RAPID MOLECULAR-MASS AND STRUCTURAL DETERMINATION OF PLANT-CELL WALL-DERIVED OLIGOSACCHARIDES USING OFF-LINE HIGH-PERFORMANCE ANION-EXCHANGE CHROMATOGRAPHY MASS-SPECTROMETRY

A method has been developed for the rapid molecular mass determination and structural elucidation of mixtures of oligosaccharides derived fr om plant cell walls. The oligosaccharides were fractionated using gel permeation chromatography and 'analytical' high-performance anion-exch ange chromatography (HPAEC), neutralized, dried and the mixtures of el uent salt and oligosaccharides were per-O-acetylated directly, The der ivatized oligosaccharides were isolated by dissolution in dichlorometh ane and the salts were removed by aqueous partitioning, The per-O-acet ylated oligosaccharides were analysed using electrospray (ES) and matr ix-assisted laser desorption/ionization time of flight mass spectromet ry (MS), Exploiting the fact that acid-catalysed per-O-acetylation of oligosaccharides can be achieved even under the extremely salty condit ions that are found in post-column neutralized HPAEC fractions, and co mbining this derivatization step with off-line ESMS, allow rapid scree ning for molecular mass and thus yield information on the composition of the various oligosaccharides in these complex mixtures, Subsequent per-O-methylation of the per-O-acetylated, salt-free fractions and col lision-induced dissociation tandem mass spectrometric analysis was use d for additional sequence and branching determination of the oligosacc harides, (C) 1998 John Wiley & Sons, Ltd.