Abstract
Temperature- and pressure-induced bilayer phase transitions of a series of diacylphosphatidylcholines containing two equivalent linear saturated acyl chains (CnPC: n = 12 – 22) were comprehensively revealed by constructing the temperature (T) – pressure (p) phase diagrams and determining thermodynamic quantities of the phase transitions, which were obtained by combined methods of differential scanning calorimetry under atmospheric pressure and light-transmittance measurements under high pressure. The T–p phase diagrams clarified various interesting aspects of the phase behavior, e.g., polymorphism between the gel phases, change in the gel-phase stability and pressure-induced bilayer interdigitation. Especially, the interdigitation was found to be induced in bilayers of CnPCs for 14 to 21. It turned out from the thermodynamic quantities that the sub-, pre- and main transition are, respectively, an acyl chain-length dependent transition with slow kinetics, an acyl chain-length independent transition with fast kinetics and an acyl chain-length dependent transition with fast kinetics, respectively. The interaction between CnPC molecules in the bilayer membrane was also deduced from the systematic consideration on the bilayer phase transitions of CnPCs.
https://ror.org/044vy1d05 
