Molecular Dynamics Study of Oxidized Lipid Bilayers in NaCl Solution

Abstract

Polyunsaturated lipids are major targets of free radicals forming oxidized lipids through the lipid peroxidation process. Thus, oxidized lipids play a significant role in cell membrane damage. Using atomistic molecular dynamics (MD) simulations to investigate the dynamics of oxidized lipid bilayers, we examined the effects of NaCl on them. Lipid bilayer systems of 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphatidylcholine (PLPC) and 4 oxidation products, namely, 9-tc-hydroperoxide linoleic acid, 13-tc-hydroperoxide linoleic acid, 9-oxononanoic acid, and 12-oxo-9-didecadienoic acid in 0, 0.06, and 1 M NaCl solution were studied. These 51 systems, combined over 15 μs of total simulation time, show Cl(-) anions remaining in the water phase and Na(+) cations permeating into the headgroup region of the bilayer leading to membrane packing. The effects of NaCl on thickness and area per molecule were found to be independent of the concentration of oxidized lipids. NaCl disturbed the bilayers with aldehyde lipids more than those with peroxide lipids. The key finding is that oxidized lipids bend their polar tails toward the water interface. This behavior was monitored by following the time evolution of hydrogen bonds between the oxidized functional groups of different lipids, and the concomitant increase of hydrogen bonds between oxidized functional groups and water molecules. Our results also show that the number of hydrogen bonds should be considered as an equilibration parameter: Very long simulations are needed to equilibrate systems with high NaCl concentrations.

Magnesium sulfate against oxidative damage of membrane lipids: A theoretical model

“…In this case, lipid chains are hindered to move close to the surface; then, the • OH faces more difficulty in reaching the unsaturated sites of the lipid chain. The results for increasing the membrane thickness and decreasing the area per lipid have also been reported by Jarerattanachat et al and Jurkiewicz et al using different salts.…”

Effect of Sodium and Chloride Binding on a Lecithin Bilayer. A Molecular Dynamics Study

“…Numerous MD studies on ion-membrane interactions were performed in the past, e.g., focusing on the kinetics, stoichiometry and structural aspects of ion-lipid binding [19,20,21,22,23] and the specific ion effects thereof [24,25,26,27]. Partly, the results have been found to depend strongly on the employed force field [22], and it was emphasized that careful force-field optimization might be required to achieve simulation results in agreement with experimental findings [14].…”

“…When lipid bilayers are immersed in aqueous electrolyte solutions in comparison to pure water, MD simulations evidence a reduction of membrane fluidity (i.e., of lateral lipid diffusion), a reduction of the area per lipid and an increase in membrane bilayer thickness [14,19,23,29]. Similar findings were obtained experimentally [4], although the influence of salt concentration on some structural membrane properties appears to be more complex in the case of certain salts.…”

Non-thermal effects of microwave in sodium chloride aqueous solution: Insights from molecular dynamics simulations

“…A series of investigations have also been done to evaluate the biological effects and physicochemical characteristic of NaCl [44][45][46][47][48][49][50][51][52][53][54][55][56][57] by MD simulations. It is successful reproduction and development in the experimental research of NaCl aqueous solution, such as the structural properties [58,59], dielectric properties [60,61], hydrogen bond dynamics structural relaxation properties [62], electric conductivity [63,64].…”