Formation and characterization of planar lipid bilayer membranes from synthetic phytanyl-chained glycolipids

The formability, current-voltage characteristics and stability of the plana r lipid bilayer membranes from the synthetic phytanyl-chained glycolipids, 1,3-di-O-phytanyl-2-O-(beta-glycosyl)glycerols (Glc(Phyt)(2), Mal(N)(Phyt)( 2)) were studied. The single bilayer membranes were successfully formed fro m the glycolipid bearing a maltotriosyl group (Mal(3)(Phyt)(2)) by the fold ing method among the synthetic glycolipids examined. The membrane conductan ce of Mal(3)(Phyt)(2) bilayers in 100 mM KCl solution was significantly low er than that of natural phospholipid, soybean phospholipids (SBPL) bilayers , and comparable to that of 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DP hPC) bilayers. From the permeation measurements of lipophilic ions through Mal(3)(Phyt)(2) and DPhPC bilayers, it could be presumed that the carbonyl groups in glycerol backbone of the lipid molecule are not necessarily requi red for the total dipole potential barrier against cations in Mal(3)(Phyt)( 2) bilayer. The stability of Mal(3)(Phyt)(2) bilayers against long-term sta nding and external electric field change was rather high, compared with SBP L bilayers, Furthermore, a preliminary experiment over the functional incor poration of membrane proteins was demonstrated employing the channel protei ns derived from octopus retina microvilli vesicles. The channel proteins we re functionally incorporated into Mal(3)(Phyt)(2) bilayers in the presence of a negatively charged glycolipid. From these observations, synthetic phyt anyl-chained glycolipid bilayers are promising materials for reconstitution and transport studies of membrane proteins. (C) 1999 Elsevier Science B.V. All rights reserved.