title: Pressure effects on the lateral distribution of cholesterol in lipid bilayers: a time-resolved spectroscopy study.
abstract: The effects of hydrostatic pressure and temperature on the phase behavior and physical properties of the binary mixture palmitoyloleoylphosphatidylcholine/cholesterol, over the 0-40 molar % range of cholesterol compositions, were determined from the changes in the fluorescence lifetime distribution and anisotropy decay parameters of the natural lipid trans-parinaric acid (t-PnA). Pressurized samples were excited with a Ti-sapphire subpicosecond laser, and fluorescence decays were analyzed by the quantified maximum entropy method. Above the transition temperature (T(T) = -5 degrees C), at atmospheric pressure, two liquid-crystalline phases, alpha and beta, are formed in this system. At each temperature and cholesterol concentration below the transition pressure, the fluorescence lifetime distribution pattern of t-PnA was clearly modulated by the pressure changes. Pressure increased the fraction of the liquid-ordered beta-phase and its order parameter, but it decreased the amount of cholesterol in this phase. Palmitoyloleoylphosphatidylcholine/cholesterol phase diagrams were also determined as a function of temperature and hydrostatic pressure.
authors.affiliation: Laboratoire de Biochimie Moléculaire et Cellulaire, CNRS, Université Paris-Sud, Orsay, France.
authors.forename: P
authors.initials: P
authors.lastname: Tauc
authors.forename: C R
authors.initials: CR
authors.lastname: Mateo
authors.forename: J C
authors.initials: JC
authors.lastname: Brochon
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D002784:Cholesterol / Q000737:chemistry*; D005231:Fatty Acids, Unsaturated; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes; D006874:Hydrostatic Pressure; D008051:Lipid Bilayers / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry; D013696:Temperature
chemical_list: D005231:Fatty Acids, Unsaturated; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D002784:Cholesterol; C013641:parinaric acid; C028694:1-palmitoyl-2-oleoylphosphatidylcholine