title: Phase Diagrams and Ordering in Charged Membranes: Binary Mixtures of Charged and Neutral Lipids.
abstract: We propose a model describing the phase behavior of two-component membranes consisting of binary mixtures of electrically charged and neutral lipids. We take into account the structural phase transition (main-transition) of the hydrocarbon chains, and investigate the interplay between this phase transition and the lateral phase separation. The presence of charged lipids significantly affects the phase behavior of the multicomponent membrane. Due to the conservation of lipid molecular volume, the main-transition temperature of charged lipids is lower than that of neutral ones. Furthermore, as compared with binary mixtures of neutral lipids, the membrane phase separation in binary mixtures of charged lipids is suppressed, in accord with recent experiments. We distinguish between two types of charged membranes: mixtures of charged saturated lipid/neutral unsaturated lipid and a second case of mixtures of neutral saturated lipid/charged unsaturated lipid. The corresponding phase behavior is calculated and shown to be very different. Finally, we discuss the effect of added salt on the phase separation and the temperature dependence of the lipid molecular area.
authors.affiliation: School of Materials Science, Japan Advanced Institute of Science and Technology , Ishikawa 923-1292, Japan.
authors.forename: Naofumi
authors.initials: N
authors.lastname: Shimokawa
authors.affiliation: Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Kagawa 761-0395, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Himeno
authors.affiliation: School of Materials Science, Japan Advanced Institute of Science and Technology , Ishikawa 923-1292, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Hamada
authors.affiliation: School of Materials Science, Japan Advanced Institute of Science and Technology , Ishikawa 923-1292, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takagi
authors.affiliation: Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University , Tokyo 192-0397, Japan.
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Komura
authors.affiliation: School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University , Ramat Aviv 69978, Tel Aviv, Israel.
authors.forename: David
authors.initials: D
authors.lastname: Andelman
mesh_terms: D058635:Lipid-Linked Proteins / Q000737:chemistry* / Q000378:metabolism; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D012492:Salts / Q000737:chemistry; D055672:Static Electricity; D013696:Temperature
chemical_list: D058635:Lipid-Linked Proteins; D008563:Membrane Lipids; D012492:Salts