Surface behaviour of gangliosides and related glycosphingolipids

Abstract

1. The surface behaviour of six different gangliosides and eight chemically related glycosphingolipids was investigated in monolayers at the air-water interface. 2. Mono-, di-, tri and tetra-hexosylceramides had force-area isotherms showing similar limiting molecular areas on 145 mM-NaCl, pH 5.6. The increasing number of negatively charged sialosyl residues in mono-, di- and tri-sialogangliosides induced a progressive increase in the liquid-expanded character of the films and in the limiting area occupied per molecule, owing to electrostatic repulsions. When the ganglioside monolayers were spread on subphases at pH 1.2, the limiting area per molecule was similar to that found for neutral glycosphingolipids. 3. The monolayer collapse pressure at pH 5.6 increased with the number of uncharged carbohydrate units up to when the polar head group contained 3-4 residues. For gangliosides the collapse pressures were lower and decreased from mono- to tri-sialogangliosides. Ganglioside monolayers on subphases at pH 1.2 showed increases in their collapse pressure. 4. The glycosphingolipid monolayers studied had various surface in their collapse pressure. 4. The glycosphingolipid monolayers studied had various surface potentials according to the complexity of the polar head group of the lipid. Attempts to calculate the dipolar contributions to the surface potential from each carbohydrate residue suggest that the second and third sialosyl residues in di- and tri-sialogangliosides contributed with a vertical dipole moment opposite to that of the first sialosyl residue.

The many faces (and phases) of ceramide and sphingomyelin II – binary mixtures

“…However, the crosssectional area contribution of these gangliosides does not reach values as small as those observed for the molecular area contribution of GM1, namely about 35 Å 2 (Carrer and Maggio 2001), which is about the minimum possible for two closely packed hydrocarbon chains perpendicular to the interface. This is consistent with previous reports indicating that the extended oligosaccharide chain of gangliosides and other GSLs, oriented perpendicularly to the interface (Maggio et al 1978b(Maggio et al , 1981Li et al 2002;Diociaiuti et al 2004), can largely Bfit^under the area of two closely packed hydrocarbon chains. For the more complex oligosaccharide polar head groups, slightly more spacing is required, especially at low surface pressures (Maggio et al 1981;Carrer and Maggio 2001).…”

Surface behavior of axolemma monolayers: Physico‐chemical characterization and use as supported planar membranes for cultured Schwann cells

“…The other conspicuous feature is a broad and diffuse bulge in the isotherm of total axolemma between about 13 mN/m and 30 mN/m. Figure 5b shows the surface potential normalized per unit of molecular surface density (usually denominated surface potential per molecule; see Gaines, 1966;Maggio et al, 1978;Maggio, 1992) as a function of the mean molecular area. The variation of this magnitude with the molecular packing reflects changes in the orientation or the location of dipolar components (Maggio et al, 1978;Maggio, 1992;Beitinger et al, 1989).…”

Induction of membrane fusion by polysialogangliosides

“…The glycosphingolipids were obtained and purified as in [ 1 ]. Glyceryl mono-oleate (99% pure) was from Sigma Chem.…”

“…Recently reported studies on the behaviour of gangliosides and neutral glycolipids at the air-water interface revealed that the complexity of the polar head group, and specially the presence of one or more sialic acids, greatly influences their surface properties [1].…”