Effects of Ions on the Dynamics and Structural Behavior of Saturated and Unsaturated Phospholipids in Bilayers

The affinity of KCl and CaCl2 salt solutions for the dioleoylphosphatidylcholine (DOPC) and dipalmitoylphosphatidylcholine (DPPC) lipid membrane was investigated by means of molecular dynamics simulations with an all-atom force field. The simulations revealed that Calcium ion is attracted to the headgroup region with its concentration being maximal in the vicinity of the phosphate groups of unsaturated lipid (DOPC) and in saturated lipid (DPPC). Potassium do not preferentially adsorb to the membrane. While chloride does not show a strong affinity for the headgroup but merely compensate for positive charge of countercations. At the end, Thermodynamics and dynamics properties of the bilayers that include KCl and CaCl2 solutions and free of ions such as the density, the energy, mean square displacement diffusion coefficient, root mean square deviation and the order parameter is calculated.

Keywords:

Ions , Molecular dynamics , saturated and unsaturated phospholipids , bilayer lipids