Structural analysis of xyloglucan oligosaccharides by 1H-n.m.r. spectroscopy and fast-atom-bombardment mass spectrometry

Abstract

A method to determine rapidly the identities and proportions of the oligosaccharide repeating-units in plant cell-wall xyloglucans by 1D 1H-n.m.r. spectroscopy was developed. Six of the most commonly found xyloglucan oligosaccharide subunits (including three subunits that had not been fully characterized previously) were prepared by endo-(1----4)-beta-D-glucanase digestion of xyloglucans from various plant species. The oligosaccharides were reduced to the corresponding oligoglycosyl-alditols, purified, and characterized by glycosyl composition and linkage analysis, 1H-n.m.r. spectroscopy, and f.a.b.-mass spectrometry. Correlations between the 1H-n.m.r. spectra and the structures of the oligoglycosyl-alditols can be used to identify oligoglycosyl-alditols derived from xyloglucans of unknown structure. The identities and relative amounts of the oligosaccharide subunits of xyloglucans isolated from tamarind seed and rapeseed hulls were determined on this basis.