Improved prediction of bilayer and monolayer properties using a refined BMW-MARTINI force field

MIGUEL V; PERILLO MA; VILLARREAL MA

BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016

0005-2736

Coarse-grained (CG) modelsallow enlarging the size and time scales that are reachable by atomisticmolecular dynamics simulations. A CG force field (FF) for lipids and aminoacids that possesses a polarizable water model has been developed following theMARTINI parametrization strategy, the BMW-MARTINI. We tested the BMW-MARTINI FF capability to describe some structuraland thermodynamical properties of lipid monolayers and bilayers. We found that,since the surface tension values of oil/water interfaces calculated with themodel are not correct, compression isotherms of lipid monolayers presentartifacts. Also, this FF predicts DPPC and DAPC bilayers to remain in the Lαphase at temperatures as low as 283K, contrary to the expected from theirexperimental Tm values. Finally, simulations at constant temperature of bilayersof saturated lipids belonging to a PC homologous, showed an increase in the meanmolecular area (Mma) upon increasing the chain length, inversely to the experimentalobservation.We refined BMW-MARTINI FFby modifying as few parameters as possible in order to bring simulated andexperimental measurements closer. We have also modified structural parametersof the lipid geometry that do not have direct influence in global properties ofthe bilayer membranes or monolayers, but serve to approach the obtained CGgeometry to atomistic reference values. The refined FF is able to betterreproduce phase transition temperatures and Mma for saturated PC bilayers thanBMW-MARTINI and MARTINI FF. Finally, the simulated surface pressure-Mma isothermsof PC monolayers resemble the experimental ones and eliminate serious artifactsof previous models.