Structure of neutral branched xylooligosaccharides produced by xylanase from in situ reduced hardwood xylan

Two neutral oligosaccharides from in situ reduced hardwood xylan were isolated and completely characterized by methylation analysis and 2D NMR spectroscopy (COSY, HOHAHA, HMQC, HMQC–TOCSY, NOESY, and HMBC techniques). The oligosaccharides are the xylotetrasaccharide, 4-O-methyl-α-d-glucopyranosyl-(1→2)-d-xylotriose and the xylopentasaccharide 4-O-methyl-α-d-glucopyranosyl-(1→2)-d-xylotetraose. From reactivities observed with these compounds, the mode of action of β-xylanase is described.