Oligosaccharides obtained by enzymatic hydrolysis of birch kraft pulp xylan: analysis by capillary zone electrophoresis and mass spectrometry.
Neutral and acidic oligosaccharides were obtained from an unbleached birch kraft pulp by treatment with a Trichoderma reesei endoxylanase pI 9 and subsequently characterized using capillary zone electrophoresis (CZE) and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). The borate complexes of unsaturated acidic oligosaccharides having a 4-deoxy-beta-L-threo-hex-4-enopyranosyluronic acid (4 delta UA) residue linked to a beta-D-(1-->4)-xylooligosaccharide backbone were separated by CZE and detected by their UV absorption at 232 nm without prior derivatization. Pre-column derivatization with the chromophore 6-aminoquinoline (6-AQ) followed by CZE in alkaline borate buffer using detection based on absorption at 245 nm was used in the case of neutral xylosaccharides. Furthermore, MALDI-TOF-MS was employed to determine the molecular masses of both unsaturated and saturated acidic oligosaccharides. The acidic oligosaccharides released upon endoxylanase treatment of the birch kraft pulp were a (4 delta UA)-beta-D-xylotetraose, a (4 delta UA)-beta-D-xylopentaose, a (4-O-methyl-alpha-D-glucurono)-beta-D-xylotetraose, and a (4-O-methyl-alpha-D-glucurono)-beta-D-xylopentaose. Analysis after enzymatic hydrolysis with beta-xylosidase and alpha-glucuronidase from Trichoderma reesei strongly indicated that the uronic acid residue in these acidic oligosaccharides was linked to the D-xylose unit adjacent to the non-reducing D-xylose unit. The neutral xylosaccharides obtained after endoxylanase treatment of the pulp sample were D-xylose, beta-(1-4)-D-xylobiose and beta-(1-4)-D-xylotriose.
Rydlund
A
A
Swedish Pulp and Paper Research Institute, Stockholm, Sweden.
Dahlman
O
O
D002240:Carbohydrate Sequence; D019075:Electrophoresis, Capillary; D043364:Endo-1,4-beta Xylanases; D006868:Hydrolysis; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D010944:Plants / Q000737:chemistry*; D014990:Xylans / Q000737:chemistry*; D014995:Xylosidases
D009844:Oligosaccharides; D014990:Xylans; D014995:Xylosidases; D043364:Endo-1,4-beta Xylanases