Separation of cationic proteins via charge reversal in capillary electrophoresis

Analysis of proteins by capillary electrophoresis requires strategies which minimize coulombic interactions with the capillary surface. Thus buffers with pH's above the isoelectric points (pI) of proteins, or near the pI of silanol are required for efficient separation. Covalent modification of the capillary surface is also effective; however, this strategy is technically difficult, abolishes endosmotic flow and suffers from the inherent lability of the siloxane bond. Finally, "dynamic coating" agents, which interact weakly with the capillary surface and therefore, must be included in the separation buffer, suffer from the potential interaction of coating agent with analytes, altering the selectivity of the system. In the following paper, we describe another approach which overcomes all of these difficulties, and demonstrate the ease of use, nondenaturing property, stability and selectivity of the coating strategy with several model protein systems.