Electrophoretic recovery of proteins from polyacrylamide gel

Abstract

Polyacrylamide gel electrophoresis, which can effectively resolve a mixture of proteins into individual constituents with a simple apparatus, has been widely and routinely used for analytical purposes. However, its application for preparative purposes is limited owing to the lack of a universal method that permits the recovery of general proteins from the gel in high yields. In early days, the electrophoretically separated protein in gel was recovered by extraction or solubilization of the excised gel, and later by electrophoretic elution. Regarding the electrophoretic recovery of proteins, a number of methods have been reported, which can be divided into two categories: (1) “electroelution”, which recovers the protein of interest from excised gel electrophoretically, and (2) “continuous elution” of applie proteins from a preparative-scale gel during electrophoresis, where the electrophoretically separated proteins that migrate through the gel into a buffer stream at the gel bottom are fractionated consecutively. Characteristic features of the electroelution method reside in its simple requirements for the elution apparatus and that microgram amounts of protein can be quantitatively recovered in the concentrated form. The major drawbacks of electroelution are that the method requires manipulations for locating the protein in the gel, followed by the excision and re-electrophoresis of the relevant part of gel for eluting the protein. The continuous elution method, on the other hand, has advantages in its high loading capacity of sample protein and easy monitoring of the elution process. This method, however, requires expensive equipment and gives low concentrations of the recovered protein, the purity of which is sometimes poor. For those who are trying the electrophoretic recovery of protein from polyacrylamide gel for the first time, the electroelution method would be the first choice in view of the easy manipulation, the small amount of protein required for loading and the satisfactory recovery yield with least expense without using of any costly equipment.