Are NMR-derived model structures for β-peptides representative for the ensemble of structures adopted in solution?

The data fit, but the structures are different. Two methods for the interpretation of NMR data of a β-hexapeptide are compared. While the simulated annealing procedure suggests the formation of a (P)-2 8-helix, unrestrained molecular dynamics simulations indicate that the NMR data can also be described by a much broader ensemble of conformations, in which (P)-2.512-helical structures are prominent (see diagram). (Graph presented).