Dilatometry of dipalmitoyllecithin-cholesterol bilayers

Abstract

The interactions of cholesterol and dipalmitoylphosphatidylcholine in bilayers were investigated by differential scanning dilatometry and related techniques. Dipalmitoylphosphatidylcholine bilayers ranging from 0 to 50 mol % cholesterol were studied over a temperature range of 0-50.degree. C. These investigations allowed construction of a 3 dimensional surface with dimensions of mole fraction of cholesterol, temperature and apparent partial specific volume. Much of the phenomenology reported for dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylcholine-cholesterol bilayers appears and can be interrelated on this surface. In addition to the thermotropic events associated with the system, 2 cholesterol-induced events at 17.5-20 and 29 mol % cholesterol are particularly in evidence.