title: Zwitterionic detergent mediated interaction of purified cytochrome P-450LM4 from 5,6-benzoflavone-treated rabbits with MADPH-cytochrome P-450 reductase.
abstract: Hydroxylation of acetanilide catalyzed by purified cytochrome P-450LM4 and NADPH-cytochrome P-450 reductase was reconstituted with the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS). The optimum rate of production of 4-hydroxyacetanilide was observed between 3 and 7 mM CHAPS and was about half that with 0.05 mM dilauroylglyceryl-3-phosphocholine (di-12-GPC). At higher detergent concentrations, hydroxylase activity decreased until at 15-20 mM CHAPS the system was inactive. The effect of CHAPS on the state of aggregation of P-450LM4 and on interaction between the cytochrome and P-450 reductase alone and under turnover conditions was investigated by ultracentrifugation. At 4 mM CHAPS, P-450LM4 was hexameric to heptameric (Mr 369,000). Neither reductase nor reductase plus acetanilide and NADPH altered the state of P-450LM4 aggregation, suggesting that a stable 1:1 P-450/reductase complex did not form under turnover conditions. Replacing CHAPS with 0.05 mM di-12-GPC resulted in formation of heterogeneous P-450 oligomers (Mr greater than 480,000). At CHAPS concentrations where substrate hydroxylation did not occur (15 and 22 mM), P-450LM4 was shown by sedimentation equilibrium measurements to be dimeric and monomeric, respectively. P-450 reductase was shown to reduce monomeric P-450LM4 in the presence of NADPH. Thus, the dependence of hydroxylase activity on [CHAPS] may be related to the state of aggregation of the cytochrome. An apparent correlation between P-450 aggregation state and NADPH-supported hydroxylation was also observed with phenobarbital-inducible P-450LM2 in the presence of detergents [Dean, W.L., & Gray, R.D. (1982) J. Biol. Chem. 257, 14679-14685; Wagner, S.L., Dean, W.L., & Gray, R.D. (1984) J. Biol. Chem. 259, 2390-2395].
mesh_terms: D000818:Animals; D001571:Benzoflavones / Q000494:pharmacology*; D002793:Cholic Acids / Q000494:pharmacology*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D003902:Detergents / Q000494:pharmacology*; D005419:Flavonoids / Q000494:pharmacology*; D007700:Kinetics; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism*; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000494:pharmacology*; D011817:Rabbits; D013501:Surface-Active Agents / Q000494:pharmacology*; D019324:beta-Naphthoflavone
chemical_list: D001571:Benzoflavones; D002793:Cholic Acids; D003902:Detergents; D005419:Flavonoids; D010713:Phosphatidylcholines; D013501:Surface-Active Agents; C015153:1,2-dilauroylphosphatidylcholine; D019324:beta-Naphthoflavone; D003577:Cytochrome P-450 Enzyme System; D009251:NADPH-Ferrihemoprotein Reductase; C028213:3-((3-cholamidopropyl)dimethylammonium)-1-propanesulfonate