Peptide Foldamers: from Spectroscopic Studies to Applications.

Peptide foldamers are synthetic oligopeptides which attain a few, specific, constrained conformations in solution. Here, we review our contributions to the study of the structural features of several foldamers, comprising C\u3b1-tetrasubstituted aminoacids, by spectroscopic techniques and, in particular, by a combined approach employing time-resolved energy transfer (FRET) experiments and molecular modeling to determine interprobe distances and orientations. Our data show that, for rigid systems, the commonly used assumption of random orientation of donor and acceptor is unjustified, and that in these cases a correct evaluation of the orientation factor is mandatory for meaningful structural determinations. Finally, we illustrate some applications of peptide foldamers in studies on the kinetics of protein folding and on the realization of peptide-based molecular devices.