Effect of temperature on the phase behaviour of fully saturated DAPC lipid bilayer: A comparative molecular dynamics simulation study

Abstract

The plasma membrane is made of phospholipid bilayer in which membrane proteins are embedded. The physiochemical properties of the cell membrane are determinant in many important cellular processes. The lipid bilayer has a fluid like consistency and the fundamental structure and dynamic properties are dependent upon temperature. Depending upon temperature lipid bilayer has many phases namely gel phase (Lβ), liquid-crystalline phase (Lα), subgel phase (Lc), and ripple phase (Pβ). We have investigated the structural properties of DAPC lipid bilayer at two different temperatures, one above the phase transition temperature (at 350 K) and another below the phase transition temperature (300 K). We have been able to discriminate the two phases at two different temperatures and determine the phase behavior of DAPC lipid. We have found that change in temperature may have serious consequences for the structural properties of lipid bilayer systems. The reduced area per lipid and the corresponding ordering of the lipid acyl chain lead to phase change of the bilayer. Energy calculation also supports that the system at temperature 300 K is at gel phase. Preliminary studies of dynamic quantities like diffusion coefficient showed that this parameter is also sensitive to temperature and shows lower value at lower temperature indicating ordering at lower temperature.