title: The effect of dilauroyl-L-3-phosphatidylcholine on the interaction between cytochrome P-450 1A1 and benzo[a]pyrene.
abstract: Fluorescence quenching of benzo[a]pyrene (BP) by cytochrome P-450 1A1 was used to probe the effect of the lipid, dilauroyl-L-3-phosphatidylcholine, on this substrate-enzyme interaction. In the presence of lipid, a monoclonal antibody to this P-450 maximally inhibited BP binding at an antibody-to-P-450 ratio of 1:2, corresponding to an antibody crosslinked P-450 complex. The antibody did not inhibit BP binding in the absence of lipid. These results indicate that when P-450 is subjected to the orientational constraints imposed by antibody-mediated crosslinking, the lipid alters the conformation or quaternary structure of the P-450 oligomer in a manner which changes its affinity for BP.
authors.affiliation: Laboratory of Molecular Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
authors.forename: Y
authors.initials: Y
authors.lastname: Omata
authors.forename: F K
authors.initials: FK
authors.lastname: Friedman
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001564:Benzo(a)pyrene / Q000378:metabolism*; D001667:Binding, Competitive; D003577:Cytochrome P-450 Enzyme System / Q000276:immunology / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000494:pharmacology*; D051381:Rats
chemical_list: D000911:Antibodies, Monoclonal; D010713:Phosphatidylcholines; C015153:1,2-dilauroylphosphatidylcholine; D001564:Benzo(a)pyrene; D003577:Cytochrome P-450 Enzyme System