INFLUENCE OF STEREOISOMERIC GLUCOSE, GALACTOSE AND MANNOSE RESIDUES ON FRAGMENTATION AT THEIR GLYCOSIDIC LINKAGES IN POST-SOURCE DECAY FRAGMENT ANALYSES FOR OLIGOSACCHARIDES USING MATRIX-ASSISTED-LASER-DESORPTION IONIZATION TIME-OF-FLIGHT MASS-SPECTROMETRY/

The isomeric sugar branched beta-cyclodextrin (CD) derivatives (Glc-be ta CD, Gal-beta CD, and Man-beta CD) were analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectromet ry. In the MALDI post-source decay (PSD) fragmentation of Glc-beta CD, Gal-beta CD and Man-beta CD, the fragment ions of [M-Glc](+), [M-Gal] (+) and [M-Man](+) were produced by the one-site cleavage of the alpha 1-6 glycosidic linkage at the branch (Y-type fragmentation). The abun dances of [M-Glc](+) and [M-Gal](+) ions were much higher than that of [M-Man](+), These results indicated that Glc-beta CD and Gal-beta CD were distinguishable from Man-beta CD, and that Y-type fragmentations of the branched glycosidic linkage at the glycosyl donors of alpha-D-G lc and alpha-D-Gal were more predominant than that at the glycosyl don or of alpha-D-Man by MALDI-PSD fragment analysis. It was concluded tha t the abundances of PSD fragment ions depended on the stereochemistry of the glycosyl donors in the cleavage of the glycosidic linkage of th e oligosaccharides in MALDI-TOF mass spectra, (C) 1998 John Wiley & So ns, Ltd.