pH Effect of the sphingomyelin membrane interfacial tension.
The effect of pH on the interfacial tension of a sphingomyelin membrane in aqueous solution has been studied. Three models describing H(+) and OH(-) ion adsorption on the bilayer lipid surface are presented. In models I and II, the membrane surface is continuous, with uniformly distributed functional groups as centers of H(+) and OH(-) ion adsorption. In model III, the membrane surface is composed of lipid molecules, with and without adsorbed H(+) and OH(-) ions. The contribution of each individual lipid molecule to the overall interfacial tension of the bilayer was assumed to be additive in models I and II. In model III, the Gibbs isotherm was used to describe adsorption of H(+) and OH(-) ions at the bilayer surface. Theoretical equations are derived to describe the interfacial tension as a function of pH for all three models. Maximum interfacial tension was observed experimentally at the isoelectric point.
Petelska
Aneta Dorota
AD
Institute of Chemistry, University of Bialystok, Bialystok, Poland.
Figaszewski
Zbigniew Artur
ZA
D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D008051:Lipid Bilayers / Q000737:chemistry*; D008560:Membrane Fluidity; D008956:Models, Chemical; D013109:Sphingomyelins / Q000737:chemistry*; D013500:Surface Tension
D008051:Lipid Bilayers; D013109:Sphingomyelins