Effect of pressure on membranes

Besides temperature, hydrostatic pressure has been used as a physical-chemical parameter for studying the energetics and phase behavior of membrane systems. First we review some theoretical aspects of lipid self-assembly. Then, the temperature and pressure dependent structure and phase behavior of lipid bilayers, differing in chain configuration, headgroup structure and composition as revealed by using thermodynamic, spectroscopic and scattering experiments is discussed. We also report on the lateral organization of phase-separated lipid membranes and model raft mixtures as well as the influence of peptide and protein incorporation on membrane structure and dynamics upon pressurization. Also the effect of other additives, such as ions, cholesterol, and anaesthetics is discussed. Furthermore, we introduce pressure as a kinetic variable. Applying the pressure-jump relaxation technique in combination with time-resolved synchrotron X-ray diffraction, the kinetics of various lipid phase transformations was investigated. Finally, also new data on pressure effects on membrane mimetics, such as surfactants and microemulsions, are presented.