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Abstract
Glycosaminoglycans (GAGs) are complex linear carbohydrates that participate in a broad range of biological processes. Their structural analysis is challenging, and there has been considerable research into tandem mass spectrometry (MS/MS) approaches. Electron activation methods such as electron detachment dissociation (EDD) produce glycosidic fragments and an abundance of cross-ring fragmentation, but this approach is confined to FTICR mass spectrometers. EDD has been shown to accurately identify sulfate position of GAG oligosaccharides and can distinguish C-5 uronic acid stereochemistry in some cases. We have investigated other electronic excitation methods that can produce EDD-like fragmentation behavior. Charge transfer dissociation (CTD), and ultraviolet photodissociation (UVPD) and negative electron transfer dissociation (NETD) have great potential for the analysis of sulfated GAGs. For each method, the location of sulfate modifications can be assigned. Additionally, C-5 uronic acid stereochemistry could be determined when epimer pairs were tested. The advancement of electron based activation methods allows for full GAG sequencing in a variety of instrumentation.