Structures of sugar chains of water-soluble glycoproteins in developing castor bean cotyledons.

The structures of sugar chains from the water-soluble glycoproteins in developing castor beans have been identified. The structural analyses were done by a fluorescence method combined with exoglycosidase digestions and 1H-NMR spectroscopy. The identified structures fell into two categories; one was an oligomannose-type, the other xylomannose-type or xylose-containing type. Among these oligosaccharides, Man3Fuc1Xyl1GlcNAc2 (M3FX; 38%) and Man6GlcNAc2 (M6B; 22%) were the major structures. The higher mannose-content oligosaccharides (Man8-7GlcNAc2) were only 4.1%, and the further-modified structures (GNM3FX, M2FX) than M3FX were 22% of the total.