β-peptides with different secondary-structure preferences: How different are their conformational spaces?

The conformational spaces accessible to two β-hexapeptides in MeOH at 298 K and 340 K are investigated by molecular-dynamics simulation with an atomistic model of both solute and solvent. The structural properties of these peptides have been previously studied by NMR in MeOH at room temperature. The experimental data could be fitted to a model (P)-12/10-helix for one of the peptides and a model hairpin with a ten-membered H-bonded turn for the other. The goal of the present work is to determine whether the conformational spaces accessible to these two peptides of seemingly different conformational properties contain any common regions. In other words, to what extent are the evident differences found at the macroscopic level also present at the microscopic structural level? It is found that, for the two peptides studied, the conformational spaces sampled in the respective simulations show significant overlap.