Both, P. et al. Nat. Chem. 6, 65–74 (2014).

Though protein glycosylation is known to play an important role in many biological processes, glycan and glycopeptide structures remain very challenging to characterize owing to their diverse and heterogeneous nature. Although mass spectrometry has been a considerably useful technology for obtaining structural information about complex mixtures of glycoconjugates, a remaining challenge has been the inability to distinguish epimers (stereoisomers that differ only by a single chiral center). Both et al. now report a method using ion-mobility mass spectrometry (IM-MS) that is able to distinguish epimers on the basis of the unique ion-mobility drift times of the monomers generated by collision-induced dissociation. They further showed that a series of epimeric disaccharides could be successfully analyzed by the IM-MS technique, which suggests that the approach could be used generally for glycan sequencing.