Molecular dynamics simulation of a charged biological membrane

A molecular dynamics simulation of a membrane with net charge in its liquid-crystalline state was carried out. It was modeled by dipalmitoylphosphatidylserine lipids with net charge, sodium ions as counterions and water molecules. The behavior of this membrane differs from that was shown by other membranes without a net charge as a consequence of strong Coulomb interaction between atoms of adjacent phospholipids. The most remarkable effect produced by such interaction between neighboring lipids is a reduction of the surface area per phospholipid compared to an uncharged membrane. In addition, other properties of the membrane were also affected by this interaction between adjacent lipids such as the atom distribution across the membrane, the diffusion coefficient of the different components of the membrane and the order parameter of the phospholipid hydrocarbon region. Some comparisons of this membrane with dipalmitoylphosphatidylcholine membrane without net charge at similar conditions are presented. (C) 1996 American Institute of Physics.