Discrimination of Isomeric Fragment Ions Observed in Tandem Mass Spectra of Biantennary Oligosaccharides by Use of Selective Isotope Labeling

概要

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We report herein the first mass spectrometric analyses of isotopomers of a pyridylamino (PA)-derivatized biantennary oligosaccharide, in which one of two non-reducing terminal galactose residues is selectively enriched in 13C by an enzymatic reaction. By use of these isotopomeric PA-oligosaccharides, individual fragment ions observed in tandem mass spectra of MALDI-QIT-TOF-MS were unambiguously assigned. It was shown that the oligosaccharide ion that lacks the N-acetyllactosamine previously linked to the Manα1 →6 antenna dominates its isomeric counterpart ion. We propose that tandem mass spectrometric analyses of oligosaccharides isotopically labeled at a selected antenna would provide us with the basis of mechanisms of formation of glycosidic linkage fragment ions.
日本質量分析学会の論文
2004-10-01