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

2003; Elsevier BV; Volume: 338; Issue: 4 Linguagem: Inglês

10.1016/s0008-6215(02)00461-5

1873-426X

John Glushka, Mark Terrell, William S. York, Malcolm A. O’Neill, Angela L. Gucwa, Alan G. Darvill, Peter Albersheim, James H. Prestegard,

Polysaccharides Composition and Applications

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-(1→2)-α-l-AcefA-(1→3)-β-l-Rhap-(1→3)-Gro], generated by Smith degradation of RG-II. Our data together with the results of a previous study,1 establish that the 2-O-Me Fuc-containing nonasaccharide side chain of wine RG-II has the structure (Api≡apiose):Download : Download full-size imageData are presented to show that in Arabidopsis RG-II the predominant 2-O-MeFuc-containing side chain is a mono-O-acetylated heptasaccharide that lacks the non-reducing terminal β-l-Araf and the α-l-Rhap residue attached to the O-3 of Arap, both of which are present on the wine nonasaccharide.