Validation of the GROMOS 54A7 Force Field with Respect to β-Peptide Folding

The recently developed GROMOS 54A7 force field, a modification of the 53A6 force field, is validated by simulating the folding equilibrium of two beta-peptides which show different dominant folds, i.e., a 3(14)-helix and a hairpin, using three different force fields, i.e., GROMOS 45A3, 53A6, and 54A7. The 54A7 force field stabilizes both folds, and the agreement of the simulated NOE atom-atom distances with the experimental NMR data is slightly improved when using the 54A7 force field, while the agreement of the (3)J couplings with experimental results remains essentially unchanged when varying the force field. The 54A7 force field developed to improve the stability of a-helical structures in proteins can thus be safely used in simulations of beta-peptides.