STRUCTURE OF L-ARABINO-D-GALACTAN-CONTAINING GLYCOPROTEINS FROM RADISH LEAVES

Article abstract of DOI:10.1016/0008-6215(84)85039-9

Two L-arabino-D-galactan-containing glycoproteins having a potent inhibitory activity against eel anti-H agglutinin were isolated from the hot saline extracts of mature radish leaves and characterized to have a similar monosaccharide composition that consists of L-arabinose, D-galactose, L-fucose, 4-O-methyl-D-glucuronic acid, and D-glucuronic acid residues.The chemical structure features of the carbohydrate components were investigated by carboxyl group reduction, methylation, periodate oxidation, partial acid hydrolysis, and digestion with exo- and endo-glycosidases, which indicated a backbone chain of (1->3)-linked β-D-galactosyl residues, to which side chains consisting of α-(1->6)-linked D-galactosyl residues were attached.The α-L-arabinofuranosyl residues were attached as single nonreducing groups and as O-2- or O-3-linked residues to O-3 of the β-D-galactosyl residues of the side chains.Single α-L-fucopyranosyl end groups were linked to O-2 of the L-arabinofuranosyl residues, and the 4-O-methyl-β-D-glucopyranosyluronic acid end-groups were linked to D-galactosyl residues.The O-α-L-fucopyranosyl-(1->2)-α-L-arabinofuranosyl end-groups were shown to be responsible for the serological, H-like activity of the L-arabino-D-galactan glycoproteins.Reductive alkaline degradation of the glycoconjugates showed that a large proportion of the polysaccharide chains is conjugated with the polypeptide backbone through a 3-O-D-galactosylserine linkage.