Planar asymmetric lipid bilayers of glycosphingolipid or lipopolysaccharide on one side and phospholipids on the other: membrane potential, porin function, and complement activation.

We have determined some physicochemical properties of the monosaccharide-type fraction (GSL-1) of glycosphingolipids, the major glycolipid components of the outer leaflet of the Gram-negative species Sphingomonas paucimobilis. These properties included the state of order of the hydrocarbon moiety, the effective molecular area, surface charge density, and intrinsic transmembrane potential profile of reconstituted planar asymmetric GSL-1/phospholipid bilayer membranes. We have, furthermore, investigated the insertion into and the function of porin channels in the reconstituted bilayers and the complement-activating capability of GSL-1 surfaces. All results were compared with respective data for deep rough mutant lipopolysaccharide of Salmonella minnesota R595. We found a remarkable agreement in most functional properties of the two glycolipids.