Isolation and structural characterization of β-d-glucosyluronic acid and 4-O-methyl β-d-glucosyluronic acid-containing oligosaccharides from the cell-wall pectic polysaccharide, rhamnogalacturonan I
✍ Scribed by Jinhua An; Malcolm A. O'Neill; Peter Albersheim; Alan G. Darvill
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 698 KB
- Volume
- 252
- Category
- Article
- ISSN
- 0008-6215
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✦ Synopsis
Rhamnogalacturonan I (RG-I), a pectic polysaccharide isolated from the walls of suspension-cultured sycamore cells, was shown by glycosyl-residue composition analysis to contain D-glucosyluronic acid (GlcpA) residues (1 mol%) and 4-O-methyl-D-glucosyluronic acid (4-O-Me-GlcpA) residues (0.5 mol%). These monosaccharides were shown, by glycosyl-linkage analysis, to be present in RG-I as terminal nonreducing residues. The glycosyl sequences containing GlcpA and 4-O-Me-GlcpA were determined by structurally characterizing the acidic oligosaccharides released by partial acid hydrolysis of RG-I. Six acidic oligosaccharides were purified by semipreparative high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and characterized by glycosyl-residue and glycosyl-linkage composition analyses, GLC-CIMS, GLC-EIMS, electrospray MS (ESMS), and 1H NMR spectroscopy. We propose that three of the acidic oligosaccharides characterized, 4-O-Me-beta-D-GlcpA-(1-->6)-D-Gal, beta-D-GlcpA-(1-->6)-D-Gal, and beta-D-GlcpA-(1-->4)-D-Gal, originate from the galactosyl-containing side chains of RG-I. The three other acidic oligosaccharides characterized, alpha-D-GalpA-(1-->2)-L-Rha, alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-->4)-alpha-D-GalpA+ ++-(1-->2)-alpha-L-Rha, and alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-->4)-alpha-D-GalpA+ ++-(1-->2)-alpha-L- Rhap-(1-->4)-alpha-D-GalpA-(1-->2)-alpha-L-Rha, were generated by partial hydrolysis of the RG-I backbone. No evidence was obtained for the presence of galactosyluronic acid in the side chains of RG-I.(ABSTRACT TRUNCATED AT 250 WORDS)