Small peptides 1 and 2, which differ only in that 1 possesses a BOC-Phe res
idue at the N-terminus, where 2 bears a BOC-(tau-benzyl)His, were found to
exhibit very different structures. In both the solid state (X-ray) and in s
olution (NMR and in), peptide 1 exists as a beta-turn, whereas peptide 2 ex
ists in a conformation that resembles the Asx-Pro motif.