Rapid Glass Wool Enrichment of Glycopeptides for MALDI-MS Analysis of Immunoglobulin G Glycosylation in COVID-19 Samples.

Glycosylation is the most common protein post-translational modification, affecting protein properties and functions. Abnormal variations in glycosylation are associated with diseases, e.g., coronavirus disease COVID-19. Matrix-assisted laser desorption/ionization mass spectrometry has been widely utilized for studying protein glycosylation, after proper purification of glycopeptides or glycans using hydrophilic interaction liquid chromatography (HILIC) or laboratory-synthesized hydrophilic materials. Here, glass wool tips were developed to enrich immunoglobulin G glycopeptides and applied in the analysis of COVID-19 patient samples as a proof-of-concept. A significant decrease in galactosylation was detected in the COVID-19 patient plasma sample compared to the reference sample. The tips developed in this work provided a cheap and simple enrichment alternative to commercial HILIC tips for studying protein glycosylation.