Protein Extraction from Gels: A Brief Review

Protein gel electrophoresis is an important procedure carried out in protein studies. Elution and recovery of proteins separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) are often necessary for further downstream analyses. The process involves localizing the protein of interest on the gel following SDS-PAGE, eluting the protein from the gel, removing SDS from the eluted sample, and finally renaturing the protein (e.g., enzymes) for subsequent analyses. Investigators have extracted proteins from gels by a variety of techniques. These include dissolution of the gel matrix, passive diffusion, and electrophoretic elution. Proteins eluted from gels have been used successfully in a variety of downstream applications, including protein chemistry, proteolytic cleavage, determination of amino acid composition, polypeptide identification by trypsin digestion and matrix-assisted laser desorption ionization-time of flight mass spectroscopy, as antigens for antibody production, identifying a polypeptide corresponding to an enzyme activity, and other purposes. Protein yields ranging from nanogram levels to 100 μg have been obtained. Here, we review some of the methods that have been used to elute proteins from gels.