Primary structure of an N-glycosidic carbohydrate unit derived from Sophora japonica lectin.

The lectin isolated from Sophora japonica seeds is a glycoprotein which binds oligosaccharides with non-reducing terminal Gal beta(1----3/4)GlcNac beta 1----units. The carbohydrate moiety of the lectin is composed of fucose, xylose, mannose and N-acetylglucosamine. The major glycopeptide of the lectin, prepared by pronase digestion, was derivatized with fluorescein isothiocyanate, purified by PAGE and examined by exoglycosidase digestion as well as purified by gel filtration through Bio-Gel P6-DG and investigated by methylation analysis and 400-MHz 1H-NMR spectroscopy. The primary structure of the glycopeptide was established to be as follows. (Formula: see text). Structures similar to this containing a (beta 1-2)xylosyl substituent on the core beta-mannosyl residue and an inner core (alpha 1-3)fucosyl substituent seem to occur frequently in plant glycoproteins.