Binding behavior of aliphatic oligopeptides by bridged and metallobridged bis(beta-cyclodextrin)s bearing an oxamido bis(2-benzoic) carboxyl linker.
beta-Cyclodextrin dimers bearing an oxamido bis(2-benzoic) carboxyl linker (1) or its metal complexes (2 and 3) were newly synthesized, and their inclusion complexation behavior with a series of representative aliphatic oligopeptides, i.e., Leu-Gly, Gly-Leu, Gly-Pro, Glu-Glu, Gly-Gly, Gly-Gly-Gly, and Glu(Cys-Gly), was elucidated by means of UV/vis, circular dichroism, fluorescence, and 2D NMR spectroscopy in Tris-HCl buffer solution (pH 7.4) at 25 degrees C. The results obtained indicated that metallobridged bis(beta-cyclodextrin)s 2 or 3 could significantly enhance the original molecular binding abilities of parent bis(beta-cyclodextrin) 1 toward model substrates through the cooperative binding of two cyclodextrin moieties and the additional chelation effect supplied by the coordinated metal centers. It is interesting that hosts 2 and 3 displayed an entirely different fluorescence behavior upon complexation with guest oligopeptides. Among the guest peptides examined, 3 showed the highest complex formation constant of 68 200 M(-)(1) for Glu-Glu, up to 510-fold as compared with 1 (135 M(-)(1)), while 1 gave excellent molecular selectivity for Glu(Cys-Gly)/Glu-Glu pair, up to 51-fold. The molecular binding ability and selectivity were discussed from the viewpoints of the induced-fit and multiple recognition mechanism between host and guest.
Liu
Yu
Y
Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, P. R. China. yuliu@public.tpt.tj.cn
Zhao
Yan-Li
YL
Chen
Yong
Y
Ding
Fei
F
Chen
Guo-Song
GS
D000577:Amides / Q000737:chemistry / Q000378:metabolism; D001952:Bridged-Ring Compounds / Q000737:chemistry / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000737:chemistry / Q000378:metabolism*; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D047392:beta-Cyclodextrins / Q000737:chemistry / Q000378:metabolism*
D000577:Amides; D001952:Bridged-Ring Compounds; D003432:Cross-Linking Reagents; D009842:Oligopeptides; D047392:beta-Cyclodextrins