Sugar-derived oxazolone pseudotetrapeptide as γ-turn inducer and anion-selective transporter

Abstract

The intramolecular cyclization of a C-3-tetrasubstituted furanoid sugar amino acid-derived linear tetrapeptide afforded an oxazolone pseudo-peptide with the formation of an oxazole ring at the C-terminus. A conformational study of the oxazolone pseudo-peptide showed intramolecular C=O···HN(II) hydrogen bonding in a seven-membered ring leading to a γ-turn conformation. This fact was supported by a solution-state NMR and molecular modeling studies. The oxazolone pseudotetrapeptide was found to be a better Cl−-selective transporter for which an anion–anion antiport mechanism was established.

Progress and prospects toward supramolecular bioactive ion transporters

“…This was also supported by DFT calculation studies which showed the g-turn conformation stabilized by an intramolecular (II)NHÁ Á ÁOQC hydrogen bonding in a sevenmembered ring. 116 Among 11a and 11b, only 11a showed significant ion transport activity, which indicates that the amino group is necessary for the desired ion transport. Furthermore, the precursor of 11a, the compound that does not contain the oxazolone ring and lacks the g-turn did not show any ion transport activity, indicating the importance of the ring for inducing the g-turn in 11a which eventually leads to anionselective ion transport across the lipid bilayer membrane.…”