Structural characterization of red wine rhamnogalacturonan II

✍ Scribed by Patrice Pellerin; Thierry Doco; Stéphane Vida; Pascale Williams; Jean-Marc Brillouet; Malcolm A. O'Neill

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 724 KB
• Volume: 290
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(96)00139-5

✦ Synopsis

The pectic polysacchatide rhamnogalacturonan II (RG-II), which accounts for ~ 20% of the ethanol-precipitable polysacchatides in red wine, has been isolated from wine polysaccharides by anion-exchange chromatography. Four fractions enriched with RG-II were obtained and the RG-II then purified to homogeneity by Concanavalin A affinity and size-exclusion chromatographies. The glycosyl-residue compositions of the four RG-IIs are similar; all the RG-IIs contain the monosaccharides (apiose, 2-O-methyl-L-fucose, 2-O-methyl-D-xylose, Kdo, Dha, and acetic acid) that are diagnostic of RG-II. The glycosyl-linkages of the neutral and acidic sugars, including acetic acid, were determined simultaneously by GC-EIMS analysis of the methylated alditol acetates generated from per-O-methylated and carboxyl-reduced RG-II. Two of the RG-IIs contain boron, most likely as a borate di-ester that cross-links two molecules of RG-II together to form a dimer. The dimer contains 3'-and 2,3,3'-linked apiosyl residues whereas the monomer contains only 3'-linked apiosyl residues which suggests that the borate di-ester is located on at least one of the apiosyl residues of RG-II. Although the wine RG-IIs all have similar structures they are not identical since they differ in the length and degree of methyl-estetification of the RG-II backbone