title: Electron paramagnetic resonance studies of the purified cytochrome P-450scc and P-45011beta from bovine adrenocortical mitochondria.
abstract: Electron paramagnetic resonance studies have been carried out on two species of cytochrome P-450 (P-450scc and P-45011beta) purified from bovine adrenocortical mitochondria. The g values of the steroid-bound cytochromes in the high spin form were determined at 4.2 degrees K to be 8.07, 3.60 and 1.70 for P-450scc and 8.00, 3.65 and 1.71 for P-45011beta. The E/D values were estimated to be 0.103 for P-450scc and 0.099 for P-45011beta. Either high spin P-450 was converted into the low spin form by the treatment with an NADPH dependent electron donating system and subsequent gel filtration in order to remove the steroid. The g values of the low spin ferric cytochromes were 2.423, 2.247 and 1.914 for P-450scc and 2.430, 2.251 and 1.919 for P-45011beta at 77 degrees K. The values for magnitude of delta/gamma, magnitude of V/gamma and k were 5.69, 5.21 and 1.11 for P-450scc and 5.94, 5.38 and 1.16 for P-45011beta. These studies indicate that there are some differences in the ferric heme environment between P-450scc and P-45011beta.
mesh_terms: D000302:Adrenal Cortex / Q000201:enzymology*; D000818:Animals; D002417:Cattle; D003577:Cytochrome P-450 Enzyme System / Q000302:isolation & purification; D004578:Electron Spin Resonance Spectroscopy; D006888:Hydroxycholesterols; D008928:Mitochondria / Q000201:enzymology*; D011284:Pregnenolone; D011487:Protein Conformation
chemical_list: D006888:Hydroxycholesterols; D011284:Pregnenolone; D003577:Cytochrome P-450 Enzyme System