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Structural assignment of permethylated oligosaccharide subunits using sequential tandem mass spectrometry
N Viseux1, E de Hoffmann, B Domon
1Laboratoire de Spectrométrie de Masse, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.
Analytical Chemistry
|December 16, 1998
Summary
Sequential tandem mass spectrometry (MSn) on quadrupole ion traps simplifies carbohydrate structure analysis. This method allows unambiguous structural assignment of complex oligosaccharides by analyzing collision-induced dissociation patterns.
Area of Science:
- Analytical Chemistry
- Glycobiology
- Mass Spectrometry
Background:
- Oligosaccharides play crucial roles in biological processes.
- Elucidating the complex structures of oligosaccharides is challenging.
- Per-methylation and mass spectrometry are key techniques in carbohydrate analysis.
Purpose of the Study:
- To systematically study the sequential tandem mass spectrometry (MSn) capabilities of quadrupole ion trap instruments for oligosaccharide structural elucidation.
- To establish rules for structural assignment of carbohydrates using MSn fragmentation patterns.
- To demonstrate the utility of MSn for characterizing unknown carbohydrate structures.
Main Methods:
- Electrospray ionization (ESI) followed by collision-induced dissociation (CID) in a quadrupole ion trap.
- Sequential tandem mass spectrometry (MSn) for fragmenting permethylated oligosaccharides.
- 18O-labeling experiments to corroborate fragmentation rules.
- Comparison of CID spectra with reference compounds for structural assignment.
- CD3 labeling for characterizing specific oligosaccharide subunits.
Main Results:
- Protonated permethylated oligosaccharides yield predictable mass spectra under CID.
- MSn provides information on sequence, branching, and interglycosidic linkages through glycosidic bond cleavage.
- Established simple rules for carbohydrate structural assignment based on fragmentation patterns.
- Demonstrated unambiguous structural characterization of unknown carbohydrates by spectral matching.
- Successfully applied MSn to characterize fucosylated and sialylated oligosaccharide subunits.
Conclusions:
- Quadrupole ion trap MSn is a powerful technique for elucidating complex carbohydrate structures.
- The method allows for the virtual degradation of large carbohydrates into smaller, analyzable fragments.
- MSn provides a basis for the routine structural characterization of biologically important oligosaccharides.