EFFECT OF CHIRALITY ON THE FORMATION OF TUBULES FROM GLYCOLIPIDIC AMPHIPHILES

Pure enantiomers and racemic mixtures of glycolipids, derived from tri s(hydroxymethyl)aminomethane (Tris) rind aspartic acid, were synthesiz ed in order to study the impact of chirality on the formation of tubul es. The amphiphiles were obtained by classical peptide synthesis. Stru ctural analysis of pure enantiomeric and racemic mixtures of mono and digalactosylated Tris amphiphiles in aqueous medium was performed usin g transmission electron microscopy after negative staining with phosph otungstic acid or freeze-fracture. Tubular aggregates of similar to 45 0 nm in diameter and several microns in length were observed for the p ure enantiomeric mono- and digalactosylated amphiphiles. For the racem ic mixtures. the morphology of the aggregates depends on the bulkiness of the hydrophilic head. For the bulkier digalactosylated amphiphile, liposomes were formed. The monogalactosylated amphiphile arranges int o stacked bilayers. Thus, chirality favors the formation of tubules an d the aggregates obtained from the amphiphile's racemic mixture depend on the volume of the hydrophilic head.