title: Characterization of an acetylated heteroxylan from Eucalyptus globulus Labill.
abstract: A heteroxylan was isolated from Eucalyptus globulus wood by extraction of peracetic acid delignified holocellulose with dimethyl sulfoxide. Besides (1-->4)-linked beta-D-xylopyranosyl units of the backbone and short side chains of terminal (1-->2)-linked 4-O-methyl-alpha-D-glucuronosyl residues (MeGlcA) in a 1:10 molar ratio, this hemicellulose contained galactosyl and glucosyl units attached at O-2 of MeGlcA originating from rhamnoarabinogalactan and glucan backbones, respectively. About 30% of MeGlcA units were branched at O-2. The O-acetyl-(4-O-methylglucurono)xylan showed an acetylation degree of 0.61, as determined by 1H NMR spectroscopy, and a weight-average molecular weight (M(w)) of about 36 kDa (P=1.05) as revealed from size-exclusion chromatography (SEC) analysis. About half of the beta-D-xylopyranosyl units of the backbone were found as acetylated moieties at O-3 (34 mol%), O-2 (15 mol%) or O-2,3 (6 mol%). Practically, all beta-D-xylopyranosyl units linked at O-2 with MeGlcA residues were 3-O-acetylated (10 mol%).
authors.affiliation: CICECO and Department of Chemistry, University of Aveiro, P 3810-193, Aveiro, Portugal. dmitry@dq.ua.pt
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Evtuguin
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Tomás
authors.forename: Artur M S
authors.initials: AM
authors.lastname: Silva
authors.forename: Carlos Pascoal
authors.initials: CP
authors.lastname: Neto
mesh_terms: D000107:Acetylation; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002850:Chromatography, Gel / Q000379:methods; D005052:Eucalyptus / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D015394:Molecular Structure; D014934:Wood; D014990:Xylans / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D014990:Xylans