STRUCTURAL-ANALYSES OF XYLOGLUCAN HEPTASACCHARIDE BY THE POST-SOURCE DECAY FRAGMENT METHOD USING MATRIX-ASSISTED LASER DESORPTION IONIZATION TIME-OF-FLIGHT MASS-SPECTROMETRY/

In the post-source decay (PSD) fragment spectrum of a reduced xylogluc an heptasaccharide (XXXGol) from tamarind seeds, eleven sodium-adduct fragment ions and a precursor ion [M + Na](+) mere clearly observed by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). Each fragment ion interval corresponded t o the absence of unhydroxylose, unhydroglucose, and glucitol residues, indicating that PSD fragmentation cleavage in the sugar compound occu rred only at glycosidic linkages close to the oxygen atom of saccharid e ring members, and not in inner sugar ring bonds, The PSD fragment lo lls sere classified into two series, one involving the reducing end an d the other involving the non-reducing end, Structural information fro m both the reducing and non-reducing ends could therefore br simultane ously obtained from the measurement of the positive ion mode, Almost a ll the fragment ions from species larger than trisaccharide residues c ould be detected in this PSD fragment experiment, Such fragmentation i nformation will enable the structural determination of xyloglucan olig osaccharides.