Improving an all-atom force field

Experimentally well-characterized proteins that are small enough to be computationally tractable provide useful information for refining existing all-atom force fields. This is used by us for reparametrizing a recently developed all-atom force field. Relying on high statistics parallel tempering simulations of a designed 20 residue $\beta$-sheet peptide, we propose incremental changes that improve the force field’s range of applicability.

Figure 1

Comparison of the free-energy as a function of energy and backbone RMSD for beta3s in the (left) old version of the force field (obtained with default PROFASI version 1.0.1) and (right) that obtained after our corrections. The changes make a small shift in the weights in favor of the native minimum. Contour lines are separated by 1 $k_{B}T$. Both plots show free energy landscapes at $T\approx 283\mathrm{K}$ in energy and temperature scales callibrated with respect to their own set of parameters.