Glycoproteins are becoming increasingly relevant in therapeutics, including tissue plasminogen activator for
the treatment of myocardial infarction and strokes, erythropoietin for anemia and various monoclonal antibody–based
treatments for cancer. Protein N- and O-glycosylation is perhaps the most crucial and immensely complex posttranslational
modification that proteins undergo, and its characterization presents a major challenge. This review will discuss current
techniques for the characterization of glycoproteins, with a focus on therapeutic glycoproteins where available. The
crucial analytical techniques, such as high-performance liquid chromatography (HPLC), capillary electrophoresis (CE),
and mass spectrometry (MS) will be described, alongside the necessary chemical labeling methods for sensitive detection.
The well-established chemical and enzymatic methods for oligosaccharide release from proteins will be discussed, as will
more modern methods based on exhaustive protein hydrolysis with non-specific proteases.