title: Resonance Raman spectroscopy of cytochrome oxidase using Soret excitation: selective enhancement, indicator bands, and structural significance for cytochromes a and a3.
abstract: Resonance Raman studies of oxidized and reduced cytochrome oxidase and liganded derivatives of the oxidized enzyme have been performed by using direct-Soret excitation at 413.1 and 406.7 nm, as well as near-Soret excitation (457.9 nm) and alpha-band excitation (604.6 nm). The Soret results clearly show selective enhancement of Raman modes of the hemes of cytochromes a and a3, depending upon the excitation wavelength chosen. For the preparations employed in this study, photoreduction of cytochrome oxidase in the laser beam was not a significant problem. Resonance Raman frequencies sensitive to oxidation state and spin state or core expansion of the a and a3 hemes are identified and correlated with those previously identified for other heme proteins. An unusual low-frequency (less than 500 cm(-1)) spectrum is observed for oxidized high-spin cytochrome a3, which may be due to axial nonheme structures in this cytochrome.
mesh_terms: D000818:Animals; D002417:Cattle; D017936:Cytochrome a Group; D003580:Cytochromes / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000378:metabolism*; D004910:Erythrocyte Membrane; D009206:Myocardium / Q000201:enzymology; D010084:Oxidation-Reduction; D013053:Spectrophotometry; D013059:Spectrum Analysis, Raman
chemical_list: D017936:Cytochrome a Group; D003580:Cytochromes; D003576:Electron Transport Complex IV