A new fluorescent tag for labeling of saccharides

Potential aldehyde groups of N-acetylglucosamine and its di- and tri-saccharides were coupled with 7-amino-4-methylcoumarin (AMC) by reductive amination in the presence of sodium cyanoborohydride. The products were purified by silica gel chromatography. Acid hydrolysis and digestion with glycosidases gave the expected products. One picomole of the sugar-AMC complexes could be detected after thin-layer chromatography by fluorescence under uv light. The sensitivity of the detection of the fluorescently labeled carbohydrates is comparable to that of NaB3H4 labeling.