Selective Recognition of Trp- and Tyr-Rich Oligopeptides by Self-Assembled Coordination Hosts

Abstract

Abstract A coordination host recognized various aromatic peptides containing Trp and Tyr residues in a highly sequence-selective fashion. For example, two similar hexa-peptides, Ac-Ser-Gly-Ala-Trp-Trp-Ala-NH2 and Ac-Ala-Trp-Trp-Ala-Gly-Ser-NH2, were selectively discriminated by the restricted inner space of coordination cages. We also demonstrated that the charged peptides were efficiently discriminated by the cage owing to the highly cationic property of the cage (12+). Furthermore, the cages selectively discriminated two similar peptides, Ac-Ala-Trp-Trp-NH2 and Ac-Ala-Tyr-Tyr-NH2, because of differences in the strength of charge-transfer interaction between the cage and the electron-rich aromatic residues. This selectivity was controlled by modulating the solution pH. The colorization of the aromatic peptide solutions by charge-transfer interaction could also be applicable to the naked-eye recognition of three aromatic residues, Trp, Tyr, and Phe.