Influence of different glycosidic linkages on relative ion intensities in post-source decay fragmentation of a xyloglucan heptaoligosaccharide using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Post-source decay fragment analysis using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) has been applied to a highly branched xyloglucan heptasaccharide from tamarind seed. All fragment ions were produced by cleavage of the glycosidic linkages, including multi-site cleavages. The relative intensities of fragment ions that originated from one-site cleavages of the glycosidic linkages were much higher than those arising from two-site cleavages of the same kind of glycosidic linkage, which were in turn higher than those from three-site cleavages. The types of glycosidic linkages were an important factor which influenced the relative intensities of the MALDI-PSD (post-source decay) fragment ions. In the MALDI-PSD fragment spectrum of the xyloglucan heptasaccharide, the relative intensities of the ions produced by the cleavage of an alpha 1-6 glycosidic linkage were much higher than those arising from cleavage of the beta 1-4 glycosidic linkage.