The water molecules orientation around the dipalmitoylphosphatidylcholine head group: A molecular dynamics study

We have performed 3 ns MD simulation of phospholipid bilayer–water system in liquid crystalline state, consisting of 128 saturated dipalmitoylphosphatidylcholine (DPPC) and 3655 water molecules, thus constituting ≈40%≈40% by weight, which corresponds to a fully hydrated lipid bilayer. It is shown that at average the hydrogen atoms of water are oriented towards the phosphorus atoms and the negatively charged oxygen atoms towards the nitrogen atoms. The electric potential and the charge density of water molecules along the bilayer normal are determined. It is stated that in DPPC bilayers both lipid protrusions and water ordering take place.