Structural characterization of novel L-galactose-containing oligosaccharide subunits of jojoba seed xyloglucans

Jojoba seed xyloglucan was shown to be a convenient source of biologically active xyloglucan oligosaccharides that contain both L-and D-galactosyl residues EE. Zablackis et al., Science, 272 (1996) 1808-1810]. Oligosaccharides were isolated by liquid chromatography of the mixture of oligosaccharides generated by treating jojoba seed xyloglucan with a beta-(1 --> 4)-endoglucanase. The purified oligosaccharides were reduced with NaBH4, converting them to oligoglycosyl alditol derivatives that were structurally characterized by a combination of mass spectrometry and 2-dimensional NMR spectroscopy. This analysis established that jojoba xyloglucan oligosaccharides contain the novel side-chain [alpha-L-Galp-(1 --> 2)-beta-D-Galp-(1 --> 2)-alpha-D-Xylp-(1 --> 6)-], which is structurally homologous to the fucose-containing side-chain [alpha-L-Fucp-(1 --> 2)-beta-D-Galp-(1 --> 2)-alpha-D-Xylp-(1 --> 6)-] found in other biologically active xyloglucan oligosaccharides. (C) 1997 Elsevier Science Ltd.