Oligosaccharide Structures Studied by Hydrogen−Deuterium Exchange and MALDI-TOF Mass Spectrometry

Hydrogen-deuterium exchange matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (HX-MALDI-TOF MS) is reported for the determination of exchangeable protons in diverse oligosaccharide and glycoconjugate structures. The method has broad application for determining carbohydrate structure and conformation and to the study of carbohydrate-ligand interactions. The proton exchange process has been optimized to maximize the forward deuterium exchange and to suppress the well-known problem of back-exchange and is suitable for the analysis of all exchangeable proton types in carbohydrates. This has been validated for several diverse carbohydrate structures, including series of malto- and xylopyranose oligosaccharides; alpha- and beta-cyclodextrins; a nonreducing tetrasaccharide, stachyose; an N-acetylamide-containing oligosaccharide, chitotetraose; and a tertiary hydroxyl-containing antibiotic glycoconjugate, erythromycin.