Comparative study on using force fields of three varying coarse-graining levels in the computational study of the behavior of DPPC lipid bilayer in the presence of DMSO.*

One of the main factors of a successful simulation is employment of a good set of force fields (ff) and the current understanding of the nature of coarse-graining in multiscale simulations is still limited.
Our goal is to systematically investigate if and how differently (or similarly) simulations adopting different coarse-graining levels lead to a certain behavior of a lipid bilayer in the presence of DMSO, such as the area per lipid molecule, the membrane thickness, and ordering. Previous studies on this system were done in slightly different study system sizes, compositions, temperatures, etc. Therefore, to eliminate any factor other than the coarse-graining level, we performed MD simulations on the identical study system using same set of parameters other than the adaptation of three different molecular modeling methods: (1) fully united-atom simulation using gromacs ff for all molecules, (2) fully coarse-grained simulation using Martini ff for all molecules, and (3) hybrid MD simulation using OPLSaa ff for DMSO and Martini ff for water and lipids molecules. The summary of our findings will be presented.