Primary structure of the 2-O-methyl-α-l-fucose-containing side chain of the pectic polysaccharide, rhamnogalacturonan II Original Research Article

A 2-O-methylfucosyl-containing heptasaccharide was released from red wine rhamnogalacturonan II (RG-II) by acid hydrolysis of the glycosidic linkage of the aceryl acid residue (AceA) and purified to homogeneity by size-exclusion and high-performance anion-exchange chromatographies. The primary structure of the heptasaccharide was determined by glycosyl-residue and glycosyl-linkage composition analyses, ESIMS, and by 1H and 13C NMR spectroscopy. The NMR data indicated that the pyranose ring of the 2,3-linked l-arabinosyl residue is conformationally flexible. The l-Arap residue was confirmed to be α-linked by NMR analysis of a tetraglycosyl-glycerol fragment, [α-l-Arap-(1→4)-β-d-Galp