NMR structural determination of dissolved O-acetylated galactoglucomannan isolated from spruce thermomechanical pulp.
Water-soluble O-acetylated galactoglucomannan (GGM) isolated from spruce thermomechanical pulp (TMP) by hot-water extraction was characterized by 1D and 2D (homo- and heteronuclear) NMR analysis. The backbone was found to consist of (1-->4)-linked mannopyranosyl and glucopyranosyl units in a ratio of 10:1.9-2.6. The mannopyranosyl units were acetylated at C-2 and C-3 with a degree of acetylation around 0.28-0.37 as determined by NMR. A slightly larger amount of 2-O-acetylated mannopyranosyl was detected when compared to the 3-O-acetylated component. Approximately every 10th mannopyranosyl unit was substituted at C-6 by a single alpha-galactopyranosyl unit. Fine structure determination based on sequence-specific chemical shift variations showed that the distribution of glycosyl residues is random. Small amounts of other minor polysaccharide species including xylans and galactans could also be identified by NMR.
Hannuksela
Tea
T
Process Chemistry Group, Abo Akademi University, Porthaninkatu 3, FIN-20500, Turku/Abo, Finland. tea.hannuksela@abo.fi
Hervé du Penhoat
Catherine
C
D000107:Acetylation; D005690:Galactose / Q000032:analysis / Q000737:chemistry; D005947:Glucose / Q000032:analysis / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008351:Mannans / Q000737:chemistry* / Q000302:isolation & purification*; D008358:Mannose / Q000032:analysis / Q000737:chemistry; D028222:Picea / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry
D008351:Mannans; D010936:Plant Extracts; C443804:galactoglucomannan; D005947:Glucose; D008358:Mannose; D005690:Galactose