Swelling of phospholipids by monovalent salt

• DOI: 10.1194/jlr.m500401-jlr200
• Publication Date: 2005-11-03T01:43:52Z
• Authors: Horia I. Petrache; Stephanie Tristra...; Daniel Harries; Norbert Kučerka; John F. Nagle; V. Adrian Parsegian
• Keywords: bending rigidity; Anions; Bromides; Lipid Bilayers; Static Electricity; lipid head group; FOS: Physical sciences; QD415-436; Biochemistry; 03 medical and health sciences; Chlorides; X-Ray Diffraction; Osmotic Pressure; Phospholipids; 0303 health sciences; membrane interactions; Water; 20399 Classical Physics not elsewhere classified; halides; ion binding; Models, Chemical; Liposomes; Phosphatidylcholines; Thermodynamics; Dimyristoylphosphatidylcholine; hydration; Algorithms

Critical to biological processes such as membrane fusion and secretion, ion-lipid interactions at the membrane-water interface still raise many unanswered questions. Using reconstituted phosphatidylcholine membranes, we confirm here that multilamellar vesicles swell in salt solutions, a direct indication modifies between neighboring membranes. By varying sample histories, by comparing with data from ion carrier-containing bilayers, eliminate possibility swelling is an equilibration artifact. Although both attractive repulsive forces could be modified salt, show experimentally driven primarily weakening of van der Waals attraction. To isolate effect on interactions, focus high concentrations which any possible electrostatic are screened. analysis X-ray diffraction data, does not alter structure or bending rigidity, eliminating fluctuation change salt. measuring changes interbilayer separation applied osmotic stress, have determined, using standard paradigm for bilayer 1 M KBr KCl decrease strength 50%. attractions, increases energy barriers contact, possibly affecting cellular communication signaling.