Carbohydrate affinity interactions

Polymer adsorption has also been adapted to QCM sensing whereby biofunctional thin films are adsorbed on the crystal surface with non-specific binding controlled by tuning of polymer composition. This approach proved successful as applied to carbohydrate-protein interaction by Matsuura et al. through adsorption of lactose bearing amphiphilic polymers on hydrophobic surfaces which then showed RCA12o and peanut lectin (PNA) affinity [33]. Carbohydrate surfaces prepared by photo insertion into an adsorbed polymer were tested by QCM and showed the predicted affinities [34] while in another example a covalently bound glycopolymer demonstrated Concanavalin A detection ability [35]. 

Many of these techniques have also been successfully utilized for the identification of inhibitors of protein-carbohydrate interactions. ELIS As are often employed, and their utility is illustrated in the efforts to identify selectin inhibitors [51-53]. However, other assays such as fluorescence polarization [33, 54] and carbohydrate affinity matrices [55] have also been utilized. These methods have provided valuable information about the substrate specificity of a number of carbohydrate-binding proteins and led to the discovery of many useful inhibitors. Still, there remains an acute need to develop effective high-throughput assays. 

M. I. Chavez, P. Vidal, N. Aboitiz, F. Freire, C. Andreu, G. Asensio, M. Muraki, J. L. Asensio, F. J. Canada, and J. Jimenez-Barbero, On the importance of carbohydrate-aromatic interactions for the molecular recognition of oligosaccharides by proteins. NMR studies of the structure and binding affinity of AcAMP2-like peptides with non natural napthyl and fluoro-aromatic residues, Chem. Eur. J., (2005) 7060-7074. 

Biotin-derivatized carbohydrates can be immobilized on a streptavidin-coated substrate through the affinity interaction of the streptavidin-biotin pair to create carbohydrate microarrays. Biotin-derivatized carbohydrates include carbohydrate hgands that are biotinylated via a short aliphatic spacer or at the peptide part of glycopeptides. Several commercially available streptavidin-coated microweU plates can be apphed when biotin-derivatized carbohydrates are available, such as the streptavidin-coated 384-well plate with a well volume 25 pi (4,18) and a streptavidin-coated 192-spot shde format (27). The first was designed to be in maximal proximity to the traditional immunochemical assay using commercial streptavidin-coated black 384-well plates. 

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