title: Resonance Raman spectra of bovine adrenal cytochrome P-450SCC.
abstract: Resonance Raman spectra were observed for a mitochondria-type cytochrome p-450 (P-450SCC) for the first time. Reduced P-450SCC at pH 7.4 exhibited the V4 line at 1342 cm-1, which is an unusually low frequency compared with an ordinary protohemoprotein but is common to the family of cytochrome P-450, suggesting the coordination of a strong pi-donor such as thiolate anion at the fifth coordination position of the heme iron. The anomaly was preserved for the CO-complex of the reduced form. The V10 line of oxidized P-450SCC with a substrate was observed at 1617 cm-1. This frequency and those of other structure-sensitive bands implied that the heme iron of oxidized P-450SCC adopts the hexa-coordinate high-spin structure, in contrast with the high-spin type cytochrome P-450 purified from phenobarbital- or 3-methylcholanthrene-treated rabbit liver microsomes which presumably have a penta-coordinate structure. In the presence of 20alpha-hydroxycholesterol, oxidized P-450SCC gave the V10 line at 1637 cm-1, i.e., at a frequency similar to that of low-spin type cytochrome P-450. The alkaline-denatured P-420SCC preparation in the presence of both dithiothreitol and EDTA, but not the P-450SCC gave the V10 line at 1637 cm-1, i.e., at a frequency similar to that of low-spin type cytochrome P-450. The alkaline-denatured P-420SCC preparation in the presence of both dithiothreitol and EDTA, but not the P-450SCC.
mesh_terms: D000302:Adrenal Cortex / Q000201:enzymology*; D000818:Animals; D002417:Cattle; D003577:Cytochrome P-450 Enzyme System / Q000528:radiation effects; D006888:Hydroxycholesterols / Q000494:pharmacology; D007834:Lasers; D008928:Mitochondria / Q000201:enzymology*; D010084:Oxidation-Reduction; D013059:Spectrum Analysis, Raman; D013696:Temperature
chemical_list: D006888:Hydroxycholesterols; C025813:20-hydroxycholesterol; D003577:Cytochrome P-450 Enzyme System