Interaction of dehydroepiandrosterone with phospholipid membranes:: An infrared spectroscopy investigation

The interaction between dehydroepiandrosterone (DHEA) and its sulfate metabolite (DHEA-S) with deuterated dimirystoylphosphatidylcholine (DMPC-d(54)) was investigated by FTIR spectroscopy. DHEA, as cholesterol, induces some conformational order in the liquid-crystalline phase of DMPC-d(54). Attenuated total reflectance (ATR) measurements performed on oriented DMPC-d(54)/steroids samples have shown that in the gel phase, the acyl chains of DMPC-d(54) become more normal to the bilayer surface in the presence of DHEA or cholesterol. On the other hand, DHEA-S increases the number of gauche conformers along the hydrocarbon chains of DMPC-d(54). No evidence for the presence of hydrogen bond was found between both steroids and the C-13 labeled carbonyl group of hydrated DMPC. (C) 1998 Elsevier Science B.V.