title: Effect of n-alkanes on lipid bilayers depending on headgroups.
abstract: Phase behavior and structural properties were examined for phospholipid bilayers having different headgroups (DMPC, DMPS and DMPE) with added n-alkanes to study effect of flexible additives. Change in the temperatures of main transition of the lipid/alkane mixtures against the length of added alkanes depends largely on the headgroup. Theoretical analysis of the change of the temperature of transition indicates that the headgroup dependence is dominantly originated in the strong dependence of total enthalpy on the headgroups. The results of X-ray diffraction show that the enthalpic stabilization due to enhanced packing of acyl chains of the lipid by alkanes in the gel phase causes the headgroup-dependent change in the phase transition behavior. The enhanced packing in the gel phase also leads to easy emergence of the subgel phase with very short relaxation time at room temperature in the DMPE-based bilayers.
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: Asami
authors.initials: A
authors.lastname: Endo
authors.affiliation: Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
authors.forename: Koyomi
authors.initials: K
authors.lastname: Nakazawa
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. Electronic address: kazuya@chem.tsukuba.ac.jp.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Saito
mesh_terms: D000473:Alkanes / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008968:Molecular Conformation; D044367:Phase Transition; D010743:Phospholipids / Q000737:chemistry*; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D000473:Alkanes; D008051:Lipid Bilayers; D010743:Phospholipids
keywords: Head group dependence; Lipid packing; Phase transition; Phospholipid; n-Alkane