Protein carbohydrate analysis: Gel-Based staining, liquid chromatography, mass spectrometry, and microarray screening

Carbohydrate modification of proteins and lipids serves to functionally "fine-tune" these molecules, which are involved in a wide variety of physiological and pathogenic processes through specific biological interactions. Therefore, errors in glycosylation have severe implications and have been associated with many common diseases such as cancer and diabetes. Carbohydrates have historically been desirable targets for drug invention. Recent advances in detection and analysis of carbohydrates have facilitated understanding of the roles of glycoproteins and carbohydrates in many cellular and signaling processes, paving the way for the exploitation of carbohydrates in disease diagnosis and drug discovery. Here, we introduce the most recently developed analytical methods, which have been routinely used in many research laboratories. Following the protein separation by one-dimensional (1D) and two-dimensional (2D) polyacrylamide gel electrophoresis (PAGE), gel-based staining methods provide the initial step to identify candidate glycoproteins so that further characterization can proceed. Combined liquid chromatography and mass spectrometry provide an invaluable technology for quantitative analysis of glycoproteins including glycopeptides and glycans and to identify the glycosylation site. The advanced technology of the carbohydrate-based microarray system incorporates high-throughput analysis to extend the scope of biomedical research on carbohydrate-mediated molecular interactions.