Relationship between gramicidin conformation dependent induction of phospholipid transbilayer movement and hexagonal HII phase formation in erythrocyte membranes

Addition of gramicidin in sufficient concentration from dimethylsulfoxide or trifluoroethanol to isolated erythrocyte membranes induces hexagonal HII phase formation for the phospholipids. In contrast, addition from ethanol does not change the overall bilayer organization despite a similar extent of peptide incorporation. The same solvent dependence is observed for the enhancement of transbilayer reorientation of lysophospholipids and unspecific leak formation in intact erythrocytes at lower gramicidin concentrations. These results indicate that the (beta 6.3) conformation of the peptide is essential for all three membrane perturbing effects.