MALDI mass spectrometry analysis of N-glycans through DMTMM-mediated benzylamidation and Girard's reagent P labeling

Abstract

Glycosylation is one of the major post-translational modifications of proteins and plays important roles in diverse biological processes, including cell signaling and recognition. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has been widely used to analyze glycans formed through glycosylation because it generates mainly singly charged ions and offers relatively high ionization efficiency for glycans. In this study, we present a method for MALDI-MS-based N-glycan analysis with 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM)-mediated stabilization of sialic acids and permanent cationic labeling of the glycan reducing ends. This method allows the sensitive measurement of intact N-glycans released from glycoproteins and may contribute to the characterization of biotherapeutic glycosylation in the pharmaceutical industry.