title: Cytochrome P-450 rotamers control mixed-function oxygenation in reconstituted membranes. Rotational diffusion studied by delayed fluorescence depolarization.
abstract: 1. Rotational diffusion of purified rabbit-liver microsomal cytochrome P-450 LM2 in reconstituted lipid-vesicle membranes was investigated by measurement of time-dependent polarized emission of delayed fluorescence. 2. Cytochrome P-450 labelled with diiodofluorescein iodoacetamide exhibited strict uniaxial rotation about the normal to the membrane. 3. Benzphetamine retards rotation, while reduction of the cytochrome P-450 substrate-complex accelerates rotation. 4. A model is proposed in which cytochrome P-450 forms disc-shaped rotamers immersed in the bilayer membrane to a depth which is varied by substrate-induced and redox state-dependent conformational changes. The model describes a regulating mechanism of the electron transfer-controlling mixed-function oxygenation.
mesh_terms: D000818:Animals; D001589:Benzphetamine / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004058:Diffusion; D004227:Dithionite / Q000378:metabolism; D005454:Fluorescence Polarization; D007425:Intracellular Membranes / Q000201:enzymology*; D008297:Male; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism*; D011817:Rabbits; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D001589:Benzphetamine; D004227:Dithionite; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases