Analysis of glycoprotein heterogeneity by capillary electrophoresis and mass spectrometry

Glycosylation is a complex posttranslational modification that can result in extensive heterogeneity for recombinant glycoproteins produced by eukaryotic systems. The carbohydrate moiety of a recombinant glycoprotein may affect the immunogenicity, half-life, bioactivity, and stability of a potential therapeutic product. Regulatory authorities such as the US Food and Drug Administration demand increasingly sophisticated carbohydrate analysis to ensure product characterization, batch-to-batch consistency, and stability. The advent of new technologies for analysis of biopolymers by capillary electrophoresis and mass spectrometry has revolutionized strategies for recombinant protein characterization. In particular, recent advances in matrix-assisted laser desorption/ionization and electrospray ionization mass spectrometry now permit relatively rapid and detailed assessment of glycoprotein and oligosaccharide structure. In this article, we describe some applications of capillary electrophoresis and mass spectrometry to monitor the glycosylation associated with a model recombinant glycoprotein, human interferon-gamma.