DEVELOPMENT OF ELECTROPHORETIC CONDITIONS FOR THE CHARACTERIZATION OFPROTEIN GLYCOFORMS BY CAPILLARY ELECTROPHORESIS ELECTROSPRAY MASS-SPECTROMETRY

A capillary electrophoresis (CE) method using acidic buffers and capil laries coated with Polybrene, a cationic polymer has been developed fo r the separation of glycoproteins and glycopeptides. Electrophoretic c onditions have been optimized to provide resolution of individual glyc oforms observed for different glycoprotein preparations. These conditi ons were found to be entirely compatible with the operation of electro spray mass spectrometry (ESMS), which facilitated the assignments of p ossible carbohydrate compositions of glycopeptides arising from digest s of glycoproteins. By using operating conditions enhancing the format ion of oxonium fragment ions prior to mass spectral analysis, selectiv e identification of glycopeptides was achieved for complex samples suc h as those from proteolytic digests or chemical cleavages. Examples of applications are presented for ribonuclease B, ovalbumin, horseradish peroxidase, and a lectin from Erithrina corallodendron using both CE- ESMS and CE with ultraviolet detection (CE-UV).