Supramolecular helix and beta-sheet through self-assembly of two isomeric tetrapeptides in crystals and formation of filaments and ribbons in the solid state

Dutta, A., Dutt, A., Drew, M.G.B. and Pramanik, A. (2008) Supramolecular helix and beta-sheet through self-assembly of two isomeric tetrapeptides in crystals and formation of filaments and ribbons in the solid state. Supramolecular Chemistry, 20 (7). pp. 625-633. ISSN 1061-0278 doi: 10.1080/10610270701565194

Abstract/Summary

Single crystal X-ray diffraction studies show that the beta-turn structure of tetrapeptide I, Boc-Gly-Phe-Aib-Leu-OMe (Aib: alpha-amino isobutyric acid) self-assembles to a supramolecular helix through intermolecular hydrogen bonding along the crystallographic a axis. By contrast the beta-turn structure of an isomeric tetrapeptide II, Boc-Gly-Leu-Aib-Phe-OMe self-assembles to a supramolecular beta-sheet-like structure via a two-dimensional (a, b axis) intermolecular hydrogen bonding network and pi-pi interactions. FT-IR studies of the peptides revealed that both of them form intermolecularly hydrogen bonded supramolecular structures in the solid state. Field emission scanning electron micrographs (FE-SEM) of the dried fibrous materials of the peptides show different morphologies, non-twisted filaments in case of peptide I and non-twisted filaments and ribbon-like structures in case of peptide II.