title: Identification of the acidic degradation products of hexenuronic acid and characterisation of hexenuronic acid-substituted xylooligosaccharides by NMR spectroscopy.
abstract: A 4-O-methylglucuronoxylan was converted into a hexenuronoxylan at high temperature and alkalinity similar to the conditions used during kraft pulping. The hexenuronoxylan was hydrolysed with enzymes, and acidic xylooligosaccharides were separated from the hydrolysate by anion-exchange and size-exclusion chromatography. The primary structure of the two main hexenuronic acid-substituted xylooligosaccharides (a tetramer and a pentamer) was determined by two-dimensional 1H and 13C NMR spectroscopy. The 4-deoxy-hexenuronic acid is not stable under the acid hydrolysis step of conventional carbohydrate analysis. Here, we have identified the acidic degradation products of 4-deoxy-hexenuronic acid by NMR spectroscopy. Two degradation pathways were observed, both resulting in a furan derivative.
authors.affiliation: Technical Research Centre of Finland, Finland.
authors.forename: A
authors.initials: A
authors.lastname: Teleman
authors.forename: T
authors.initials: T
authors.lastname: Hausalo
authors.forename: M
authors.initials: M
authors.lastname: Tenkanen
authors.forename: T
authors.initials: T
authors.lastname: Vuorinen
mesh_terms: D002240:Carbohydrate Sequence; D002852:Chromatography, Ion Exchange; D006603:Hexuronic Acids / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008031:Lignin; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009844:Oligosaccharides / Q000737:chemistry* / Q000302:isolation & purification; D014934:Wood; D014990:Xylans / Q000737:chemistry*; D014994:Xylose / Q000031:analogs & derivatives
chemical_list: D006603:Hexuronic Acids; D009844:Oligosaccharides; D014990:Xylans; C095263:hexenuronic acid; C038910:glucuronoxylan; C076151:Kraft lignin; D008031:Lignin; D014994:Xylose