Chain ordering of hybrid lipids can stabilize domains in saturated/hybrid/cholesterol lipid membranes

¹ Department of Materials and Interfaces, Weizmann Institute of Science - Rehovot, Israel, 76100
² Department of Applied Physics, CalTech - Pasadena, CA, USA

^a tetsujava@hotmail.com

Received: 26 May 2010
Accepted: 8 July 2010

Abstract

We use a liquid-crystal model to predict that hybrid lipids (lipids that have one saturated and one unsaturated tail) can stabilize line interfaces between domains in mixed membranes of saturated lipids, hybrid lipids, and cholesterol (SHC membranes). The model predicts the phase separation of SHC membranes with both parabolic and loop binodals depending on the cholesterol concentration, modeled via an effective pressure. In some cases, the hybrid lipids can reduce the line tension to zero in SHC membranes at temperatures that approach the critical temperature as the pressure is increased. The differences in the hybrid saturated tail conformational order in bulk and at the interface are responsible for the reduction of the line tension.