Characterization of TV-linked Glycan Structures Using Normal-phase Capillary LC-MALDI Tandem Mass Spectrometry

摘要

The addition of carbohydrates to proteins is one of the important post-translational modifications of proteins. Glycoproteins in many biological processes play a key role in immune defense, cell growth and cell-cell adhesion. In addition to aiding vital functionality to proteins, glycans also play an important role in protein stability. Glycoproteins often have very heterogeneous structures, due to the great diversity in the glycan moieties (known as glycoforms). Therefore, the full characterization of glycoproteins is a very difficult task, including the determination of glycan size, compositions, branching points and linkages of the carbohydrate monomers for each glycosylation sites. The structural characterization of glycans released from glycoproteins is extremely challenging and multiple techniques are often required for complete characterization. The pool of glycans released by either chemical or enzymatic cleavages of glycoproteins is usually analyzed by high-performance anion-exchange chromatography, followed by the addition of chro-mophore at the reducing terminus of glycans. Mass spectrometry has extensively used for detailed characterization of N-linked glycans, including monosaccharide composition, as well as sequence, branching, and sometimes linkage information by tandem mass spectrometry.