Structural characterization of two oligosaccharide fragments formed by the selective cleavage of rhamnogalacturonan II: evidence for the anomeric configuration and attachment sites of apiose and 3-deoxy-2-heptulosaric acid.
Evidence for the anomeric configurations and attachment sites of 3-deoxy-D-lyxo-2-heptulosaric acid (DHA) and apiosyl residues has been obtained through the characterization of two oligoglycosyl fragments isolated from rhamnogalacturonan II (RG-II). One of the oligoglycosyl fragments, a pentaglycosyl aldonic acid generated by Smith degradation of RG-II, was composed of four D-galactopyranosyluronic acid residues, a DHA residue, and a threonic acid residue (derived from a D-galactopyranosyluronic acid residue). The structural analysis of the pentaglycosyl aldonic acid established the beta-D-configuration for the DHA residue. Furthermore, it established that a previously identified diglycosyl side chain, 5-O-(beta-L-arabinofuranosyl)-DHA was directly attached to O-3 of a D-galactopyranosyluronic acid residue in the backbone of RG-II. The second oligoglycosyl fragment, a peralkylated diglycosyl hex-1-enitol, was generated by hex-5-enose degradation of permethylated and carboxyl-reduced RG-II. The structure of the peralkylated diglycosyl hex-1-enitol, beta-L-Rhap-(1----3')-beta-D-Apif-(1----5)-hex-1-enitol++ +, was determined by a combination of glycosyl-linkage composition analysis and n.m.r. spectroscopy. The n.m.r. data indicated the beta-configuration for the D-apiosyl residue. The isolation and characterization of the diglycosyl hex-1-enitol also established that a previously identified heptaglycosyl side chain was directly attached to O-2 of a D-galactopyranosyluronic acid in the backbone of RG-II.
Puvanesarajah
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Complex Carbohydrate Research Center, University of Georgia, Athens 30602.
Darvill
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Albersheim
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D002087:Butyrates / Q000737:chemistry; D002240:Carbohydrate Sequence; D002473:Cell Wall / Q000737:chemistry*; D002478:Cells, Cultured; D003837:Deoxy Sugars / Q000737:chemistry / Q000378:metabolism*; D005960:Glucosides / Q000737:chemistry; D008351:Mannans / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D010368:Pectins / Q000737:chemistry / Q000378:metabolism*; D010429:Pentoses / Q000737:chemistry; D013400:Sugar Acids / Q000737:chemistry; D013402:Sugar Alcohols / Q000737:chemistry; D014197:Trees / Q000737:chemistry*
D002087:Butyrates; D003837:Deoxy Sugars; D005960:Glucosides; D008351:Mannans; D009844:Oligosaccharides; D010429:Pentoses; D013400:Sugar Acids; D013402:Sugar Alcohols; C065836:rhamnan; C060021:3-deoxy-2-heptulosaric acid; D010368:Pectins; C004983:apiose; C011369:threonic acid; C003181:polygalacturonic acid