Effect of Pressure on the Phase Transitions of Dimyristoylphosphatidylethanolamine and Dimyristoylphosphatidylcholine Bilayers

摘要

The temperature (T) - pressure (p) phase diagrams of the dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE) multilamellar vesicles were constructed by the method of high-pressure light transmittance. DMPC bilayer membrane undergoes pretransition at 13.9 deg C from the lamellar gel (L_ beta ') phase to the ripple gel (P_ beta ') phase, and succeedingly the main transition at 23.9 deg C from the P_ beta ' phase to the liquid crystalline (L alpha ) phase. The slopes of phase boundary, dT/dP, were 0.212 K MPa~(-1) for the main transition and 0.13 K MPa~(-1) for the pretransition, respectively. On the other hand, DMPE bilayer membrane undergoes transition at 56.8 deg C from the highly ordered subgel (L_c) phase to the L_ alpha phase. The value of dT/dp for this transition was 0.195 K MPa~(-1). The main transition of DMPE bilayer membrane was observed at 49.6 deg C and the value of dT/dp was 0.222 K MPa~(-1).