Measurement of the binding of proteins to polyelectrolytes by frontal analysis continuous capillary electrophoresis.

We have developed a novel technique, frontal analysis continuous capillary electrophoresis (FACCE), to study the binding of proteins to polyelectrolytes. Compared with existing electrophoresis methods such as conventional frontal analysis and the Hummel-Dreyer method, FACCE offers enhanced lower detection limits and is free from effects due to slow binding kinetics, thus making it suitable for studying equilibrium systems. In addition, with a single calibration, FACCE provides for efficient quantitative analysis. Here we report results obtained with β-lactoglobulin as the ligand and sodium poly(styrenesulfonate) (NaPSS) as the ligand-binding substrate. For this model system, FACCE yields reproducible calibration curves and binding isotherms. The binding parameters so determined are compared with previous results for other protein-polyelectrolyte systems.