The Surface Properties of Gangliosides: I. Monolayer Properties

Abstract

The monolayer properties of phospholipids have been well studied in recent years; however, the properties of glycosphingolipids, although of importance in cell recognition processes, have not been investigated as thoroughly. In this paper we report on the surface pressure-area, surface potential-area, and dipole moment-area isotherms of dipalmitoylphosphatidylcholine, DPPC, and the glycosphingolipids G M1 and G T1b. The gangliosides exhibit expanded liquid film behavior, with measurable surface pressures detectable at molecular areas of 1.5 nm 2 and 2.5 nm 2 for G M1 and G T1b, respectively. These large molecular areas are a consequence of the large headgroups of these lipids and their charged nature. In addition mixtures of the gangliosides and phospholipids have been studied. In the mixtures of DPPC and gangliosides a negative deviation of the surface pressure with area was observed, indicating a degree of association between the different lipids in the film. Although there have been some data published on these systems by other workers the data have been contradictory in nature.