title: Contrasting Effects of a Rigid Core and an Alkyl Chain in nCB on the Phase Behavior of Lipid Bilayers.
abstract: Molecules incorporated into biomembranes often bear both a core and an alkyl chain in a single molecule (e.g., sterols). To clarify the effects of these two parts of a molecule, the phase behavior of a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayer containing 4-n-alkyl-4'-cyanobiphenyl (nCB) (n = 0-8) was investigated. The trends of the main transition temperature (Tm) with respect to n and of the pretransition temperature (Tp) with respect to nCB content changed at n = 3. It was therefore suggested that the two parts of the molecule had opposing effects on the phase behavior of DPPC bilayers. The core appears to perturb molecular ordering in the gel phase and lowers Tm (like cholesterol), while alkyl chains appear to order the lipids in the gel phase and raise Tm (like n-alkanes). In addition, Tm exhibits the so-called odd-even effect based on the alkyl chain length of the minor component, nCB. Depending on the value of n, the variation in Tp was dependent on the additive content, although the pretransition was rarely observed at high contents.
authors.affiliation: Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba , Tsukuba, Ibaraki 305-8571, Japan.
authors.forename: Hatsuho
authors.initials: H
authors.lastname: Usuda
authors.affiliation: Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba , Tsukuba, Ibaraki 305-8571, Japan.
authors.forename: Mafumi
authors.initials: M
authors.lastname: Hishida
authors.affiliation: Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba , Tsukuba, Ibaraki 305-8571, Japan.
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Yamamura
authors.affiliation: Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba , Tsukuba, Ibaraki 305-8571, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Saito
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000031:analogs & derivatives* / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*
chemical_list: D008051:Lipid Bilayers; D010636:Phenols; D015060:1,2-Dipalmitoylphosphatidylcholine; C081581:colfosceril palmitate