MOLECULAR-INTERACTIONS BETWEEN PHOSPHOLIPIDS AND GLYCOLIPIDS IN A LIPID BILAYER

Molecular interactions between phospholipids and glycolipids in a lipid bilayer have been investigated in terms of permeability, micropolarity, microviscosity, particle size, and zeta potential. Glycolipids used are 1,2-diacyl [beta-D-galactopyranosyl (1'-3)]-sn-glycerol (monogalactosyl diglyceride; MG) and 1,2-diacyl [alpha-D-galactopyranosyl (1'-6') beta-D-galactopyranosyl (1'-3)]-sn-glycerol (digalactosyl diglyceride; DG). Liposomal bilayer membranes are stabilized by the addition of suitable amounts of glycolipids, but higher amounts can destabilize the liposomes. Sugar chains in the glycolipids inhibit the permeability of glucose. Micropolarity is lowest for a 0.045 mole fraction of DG incorporated into the liposomes with cholesterol. The particle size is increased with an increase in the amount of glycolipids added. The absolute value of the zeta potential of the liposomes decreases on the addition of a glycolipid. An inhibiting effect of sugar chains on the aggregation of the liposomes is not found, because the sugar chains of MG and DG do not have sufficient chain lengths to inhibit the aggregation of the liposomes.