Methods for the estimation of binding constants by capillary electrophoresis

Abstract

Capillary electrophoresis (CE) has developed into a particularly effective means to determine apparent equilibrium constants for molecular association in solution (e.g., to micelles, cyclodextrins, antibiotics, proteins, RNA, DNA, etc.). The various experimental, graphical and mathematical approaches for determining association constants are reviewed. In CE, association constants can be calculated because there is a relationship between substrate concentration and the measured electrophoretic mobility of the solute. Most of the approaches for obtaining association constants by CE are conceptually and mathematically related to one another. Likewise, they are analogous to many spectroscopic techniques that are used for obtaining association constants. The advantages, limitations and proper use of the various CE approaches are examined.

Application of Retention Factors in Affinity Electrokinetic Chromatography and Capillary Electrophoresis

“…(4), changes in the viscosity of the background electrolyte and possible complexation with surfactant monomers due to addition of the pseudo-stationary phase have to be considered and corrected for. 17,[28][29][30][31] Usually the analyte and marker molecule concentrations used in EKC are kept low in order to comply with the assumption that the mobility of the pseudo-stationary phase is not affected by interaction with these molecules. The presence of a solute in the pseudo-stationary phase, however, may affect the structural properties of the phase, and thus both the solute distribution and electrophoretic migration.…”

“…32 More elaborate discussions on the prerequisites of mobility shift affinity CE and EKC can be found elsewhere. 3,6,8,[29][30][31]33 Having established the equations appropriate for affinity EKC studies as well as the fundamental practical concerns in brief, it may be timely to ask when it is advantageous to apply EKC instead of the ACE approach. Neubert et al referred to the two closely related approaches, as the partition (distribution) and the association model, respectively.…”

Recent advances in the study of biomolecular interactions by capillary electrophoresis

“…Besides, Joule heat, high electric field, wall effect, and properties of the running buffer may also influence the migration of analytes to some extent [18]. In studies of molecular interactions, different CE modes, equipments, or even differences in ligand or receptor concentrations may cause quantitative discrepancies [19][20][21].…”

Separation of drug enantiomers by capillary electrophoresis in the presence of neutral cyclodextrins

“…allow one to judge the influence of the permethylation on the migration separation factors (a ) and on Mann, Medice, E. Merck, 3M Medica, Pfizer, Pharwith the cyclodextrin host. The determination of K macia, Rhone-Poulenc Rorer, Robugen, Roche, by CE has been reported elsewhere [25,26]. Rohm Pharma, Schering, Sigma, Thiemann, WelSimilar to the effective mobility difference of the lcopharm, and Zyma.…”

“…A detailed presentation It should be noted that changes in the viscosity of the of the fraction of successful enantiomer separations buffer upon CSA addition may cause a small, yet (''success rate R '') for analytes of the two strucsuc undetermined uncertainty to a comparison of two ture classes is given in Fig. 3 CSAs is hindered by the low solubility of b-CD in the electrophoretic data [26], we choose to divide the the running buffer. total of 86 chiral drugs into two classes, according to Likewise, analytes containing the substructure 4H their chemical structure, one class where the subhave a higher affinity, as judged from the fraction of structure 4H [16] (see Fig.…”