title: Cholesterol Partition and Condensing Effect in Phase-Separated Ternary Mixture Lipid Multilayers.
abstract: The cholesterol partitioning and condensing effect in the liquid-ordered (Lo) and liquid-disordered (Ld) phases were systematically investigated for ternary mixture lipid multilayers consisting of 1:1 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/1,2-dioleoyl-sn-glycero-3-phosphocholine with varying concentrations of cholesterol. X-ray lamellar diffraction was used to deduce the electron density profiles of each phase. The cholesterol concentration in each phase was quantified by fitting of the electron density profiles with a newly invented basic lipid profile scaling method that minimizes the number of fitting parameters. The obtained cholesterol concentration in each phase versus total cholesterol concentration in the sample increases linearly for both phases. The condensing effect of cholesterol in ternary lipid mixtures was evaluated in terms of phosphate-to-phosphate distances, which together with the estimated cholesterol concentration in each phase was converted into an average area per molecule. In addition, the cholesterol position was determined to a precision of (±0.7Å) and an increase of disorder in the lipid packing in the Lo phase was observed for total cholesterol concentration of 20∼30%.
authors.affiliation: Department of Physics, University of California-San Diego, La Jolla, California.
authors.forename: Yicong
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Department of Physics, University of California-San Diego, La Jolla, California.
authors.forename: Sajal K
authors.initials: SK
authors.lastname: Ghosh
authors.affiliation: Department of Physics, University of California-San Diego, La Jolla, California.
authors.forename: David A
authors.initials: DA
authors.lastname: DiLena
authors.affiliation: Department of Physics, University of California-San Diego, La Jolla, California.
authors.forename: Sambhunath
authors.initials: S
authors.lastname: Bera
authors.affiliation: Department of Physics, Northern Illinois University, DeKalb, Illinois.
authors.forename: Laurence B
authors.initials: LB
authors.lastname: Lurio
authors.affiliation: Department of Biomedical Engineering and Department of Chemical Engineering and Materials Science, University of California-Davis, Davis, California.
authors.forename: Atul N
authors.initials: AN
authors.lastname: Parikh
authors.affiliation: Department of Physics, University of California-San Diego, La Jolla, California. Electronic address: ssinha@physics.ucsd.edu.
authors.forename: Sunil K
authors.initials: SK
authors.lastname: Sinha
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D002784:Cholesterol / Q000378:metabolism*; D006813:Humidity; D008051:Lipid Bilayers / Q000737:chemistry*; D044367:Phase Transition; D010710:Phosphates / Q000737:chemistry; D055672:Static Electricity; D014961:X-Ray Diffraction
chemical_list: D008051:Lipid Bilayers; D010710:Phosphates; D015060:1,2-Dipalmitoylphosphatidylcholine; D002784:Cholesterol