Effect of dehydroepiandrosterone on phosphatidylserine or phosphatidylcholine bilayers: DSC and X-ray diffraction study

The effect of dehydroepiandrosterone (DHEA) on the thermotropic and structu ral properties of phosphatidylserine or phosphatidylcholine membranes was i nvestigated by differential scanning calorimetry and X-ray diffraction. At molar fractions of sterol, X (sterol), less than similar to 0.2, DHEA inter acts with both types of model membranes, depressing the melting temperature and reducing the enthalpy of melting. At higher concentrations, phase sepa ration of DHEA occurs with appearance of crystallites of the S2 monohydrate form. (C) 2000 Elsevier Science B.V. All rights reserved.