The binding of monosaccharides to wheat germ agglutinin: fluorescence and NMR investigations

The synthesis of N-acetyl- and N-trifluoroacetyl-glucosaminides was reported. The interaction of these compounds with wheat germ agglutinin, a plant lectin specific for N-acetyl-glucosamine and sialic acid, was investigated by two complementary approaches: 1H and 19F NMR, and fluorescence spectroscopy. This last technique relies on the existence of a competitive equilibrium involving the protein, the ligand and O-(methylumbelliferyl)-N-acetyl-glucosaminide, a fluorescent saccharide. The binding constants and the chemical shifts in the complex were determined and were related to the protein structure.