Capillary electrophoresis for the study of affinity interactions

Molecular recognition may be characterized both qualitatively and quantitatively by electrophoretic methods if complexed molecules differ in electrophoretic mobility from unbound ones. The use of capillary zone electrophoresis (CE) for the characterization of affinity interactions is advantageous because of the high resolution, reproducibility and wide applicability of the technique and because of the mild conditions, i.e., physiological buffers without additions of organics or detergents, that are often sufficient for highly efficient separations. CE gives the ability to characterize binding between small amounts of unlabelled reactants in solution, has few requirements for special characteristics of the interacting molecules and is also applicable to the study of interactions of individual components in mixtures, as detection of binding and analytical separation are achieved in one step. This is unique compared with other techniques for the study of non-covalent interactions. The advantages and disadvantages of using CE to demonstrate molecular interactions, to screen for specific ligand binding in complex mixtures and to calculate binding constants will be discussed.