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Abstract
Glycosaminoglycans (GAGs) are a diverse group of linear, acidic, variably modified polysaccharides. Determining the sites of modification is of significant interest as these sites of modification are believed to influence the biological function of GAGs. However, the structural characterization of sulfated glycosaminoglycans has been a longstanding problem due to the lability of these oligosaccharides. In this work, the application of electron detachment dissociation (EDD) Fourier transform mass spectrometry (FTMS) to the analysis of sulfated GAGs is presented. EDD produces more abundant glycosidic and cross-ring cleavages for GAG oligosaccharides than does other more conventional ion activation methods, allowing sites of modification to be determined with a single tandem mass spectrometry experiment. EDD can also distinguish the epimers glucuronic acid (GlcA) and iduronic acid (IdoA) from each other in heparan sulfate oligosaccharides. The influence of the charge state on EDD, and characterization of products that arise from electron induced dissociation (EID) are also presented. Overall, EDD is shown to be a powerful tool for characterization of sulfated GAGs.