title: Salt effects on lamellar repeat distance depending on head groups of neutrally charged lipids.
abstract: Change in lamellar repeat distances of neutrally charged lipids upon addition of monovalent salts was measured with small-angle X-ray scattering for combinations of two lipids (PC and PE lipids) and six salts. Large dependence on lipid head group is observed in addition to those on added cation and anion. The ion and lipid dependences have little correlation with measured surface potentials of lipid membranes. These results indicate that the lamellar swelling by salt is not explained through balance among interactions considered previously (van der Waals interaction, electrostatic repulsion emerged by ion binding, etc.). It is suggested that effect of water structure, which is affected by not only ions but also lipid itself, should be taken into account for understanding membrane-membrane interactions, as in the Hofmeister effect.
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.forename: Yasuhisa
authors.initials: Y
authors.lastname: Yamamura
authors.forename: Kazuya
authors.initials: K
authors.lastname: Saito
mesh_terms: D005997:Glycerylphosphorylcholine / Q000737:chemistry; D008055:Lipids / Q000737:chemistry*; D010714:Phosphatidylethanolamines / Q000737:chemistry; D012492:Salts / Q000737:chemistry*
chemical_list: D008055:Lipids; D010714:Phosphatidylethanolamines; D012492:Salts; D005997:Glycerylphosphorylcholine