Characterization of O-acetyl-(4-O-methylglucurono)xylan isolated from birch and beech.
The structures of water-soluble birch and beech xylans, extracted from holocellulose using dimethyl sulfoxide, were determined employing 1H and 13C NMR spectroscopy together with chemical analysis. These polysaccharides were found to be O-acetyl-(4-O-methylglucurono)xylans containing one 4-O-methylglucuronic acid substituent for approximately every 15 D-xylose residues. The average degree of acetylation of the xylose residues in these polymers was 0.4. The presence of the structural element -->4)[4-O-Me-alpha-D-GlcpA-(1-->2)][3-O-Ac]-beta-D-Xylp-(1--> was demonstrated. Additional acetyl groups were present as substituents at C-2 and/or C-3 of the xylopyranosyl residues. Utilizing size-exclusion chromatography in combination with mass spectroscopy, the weight-average molar masses (and polydispersities) were shown to be 8000 (1.09) and 11,100 (1.08) for birch and beech xylan, respectively.
Teleman
Anita
A
Swedish Pulp and Paper Research Institute, STFI, Box 5604, SE-114 86, Stockholm, Sweden. anita.teleman@stfi.se
Tenkanen
Maija
M
Jacobs
Anna
A
Dahlman
Olof
O
D000107:Acetylation; D029662:Betula / Q000737:chemistry*; D002850:Chromatography, Gel / Q000379:methods; D029964:Fagus / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D014990:Xylans / Q000302:isolation & purification*; D014994:Xylose
C456725:O-acetyl-(4-O-methylglucurono)xylan; D014990:Xylans; D014994:Xylose