title: Effect of encapsulated Ca2+ on the surface properties of curved phosphatidylcholine bilayers.
abstract: In this paper, the influence of Ca2+ on the adsorption properties of 1,8-anilinonaphthalenesulfonate (ANS) and analogous probes to sonicated vesicles of phosphatidylcholine was studied by means of spectrofluorometry. The fluorescence of ANS added to the vesicle dispersion increases with the Ca2+ concentration in the inner media but remains constant when Ca2+ concentration is changed in the outside solution. However, the fluorescence decreases when large anions such as ClO4- are present in the external solution. Ca2+ inside large liposomes promotes a similar behaviour to that found in sonicated vesicles when they are osmotically contracted in hypertonic media. The results can be interpreted in terms of Ca2+ adsorption on the inner interface and a cooperative interaction between the monolayers.
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina.
authors.forename: L S
authors.initials: LS
authors.lastname: Bakás
authors.forename: E A
authors.initials: EA
authors.lastname: Disalvo
mesh_terms: D000327:Adsorption; D000817:Anilino Naphthalenesulfonates; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D002704:Chlorates / Q000494:pharmacology; D005456:Fluorescent Dyes; D008051:Lipid Bilayers / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism*; D009282:Naphthalenesulfonates; D010713:Phosphatidylcholines / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D013499:Surface Properties
chemical_list: D000817:Anilino Naphthalenesulfonates; D002704:Chlorates; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D008081:Liposomes; D009282:Naphthalenesulfonates; D010713:Phosphatidylcholines; C027132:1-anilino-8-naphthalenesulfonate; C009497:2-(4-toluidino)-6-naphthalenesulfonic acid; D012964:Sodium; D002118:Calcium