Conformational analysis of β-turn structure in tetrapeptides containing proline or proline analogs

Article abstract of DOI:10.1016/S0040-4039(97)00529-7

In order to evaluate the influence of cyclic secondary amino acids on the stability of β-turn structure, we have prepared Ac-Gly-L-Xxx-L-Leu-Gly-N(CH₃)₂ (Xxx = Aze, 4-membered ring: 1, Xxx = Pro, 5-membered ring: 2, Xxx = Pip, 6-membered ring: 3). The NOE cross peaks that support β-turn structure were observed in 1-3. The NOE cross peak between both terminals of the synthetic peptides, however, was observed only in the NOESY spectra of 2. This result indicates that 5-membered ring side chain in proline plays a very important role in the formation of β-hairpin structure.