Hybrid Mass Spectrometric Approaches Expose the Diverse Proteoform Profiles of Serum Glycoproteins

Protein glycosylation is a complex post-translation modification due to structural diversity of glycans. The subtle changes in glycan structures can potentially affect the protein’s biologically function. The research in this thesis mainly focuses on studying serum protein glycosylation by using two different mass spectrometry (MS) approaches; native MS and glycopeptide-centric analysis MS. High-resolution native MS has been applied for the in-depth characterization of intact proteins, including the comprehensive evaluation of glycoproteoform heterogeneity and discovery of sequence variants. Peptide-centric MS analysis has been used to complement native MS data and characterize large numbers of glycoproteins in complex biological mixtures. To this end, glycopeptides have been enriched by a novel high-throughput method prior to the MS analysis in order to reduce sample complexity and increase glycopeptide sensitivity.