title: Oxidation-reduction potential of soluble and membrane-bound rabbit liver microsomal cytochrome P-450 LM2.
abstract: The redox midpoint potentials of rabbit liver microsomal cytochromes P-450 and of soluble and membrane-bound rabbit liver microsomal cytochrome P-450 LM2 were determined using EPR-spectroscopy and absorption difference spectrometry with NADPH or dithionite as reductants. Using EPR, a redox midpoint potential of -0.36 V was obtained both for the low spin and the high spin components of microsomal cytochrome P-450. Spectrophotometrical determinations yielded very similar values: -0.37 V and -0.34 V for the low and high spin signals, respectively. Soluble cytochrome P-450 LM2 had a midpoint potential of -0.32 V. This redox potential was not significantly affected by incorporation of the protein into an artificial membrane structure or, furthermore, by the presence of cytochrome b5 the same membrane.
mesh_terms: D000818:Animals; D003080:Cold Temperature; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004227:Dithionite; D004578:Electron Spin Resonance Spectroscopy; D007425:Intracellular Membranes / Q000201:enzymology; D008862:Microsomes, Liver / Q000201:enzymology*; D009249:NADP; D010084:Oxidation-Reduction; D010634:Phenobarbital / Q000494:pharmacology; D011817:Rabbits; D012995:Solubility
chemical_list: D004227:Dithionite; D009249:NADP; D003577:Cytochrome P-450 Enzyme System; D010634:Phenobarbital