화학공학소재연구정보센터
Journal of the American Chemical Society, Vol.126, No.50, 16456-16465, 2004
A new tripodal receptor for molecular recognition of monosaccharides. A paradigm for assessing glycoside binding affinities and selectivities by H-1 NMR spectroscopy
A new tripodal receptor for the recognition of monosaccharides is described. The prototypical host 1 features a 1,35-substituted 2,4,6-tri ethyl benzene scaffold bearing three convergent H-bonding units. The binding ability of the t-octyl derivative la toward a set of octylglycosides of biologically relevant monosaccharides, including Glc, Gal, Man, and GlcNAc, was investigated by H-1 NMR in CDCl3. A protocol for the correct evaluation of binding affinities was established, which can be generally applied for the recognition of monosaccharides by H-1 NMR spectroscopy. A three-constant equilibrium model, including 1:1 and 2:1 host-guest association and dimerization of the receptor, was ascertained for the interaction of la with all the investigated glycosides. An affinity index, which we defined median binding concentration BC50 in analogy to the IC50 parameter, intended to address the general issue of comparing dimensionally heterogeneous binding data, and a limiting BC500 quantity describing intrinsic binding affinities were developed for evaluating the results. BC500 values for la range from 1 to 6 mM, indicating an intrinsic binding affinity in the millimolar range and a selectivity factor of 5 toward the investigated glycosides. The treatment has been extended to include any generic host-guest system involved in single or multiple binding equilibria.