EFFECT OF HIGH-PRESSURE ON THE STRUCTURE OF DIPALMITOYLPHOSPHATIDYLCHOLINE BILAYER-MEMBRANES - A SYNCHROTRON X-RAY-DIFFRACTION AND FTIR SPECTROSCOPY STUDY USING THE DIAMOND-ANVIL TECHNIQUE

The effect of high pressure, up to 20 kbar, on multilamellar vesicles of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) was examine d by using FT-IR spectroscopy and Synchrotron-X-ray diffraction in the small- and wide-angle scattering region. The temperature and pressure range studied permitted us to explore the phase behaviour of DPPC fro m the liquid-crystalline phase through various gel phases up to the pr essure region where bulk water freezes and freeze-induced dehydration of the membrane occurs. To our knowledge this is the first study where the structure and phase behaviour of an amphiphilic lipid system has been studied up to these high pressures. The use of pressure to study the lipid gel state has revealed several new phases which may not exis t at very low temperatures at ambient pressure. (C) 1998 Elsevier Scie nce Ireland Ltd. All rights reserved.