Merging two coarse-grained force fields: Extension of the ELBA force field for dipeptides and lipopeptides through SIRAH force field.

The usefulness and importance of molecular simulations to investigate dynamic processes and interactions mechanisms at the molecular level were recognized in the 2013 Nobel Prize in Chemistry for the "development of multiscale models for complex chemical systems ". Force fields in coarse-grained resolution stand out in molecular dynamics simulations by enabling the achievement of a larger space-time scale. Thus, the focus of this work was the development of a coarse-grained force field that allowed the simulation of self-assembled systems based on dipeptides and lipopeptides. In this sense, the ELBA coarse-grained force field developed for simulations of aqueous biomembranes, and SIRAH coarse-grained force developed for simulations of proteins were merged together into a new and consistent coarse-grained force field. In ELBA, electrostatics is described by monopoles and dipoles with a shifted and truncated potential. In SIRAH, electrostatics is treated only with monopoles, including long-range corrections based on Ewald techniques. Thus, cross interactions between SIRAH amino acids's beads with ELBA water (a Lennard-Jones sphere with a point dipole) were reparametrized based on the electrostatic charging process through thermodynamic integration until the electrostatic free energy of solvation matches the underlying atomistic reference values. The dispersion-repulsion contribution to the free energy of solvation was also reparametrized adjusting the Lennard-Jones potential parameters. The optimized parameters obtained with the calibration were applied in the simulation of dipeptides and lipopeptides and the results of these simulations were validated with experimental data and atomistic simulations.