Structural characterization of LbGpl from the fruits of Lycium barbarum L.

A water-soluble polysaccharide with a protein content of 3.75%, designated as LbGpl, was isolated from the fruit of Lycium barba rum L. The average molecular weight of LbGpl was 49.1 KDa determined by high performance gel permeation chromatography (HPGPC). Sugar composition analysis revealed that it was composed of Ara and Gal in a molar ratio of 5.6:1. The existence of O-glycopeptide bond in LbGpl was demonstrated by beta-elimination reaction. Structure of LbGpl was characterized based on monosaccharide composition, partial hydrolysis, methylation analysis and electrospray ionization mass spectrometer (ESI-MS). LbGpl was identified to be a highly branched polysaccharide with a backbone of -> 6) Galp(1 -> linked galactose substituted at 0-3 by galactosyl or arabinosyl groups. The branches were composed of (1 -> 4 3)-linked-Galp, (1 -> 4)-linked-Galp, (1 2)-linked-Araf and (1 -> 3)-linked-Araf, and arabinose was located at the terminal of the branches. (C) 2014 Elsevier Ltd. All rights reserved.