Primary structure of the 2-O-methyl-alpha-L-fucose-containing side chain of the pectic polysaccharide, rhamnogalacturonan II.
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 alpha-linked by NMR analysis of a tetraglycosyl-glycerol fragment, [alpha-L-Arap-(1-->4)-beta-D-Galp-(1-->2)-alpha-L-AcefA-(1-->3)-beta-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 [triple bond] apiose): [see structure]. Data 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 beta-L-Araf and the alpha-L-Rhap residue attached to the O-3 of Arap, both of which are present on the wine nonasaccharide.
Glushka
John N
JN
Complex Carbohydrate Research Center, Department of Chemistry, The University of Georgia, 220 Riverbend Road, Athens, GA 30602-4712, USA.
Terrell
Mark
M
York
William S
WS
O'Neill
Malcolm A
MA
Gucwa
Angela
A
Darvill
Alan G
AG
Albersheim
Peter
P
Prestegard
James H
JH
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D005643:Fucose / Q000031:analogs & derivatives* / Q000737:chemistry*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry; D010368:Pectins / Q000737:chemistry*; D014920:Wine / Q000032:analysis
D009844:Oligosaccharides; C042492:rhamnogalacturonan II; D005643:Fucose; C076754:2-O-methylfucose; D010368:Pectins