The influence of ion species on phosphatidylcholine bilayer structure and packing.

The effects of various monovalent cations and anions on the bilayer packing and structure of dipalmitoylphosphatidylcholine were studied using X-ray diffraction and differential scanning calorimetry. It was observed from the X-ray diffraction studies that monovalent salts, in general, have no effect on bilayer packing. The results of DSC studies on metal chloride systems are consistent with the interpretation that cations in general and Li+ in particular bind to DPPC bilayers. The effect of potassium salts on pre- and main-transition temperatures suggest that anions, such as Acetate-, also significantly bind to DPPC head groups.