Pressure effects on the structure and phase behavior of phospholipid-gramicidin bilayer membranes

Abstract

We investigated the effect of incorporation of gramicidin D (GD) on the structure and phase behavior of aqueous dispersions of DPPC phospholipid bilayers. SAXS, DSC, 2 H-NMR and FTIR spectroscopy were used to detect topological and conformational changes upon incorporation of GD into the lipid bilayer. The data show that, depending on the GD concentration, the structure of the temperature- and pressure-dependent lipid phases is significantly altered by the insertion of the polypeptide, but also the lipid matrix has the ability to modulate the conformation of the inserted polypeptide. No pressure-induced unfolding of the polypeptide is observed up to pressures of 10 kbar.