Electron detachment dissociation of glycosaminoglycan tetrasaccharides.

The first application of electron detachment dissociation (EDD) to carbohydrates is presented. The structural characterization of glycosaminoglycan (GAG) oligosaccharides by mass spectrometry is a longstanding problem because of the lability of these acidic, polysulfated carbohydrates. Doubly-charged negative ions of four GAG tetrasaccharides are examined by EDD, collisionally activated dissociation (CAD), and infrared multiphoton dissociation (IRMPD). EDD is found to produce information-rich mass spectra with both cross ring and glycosidic cleavage product ions. In contrast, most of the product ions produced by CAD and IRMPD result from glycosidic cleavage. EDD shows great potential as a tool for locating the sites of sulfation and other modifications in glycosaminoglycan oligosaccharides.