Gas-Phase Hydrogen/Deuterium Exchange for Distinguishing Isomeric Carbohydrate Ions

Abstract

The structural diversity of carbohydrates presents a major challenge for glycobiology and the analysis of glycoconjugates. Mass spectrometry has become a primary tool for glycan analysis thanks to its speed and sensitivity, but the information content regarding the glycan structure of protonated glycoconjugates is hindered by the inability to differentiate linkage and stereoisomers. Here, we examine a variety of protonated carbohydrate structures by gas-phase hydrogen/deuterium exchange (HDX) to discover that the exchange rates are distinct for isomeric carbohydrates with even subtle structural differences. By incorporating an internal exchange standard, HDX could effectively distinguish all linkage and stereoisomers that were examined and presents a mass spectrometry-based approach for glycan structural analysis with immense potential.