Hydrophilic interaction chromatography coupled to ultraviolet photodissociation affords identification, localization, and relative quantitation of glycans on intact glycoproteins

Protein glycosylation is implicated in a wide array of diseases, yet glycoprotein analysis remains elusive owing to the extreme heterogeneity of glycans including microheterogeneity at the same amino acid residue (glycosite). Top-down mass spectrometry (MS) allows precise identification and localization of glycans on intact proteins, and coupling top-down MS with chromatography allows time-resolved characterization of glycoforms. Here, we couple ultraviolet photo-dissociation (UVPD) to hydrophilic interaction chromatography (HILIC) to advance the characterization of glycoproteins ranging from 15-34 kDa, offering site localization of glycans, providing sequence coverages up to 93% and relative quan-titation of individual glycoforms.