Characterization of O-acetyl-(4-O-methylglucurono)xylan isolated from birch and beech

Abstract The structures of water-soluble birch and beech xylans, extracted from holocellulose using dimethyl sulfoxide, were determined employing 1 H and 13 C 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-α- d -Glc p A-(1→2)][3- O -Ac]-β- d -Xyl p -(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.