title: Stabilization of sphingomyelin interactions by interfacial hydroxyls - a study of phytosphingomyelin properties.
abstract: D-ribo-phytosphingosines are biologically significant long-chain bases present in various sphingolipids from yeasts, fungi, plants and mammals. In this study we prepared phytopalmitoylsphingomyelin (phytoPSM) analogs based on the D-ribo-phytosphingosine base. The N-linked acyl chains were either 16:0, 2OH(R)16:0 (natural isomer), or 2OH(S)16:0. The gel-phase of phytoPSM was more stable than that of PSM (T(m) 48.6°C and 41.0°C, respectively). The gel-liquid crystalline phase transition enthalpies were 9.1±0.4 and 6.1±0.3kcal/mol for phytoPSM and PSM, respectively. An N-linked 2OH(R)16:0 in phytoPSM destabilized the gel phase relative to phytoPSM (by ~+6°C, based on DPH anisotropy measurements), whereas 2OH(S)16:0 in phytoPSM stabilized it (by ~-6°C). All phytoPSM analogs formed sterol-enriched ordered domains in a fluid ternary bilayer, and those containing phytoPSM or 2OH(S)phytoPSM were more thermostable than the domains containing 2OH(R)phytoPSM or PSM. The affinity of cholestatrienol for POPC bilayers containing 20mol% phytoPSM was higher than for comparable bilayers with an equal amount of PSM. The 2-hydroxylated acyl chains in phytoPSM did not markedly alter sterol affinity. We conclude that phytoPSM is a more ordered sphingolipid than PSM, and is fully capable of interacting with cholesterol.
authors.affiliation: Biochemistry, Department of Biosciences, Åbo Akademi University, Tykistökatu 6A, 20520 Turku, Finland.
authors.forename: Shishir
authors.initials: S
authors.lastname: Jaikishan
authors.forename: J Peter
authors.initials: JP
authors.lastname: Slotte
mesh_terms: D015081:2-Naphthylamine / Q000031:analogs & derivatives / Q000737:chemistry; D016880:Anisotropy; D001703:Biophysics / Q000379:methods; D002152:Calorimetry, Differential Scanning / Q000379:methods; D002784:Cholesterol / Q000737:chemistry; D003505:Cyclodextrins / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D006860:Hydrogen Bonding; D007700:Kinetics; D007848:Laurates / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods; D013107:Sphingolipids / Q000737:chemistry; D013109:Sphingomyelins / Q000737:chemistry*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000737:chemistry; D013261:Sterols / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics
chemical_list: D003505:Cyclodextrins; C521790:D-ribo-phytosphingosine; D007848:Laurates; D008051:Lipid Bilayers; D008081:Liposomes; D013107:Sphingolipids; D013109:Sphingomyelins; D013261:Sterols; D002784:Cholesterol; D015081:2-Naphthylamine; D013110:Sphingosine; C065580:laurdan