Gel Electrofocusing

Abstract

Gel electrofocusing provides rapid analytical fractionation of amphoteric compounds, such as proteins, on the basis of their isoelectric points. The high resolving power of density gradient electrofocusing is combined with the convenience and flexibility of gel electrophoresis. Gel electrofocusing is an extension of the technique of electrofocusing in a density gradient and is based on the same principle of fractionation. Replacement of the density gradient by a gel as separation support makes the procedure more suitable for analytical fractionation of many small samples. A stable pH gradient is produced by applying a voltage to a mixture of carrier ampholytes in a column or slab of gel. The carrier ampholytes become arranged in the gel in order of increasing isoelectric point from anode to cathode. They are confined to the gel by using dilute solutions of a strong acid and a strong base in anode and cathode compartments, respectively. Molecules of a protein migrate in the pH gradient until they become concentrated in the pH region, where the protein is isoelectric. © 1971, Elsevier Inc. All rights reserved.