Structural analysis of the xyloglucan from Phaseolus coccineus cell-walls using cellulase-derived oligosaccharides

Oligosaccharides, obtained by digestion of a xyloglucan from the cell walls of Phaseolus coccineus with cellulase, have been isolated by gel filtration. Oligosaccharides containing 2–6 residues accounted for ～57% of the hydrolysate, with larger oligosaccharides (d.p. ～10) and partially degraded xyloglucan accounting for ～32% of the polymer. The major glycosidic linkages were determined by methylation analysis. Methylated penta- and hexa-saccharide alditols were isolated by reverse-phase h.p.l.c. and characterised by e.i.-m.s. and f.a.b.-m.s. Methylated derivatives of the di-, tri-, and tetra-saccharide alditols were examined by g.l.c.-m.s. in the e.i. and c.i. modes. A structure based on these results is proposed.