Protein purification by counteracting chromatographic electrophoresis--on the disparity of focusing conditions.

The inconsistency in the focusing data on ferritin by the technique of Counteracting Chromatographic Electrophoresis, reported as flow rate vs potential gradient has been examined. Voltages in the gel region have been measured and analyzed, which are indicative of the fact that the potential gradients in the including and excluding gel regions vary from each other; those gradients are also different from the potential gradients in the buffer and polyacrylamide plug regions. Hence the existence of a constant voltage gradient (across the entire column) implied in the literature so far is not quite correct. The ionic strength of the carrier buffer, the chemical nature of the buffer components and the temperature of experimentation tend to obscure the 'true' data on stable accumulation zone formation.