Predicting order and disorder for β-peptide foldamers in water.

Following a quantitative validation approach, we tested the AMBER ff03 and GAFF force fields with the TIP3P explicit water model in molecular dynamic simulations of β-peptide foldamers. The test sequences were selected to represent a wide range of folding behavior in water: compact helix, strand mimetic geometry, and the state of disorder. The combination AMBER ff03-TIP3P successfully predicted the experimentally observed conformational properties and reproduced the NOE distances and backbone (3)J coupling data at a good level. GAFF was unable to produce folded structures correctly due to its biased torsion potentials. We can recommend AMBER ff03-TIP3P for simulations involving β-peptide sequences in aqueous media including ordered and disordered structures.