Flow-through partial-filling affinity capillary electrophoresis for the estimation of binding constants of ligands to receptors

Abstract

A new approach for estimating binding constants of ligands to receptors, flow-through partial-filling affinity capillary electrophoresis (FTPFACE), is introduced for studying the interaction of carbonic anhydrase B (CAB, EC 4.2.1.1) with arylsulfonamides and vancomycin fromStreptomyces orientalis with D-Ala-D-Ala peptides. In this technique the capillary is first partially-filled with ligand followed by a sample of receptor and non-interacting standards. Upon application of a voltage the receptor and standards flow into the ligand plug where equilibrium is achieved between the receptor and ligand. Continued electrophoresis results in the receptor and standards flowing through the domain of the ligand plug. Analysis of the change in the relative migration time ratio of the receptor, relative to the non-interacting standards, as a function of the concentration of ligand, yields a value for the binding constant. These values are comparable to those estimated using other binding and ACE techniques. Data demonstrating the quantitative potential of this method is presented.