Systematic implicit solvent coarse graining of DMPC lipids
(English)Article in journal (Refereed) Submitted
A 10-site coarse-grained implicit solvent model of DMPC phospholipid is developed with effective solvent-mediated potentials derived using the inverse Monte Carlo method. The potentials providing for the coarse-grained model the same site-site RDFs, bond and angle distributions as those computed in atomistic simulations were computed for four different lipid-water molar ratios.It was shown that there is a significant concentration dependence for both effective potentials and properties of lipid bilayers simulated using these potentials. Thus, effective potentials computed at low lipid concentration favour to more condensed and ordered structure of the bilayer with lower average area per lipid, while potentials obtained at higher lipid concentrations provide more fluid-like structure. Introduction of bending angle interaction into coarse-grained model makes effective potentials somewhat less concentration-dependent. The best agreement with the reference data and experiment was achieved using the set of potentials derived from atomistic simulations at 1:30 lipid:water molar ratio providing full hydration of DMPC lipids in bilayer. Despite theoretical limitations of the structure-based approach expressed in state point dependence of the effective potentials, all the resulting potentials provide a stable bilayer structure with correct partitioning of different lipid groups across the bilayer as well as acceptable values of the average lipid area and compressibility. Another important property demonstrated by the model is liquid/gel phase transition observed at lowering the temperature. In addition to bilayer simulations, the model has proven its robustness in modeling of self-aggregation of lipids from randomly dispersed solution to ordered bilayer structures, bicells and vesicles.
Research subject Physical Chemistry
IdentifiersURN: urn:nbn:se:su:diva-94762OAI: oai:DiVA.org:su-94762DiVA: diva2:655502