of a v(Fe-CO) stretching frequency in cytochrome P-450scc from bovine adrenocortical mitochondria.

Resonance Raman scattering experiments on CO-complexed cytochrome P-450scc from bovine adrenocortical mitochondria demonstrate the simultaneous enhancement of v(Fe-CO) stretching and bound v(C-O) stretching frequencies at 477 and 1953 cm-1, respectively. These assignments were made on the basis of frequency shifts with the isotope 12C18O. This unusually low v(Fe-CO) stretching frequency in cytochrome P-450scc, compared with other CO-complexed hemoproteins such as CO-hemoglobin and -myoglobin, is presumably due to the thiolate ligation to the heme iron trans to CO and due to the linear and perpendicular configuration of CO binding to the heme.