Structural characterization of the glycan part of glycoconjugate LbGp2 from Lycium barbarum L.

A glycoconjugate with pronounced immunoactivity, designated as LbGp2, was isolated from the fruit of Lycium barbarum L. and purified to homogeneity by gel-filtration. Its carbohydrate content is up to 90.71% composed of Ara, Gal and amino acids. The molecular weight is 68.2 kDa as determined by size exclusive chromatography (SEC). The complete structure of the repeat unit of the glycan of LbGp2 was elucidated based on glycosidic linkage analysis, total acid hydrolysis, partial acid hydrolysis, 1H and 13C NMR spectroscopy. According to the experiments, the glycan possesses a backbone consisting of (1-->6)-beta-galactosyl residues, about fifty percent of which are substituted at C-3 by galactosyl or arabinosyl groups and the major nonreducing end being made of Ara (1 -->.