The structure of rhamnogalacturonen II from the cell wall of suspension-cultured poplar cells

Rhamnogalacturonan II (RG-II) was isolated from the pectin of the cell wall of suspension-cultured poplar (Populus Alba L.) cells. The PC-II consisted of rhamnosyl, fucosyl, arabinosyl, xylosyl, galactosyl, glucosyl, galacturonic acid, glucuronic acid residues and seldom-observed sugars such as 2-O-methyl-L-fucose, 2-O-methyl-D-xylose, apiose {3-C-(hydroxymethyl)-D-glycero-aldotetrose}, aceric acid (3-C-carboxy-5-deoxy-L-xylose) and 3-deoxy-D-manno-2-octulosonic acid (KDO). The glycosyl residues were interconnected by more than 20 different glycosyl linkages. The structures of the oligosaccharide fragments of the RG-II generated by partial hydrolysis with acid were determined. Novel oligosaccharides having high molecular weights (> m/z 2000) were detected besides the same oligosaccharides found in the partial hydrolysis products of sycamore RG-II. Glycosyl linkage composition analysis suggested that the oligosaccharides contained the repeats of known partial structures of RG-II.