Abstract
Phospholipid bilayer membranes undergo various phase transitions depending on environmental factors such as temperature, pressure, salt concentration and so on. Although the differential scanning calorimetry (DSC) is especially effective in detecting the bilayer phase transitions, combination of the thermal information with results obtained from pressure measurements enables us to deepen a thermodynamic understanding of the bilayer transitions. Phase transitions of bilayer membranes formed by phospholipids, which are frequently used in studies of biological membranes, were explained and phase transition measurements under high pressure were introduced. Next the bilayer phase transitions for phosphatidylethanolamine homologues with different kinds of hydrophobic chains (degree of unsaturation in acyl chains) and different-sized polar head groups were taken up and the bilayer phase transitions were thermodynamically characterized in terms of pressure dependence of phase-transition temperatures, temperature-pressure phase diagrams and thermodynamic quantity changes associated with phase transitions.
