Molecular selective binding of aliphatic oligopeptides by bridged bis(β-cyclodextrin)s with aromatic diamine linkers

✍ Scribed by Yan Zhao; Juan Gu; Yong Cun Yang; Hong You Zhu; Rong Huang; Bi Jing

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 673 KB
• Volume: 930
• Category: Article
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2009.04.040

✦ Synopsis

Binding behavior of two aromatic diamine-bridged bis(b-cyclodextrin)s 1-2 with the aliphatic oligopeptides, i.e., Leu-Gly, Gly-Leu, Glu-Glu, Met-Met, Gly-Gly, Gly-Gly-Gly, and Gly-Pro was investigated at 25 °C in phosphate buffer (pH 7.20) by fluorescence, 1 H and 2D NMR spectroscopy. The results obtained from ROESY spectra show that the linker groups of bis(b-cyclodextrin)s 1-2 are partly self-included in the cyclodextrin cavity, and are entirely expelled out of the cyclodextrin cavity upon complexation with guest oligopeptides. Owing to the cooperative ''cyclodextrin-guest-cyclodextrin" sandwich binding mode, these bis(b-cyclodextrin)s not only afford high binding constants of up to 10 3 -10 4 M À1 for guest oligopeptides, but also can recognize the size and hydrophobicity of oligopeptides. As a result of multiple recognition mechanism, bis(b-cyclodextrin) 2 gives exciting residue selectivity up to 41.7 for Gly-Gly-Gly/Glu-Glu pair and high length selectivity up to 3.9 for the Gly-Gly-Gly/Gly-Gly pair. The molecular binding ability and selectivity are discussed from the viewpoints of induced-fit and multiple recognition between host and guest.