The Influence of Monovalent Anions on Dipalmitoylphosphatidylcholine Bilayer Phase Transitions: A Time Resolved X-Ray Diffraction Study

Abstract

The effect of monovalent anions on the packing structures and transitions of the lamellar phases of dipalmitoylphosphatidylcholine bilayers has been investigated at the Daresbury Synchrotron Laboratory (U.K.). Fully hydrated DPPC bilayers in the presence of 1M KBr swell past the usual repeat spacing observed in water by approximately 20Å and in the presence of 1M KSCN form an interdigitated gel phase. The transition temperatures, determined by changes in the bilayer parameters in the small and wide angle scattering profiles, occur at temperatures previously observed. Our observations also indicate that the changes in the bilayer unit cell produced by the presence of Br or CNS- do not change the nature of the phase transition.