title: Cholesteryl ester diffusion, location and self-association constraints determine CETP activity with discoidal HDL: excimer probe study.
abstract: The transfer of cholesteryl ester by recombinant cholesteryl ester transfer protein (CETP) between reconstituted discoidal high-density lipoprotein (rHDL) was studied. Particles contained apolipoprotein A-I, unsaturated POPC or saturated DPPC and cholesteryl ester as cholesteryl 1-pyrenedecanoate (CPD) or cholesteryl laurate (CL) in donor and acceptor rHDL, respectively. Probe dynamics fulfilled the quenching sphere-of-action model. The cholesteryl ester exchange between donor and acceptor particles was characterized by a heterogeneous kinetics; the fast exchanging CPD pool was much higher in a case of POPC compared to DPPC complexes. Probe fraction accessible to CETP increased with temperature, suggesting a more homogeneous probe distribution. Noncompetitive inhibition of probe transfer by acceptor particles was observed. The values of Vmax (0.063μMmin(-1)) and catalytic rate constant kcat (0.42s(-1)) together with a similarity of Km (0.9μM CPD) and KI (2.8μM CL) values for POPC-containing rHDL suggest the efficient cholesteryl ester transfer between nascent HDL with unsaturated phosphatidylcholine in vivo. The phospholipid matrix in discoidal HDL may underlie CETP activity through the self-association, diffusivity and location of cholesteryl ester in the bilayer, the accessibility of cholesteryl ester to cholesterol-binding site in apoA-I structure and the binding of cholesteryl ester, positionable by apoA-I, to CETP.
authors.affiliation: National Research Centre for Preventive Medicine, 10, Petroverigsky Street, 101990 Moscow, Russia. Electronic address: dergunov@img.ras.ru.
authors.forename: Alexander D
authors.initials: AD
authors.lastname: Dergunov
authors.affiliation: National Research Centre for Preventive Medicine, 10, Petroverigsky Street, 101990 Moscow, Russia.
authors.forename: Elena V
authors.initials: EV
authors.lastname: Shabrova
authors.affiliation: Research Institute for Physical Chemical Medicine, 119828 Moscow, Russia.
authors.forename: Gennady E
authors.initials: GE
authors.lastname: Dobretsov
mesh_terms: D016632:Apolipoprotein A-I / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D053480:Cholesterol Ester Transfer Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002788:Cholesterol Esters / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008074:Lipoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008075:Lipoproteins, HDL / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D016632:Apolipoprotein A-I; C506642:CETP protein, human; D053480:Cholesterol Ester Transfer Proteins; D002788:Cholesterol Esters; D008074:Lipoproteins; D008075:Lipoproteins, HDL; D010713:Phosphatidylcholines; D011994:Recombinant Proteins; C034366:discoidal lipoproteins; C028694:1-palmitoyl-2-oleoylphosphatidylcholine
keywords: Apolipoprotein A-I; CETP and reverse cholesterol transport; Cholesteryl ester; Discoidal HDL; Enzyme kinetics; Excimer