Applicability and limitations of affinity capillary electrophoresis and vacancy affinity capillary electrophoresis methods for determination of complexation constants

Abstract

ACE and vacancy affinity capillary electrophoresis (VACE) are the commonly used methods for determination of complexation constants by CE. The applicability and limitations of these methods were tested experimentally and by means of simulations using our simulation software Simul 5 Complex. It was shown that while the ACE method provides reliable and precise values of complexation parameters, those determined by VACE can be incorrect especially in the case of strong complexation. The effective mobilities of the system peaks in the VACE method, and consequently, the resulting complexation parameters were found to be a function of concentration of the analyte present in the BGE. Development of system peaks in VACE is discussed in the frame of the linear theory of electromigration. Dependence of mobility of system peaks on the composition of the BGE cannot be characterized by a simple analytical expression as in the case of ACE method. Thus, the VACE method fails and the resulting complexation constants might seriously differ from the reality.

In‐depth insight into the methods of plasma protein‐drug interaction studies: Comparison of capillary electrophoresis‐frontal analysis, isothermal titration calorimetry, circular dichroism and equilibrium dialysis

“…Many CE‐based experimental approaches have been developed for the study of biomolecular interactions, utilizing the changes in the mobility of the interaction partners after their association or estimation of the amounts of free and bound partners . They are characterized by several important benefits such as no need for highly purified samples, immobilization, and labelling of any of the interacting partners.…”

Recent developments in capillary and microchip electroseparations of peptides (2011–2013)

“…All these methods utilize the differences in the migration velocities of the interacting species. Both theoretical and experimental considerations for these methods and their applications for estimation of binding constants have been outlined in the above reviews ; particular recent applications to peptide interaction studies are presented in Section .…”

“…ACE is now widely used for determination of association or dissociation constants of biomolecular complexes with different types of both low and high molecular mass ligands including peptides, for a review see . Interaction of β‐naphthylamide derivatives of five dipeptides and two AAs with hyaluronic acid and HSA at 25°C in acetate buffer (pH 4.65) and phosphate buffer (pH 7.40) were investigated by frontal analysis mode of ACE .…”

Thermodynamic parameters for the complexation of water‐insoluble betulin derivatives with (2‐hydroxypropyl)‐γ‐cyclodextrin determined by phase‐solubility technique combined with capillary zone electrophoresis

“…CE has advantages such as rapidity, high selectivity, small value of samples, and low operating costs. The most used approach is mobility shift ACE . In this method, binding constants are determined based on the change in electrophoretic mobilities of the studied compounds with varying the ligand content in BGE.…”