Tubular structures formed by pig erythrocyte globoside in aqueous systems

The relationship between the structure of the headgroup of sphingolipids and their ability to form complex high axial ratio microstructures

Ceramides with chemically modified polar headgroups were prepared and examined for their ability to form complex high axial ratio microstructures (CHARMS), potential drug delivery vehicles. In general, if the modified ceramide had either a hydrogen bond donor or acceptor at C-1 and C-3, including hydrophobic or hydrophilic groups attached to C-1 microstructures formed. Tolerated groups include amides, esters, sulfonates, and ethers. If modification at C-3 added significant bulk (greater than four carbons regardless of hydrophilicity), then amorphous aggregates formed. Ceramides with C-1 and C-3 bridged through a cyclic structure also made microstructures. By using a sphingolipid with an amine headgroup, CHARMs may be modified covalently after formation.

Thermodynamic-geometric correlations for the morphology of self-assembled structures of glycosphingolipids and their mixtures with dipalmitoylphosphatidylcholine

The morphology of aqueous dispersions of five neutral glycosphingolipids (GalCer, GlcCer, LacCer, asialo-GM2, asialo-GM1), sulfatide, and five gangliosides (GM3, GM2, GM1, GD1a and GT1b) and their mixtures with dipalmitoylphosphatidylcholine was studied by negative staining electron microscopy. The morphological features are interpreted on the basis of thermodynamic and geometric constraints previously studied in these systems (Maggio, B (1985) Biochim. Biophys. Acta 815, 245-258). The correlation between the theoretical predictions and the experimental findings are in reasonable agreement. Small changes in the molecular parameters of the individual glycosphingolipids or in their proportion in mixtures with dipalmitoylphosphatidylcholine bring about remarkable variations on the type of structure formed, its radius of curvature and thermodynamic stability.

Ganglioside headgroup dynamics

Gangliosides, spin-labelled specifically on N-acetylneuraminic acid residues or on random-headgroup sugars, have been used to extend previous studies of headgroup behaviour. Headgroup sugar mobility is seen to be homogeneous and relatively unrestricted in a range of systems including three lines of cultured cells. The effects of temperature and pH have been considered. Binding of small quantities of the lectin, wheat germ agglutinin, was found to increase average headgroup mobility for gangliosides in lipid bilayers, most likely as a result of a disordering effect on ganglioside clusters.