Capillary Electrophoresis of PEGylated Proteins

摘要

Capillary electrophoresis has become a well-established technique for evaluating the composition and concentrations of a wide range of protein samples. In addition, capillary electrophoresis can be used to study a variety of protein properties including the net protein charge5, the extent of ion binding, and the presence of specific biomolecular interactions. This wide range of applications is possible, at least in part, because of the strong theoretical foundation for describing the electrophoretic mobility of globular proteins. Smoluchowski's initial analysis of the electrophoretic mobility is valid for arbitrary particle shape under conditions where the Debye length (double layer thickness) is much smaller than the characteristic particle size. Subsequent studies have accounted for the finite size and relaxation of the electrical double layer, the effects of non-spherical particle geometry, and the influence of particle porosity. The resulting theoretical expressions for the electrophoretic mobility are in good agreement with experimental results. In contrast, much less is known about the electrophoretic mobility of more complex biomolecules. For example, there is considerable interest in the use of PEGylated therapeutic proteins, formed by the covalent attachment of one or more polyethylene glycol chains to the native protein. PEGylation can significantly increase the biological half-life by reducing the rate of kidney clearance, and it can also minimize adverse immunological reactions, dramatically improving the overall efficacy of the therapeutic protein.