title: Involvement of nonlamellar-prone lipids in the stability increase of human cytochrome P450 1A2 in reconstituted membranes.
abstract: The effect of nonlamellar-prone lipids, diacylglycerol (DG) and phosphatidylethanolamine (PE), on the stability of human cytochrome P450 1A2 (CYP1A2) was examined. When 100% phosphatidylcholine (PC) in standard vesicles was gradually replaced with either DG or PE, the stability of CYP1A2 increased; the incubation time-dependent destruction of spectrally detectable P450, decrease of catalytic activity, reduction of intrinsic fluorescence, and increased sensitivity to trypsin digestion were significantly alleviated. The ternary system of PC/PE/DG increased the stability of CYP1A2 more, even at lower concentrations of each nonlamellar-prone lipid, than that of the binary lipid mixture (PC/nonlamellar lipid). By incorporating the nonlamellar-prone lipids, the CYP1A2-induced increase of the surface pressure of the lipid monolayer was much higher compared to that for 100% PC. Increased surface pressure indicates a deep insertion of the protein into lipid monolayers. Nonlamellar lipids also increased the transition temperature of CYP1A2 in thermal unfolding and reduced the incubation time-dependent detachment of membrane-bound CYP1A2 from vesicles. Taken together, these results suggest that nonlamellar lipids per se and/or the phase properties of the membrane containing these lipids are important in the enhanced stability of CYP1A2 and the concomitant maintenance of catalytic activity of the protein.
authors.affiliation: Department of Biochemistry, College of Veterinary Medicine, Chonnam National University, Gwangju 500-757, Korea. thahn@chonnam.ac.kr
authors.forename: Taeho
authors.initials: T
authors.lastname: Ahn
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Yun
authors.forename: Doo-Byoung
authors.initials: DB
authors.lastname: Oh
mesh_terms: D002248:Carbon Monoxide / Q000378:metabolism; D002384:Catalysis; D019388:Cytochrome P-450 CYP1A2 / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007501:Iron / Q000494:pharmacology; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry; D008567:Membranes, Artificial; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D011489:Protein Denaturation; D017510:Protein Folding; D013057:Spectrum Analysis; D013696:Temperature; D013997:Time Factors
chemical_list: D008055:Lipids; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; C057561:1-palmitoyl-2-oleoylphosphatidylethanolamine; D002248:Carbon Monoxide; D007501:Iron; D019388:Cytochrome P-450 CYP1A2