THE EFFECT OF ETHANOL ON THE STRUCTURE OF PHOSPHATIDYLSERINE BILAYERS

Thermotropic and structural effects of ethanol on phosphatidylserine ( PS) membranes were investigated by differential scanning calorimetry ( DSC) and X-ray diffraction. It was found that up to 15% (v/v) added et hanol, there is little change in the melting temperature of the phosph olipid and no change in the interbilayer (d) spacing in the gel phase, indicating that there is no interdigitation of the hydrocarbon chains . Above the melting temperature of the phospholipid, a large decrease of the d spacing, due primarily to a decrease in the thickness of the bilayer, was found. Ethanol molecules located in the headgroup region apparently expand the area available to the headgroups with concomitan t coiling of the acyl chains, resulting in marked thinning of the lipi d layer. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.