Evaluación del comportamiento no ideal de una bicapa lipídica de DPPC y DPPS con diferentes concentraciones de colesterol usando dinámica molecular.

Abstract

Charmm-GUI was used to build five molecular models of lipid bilayers containing 200 lipids of Dipalmitoylphosphatidylcholine (DPPC) and Dipalmitoylphosphatidylserine (DPPS) with cholesterol concentrations (CHL1) of 0, 15, 30, 50 and 70% to evaluate non – ideal behavior (condensation effect). A series of Molecular Dynamics simulations were performed using Gromacs, the energy minimization and the molecular systems equilibration were performed using NVT and NPT assemblies at a temperature of 315 K for a total of 10 ns. The variables were determined: molecular area, surface tension and Gibbs elasticity for each model. As the cholesterol concentration increases, the molecular area decreases, the surface tension fluctuates. The cholesterol level also affects the lipid bilayers hardness. The Gibbs elasticity was evaluated, resulting in hardness in the bilayer when it has 70% cholesterol in its composition. The system with the greatest flexibility was the lipid bilayer with 30% cholesterol. The surface pressure and Gibbs elasticity behavior of the simulations in relation to the experimental results are similar, demonstrating the non – ideal cholesterol behavior against phospholipids affecting the lipid bilayers properties and cell functionality as well. It is recommended to deepen the study of other factors that determine the non – ideal cholesterol behavior versus phospholipids in the lipid bilayers.