Structural analysis of cyclamen seed xyloglucan oligosaccharides using cellulase digestion and spectroscopic methods

Abstract

Xyloglucan polymers have been isolated from cyclamen seeds and characterized by both liquid and CP-MAS 13C NMR spectroscopy. Treatment of the polysaccharides with cellulase from Trichoderma viride afforded XG oligomers which have been studied with both mass spectrometry and NMR spectroscopy. The repeating unit in the intact polymers and the most abundant hydrolysis product correspond to the Gal1 Xyl3 Glc4 (XXLG) fragment. However, detection of notable amounts of Xyl3 Glc4 (XXXG) and Gal2 Xyl3 Glc4 (XLLG) indicates that the galactose distribution in xyloglucan from cyclamen is irregular. FAB-MS analysis of a new derivative, prepared by forming the glycosamine of m-tetrafluoroethoxy aniline, has led to unambiguous sequence information for the XXLG oligomer.