Affinity Capillary Electrophoresis as a Tool to Characterize Intermolecular Interactions

Abstract

Abstract The application of affinity capillary electrophoresis (ACE), a submode of capillary zone electrophoresis, to investigate the interactions between ligands and their substrates is described in this chapter. Using ACE, it is possible to characterize noncovalent molecular interactions (complexation and partition equilibria) of different binding strengths. Resulting association constants ( K ) provide a measured value of the affinity of a ligand molecule to a substrate. Starting with the background of high‐performance capillary electrophoresis (HPCE), in general, and ACE, various possibilities are given how ACE can be used in capillaries or chips. A brief mathematical description of the context between measured parameters (ionic mobility, peak area, or peak height) and evaluated binding parameters (as binding constants and stoichiometry number), as well as various ACE modes and constellations of intermolecular interacting molecules suitable for a wide range of applications are provided. Finally, selected applications are described in detail in terms of the experimental setup and estimation of the binding strength by a suitable mathematical model.