Protein purification by counteracting chromatographic electrophoresis: quantitative focusing limits and protein selection at the interface.

Counteracting chromatographic electrophoresis combines the principles of gel permeation chromatography and gel electrophoresis to select and enrich the target protein at the interface between two gels of different internal porosity. The gel combination, carrier buffer pH, voltage gradients in the gel regions, buffer flow velocity, the size of the protein and its electrophoretic mobility influence the selection of experimental conditions for optimal separation. Purification factors of the order of 100-1000 are obtained in a single step in a column of about 10-20 cm length. This method can be extended to nucleic acids and other charged macromolecules.