Gradient SDS Polyacrylamide Gel Electrophoresis of Proteins

Abstract

The preparation of fixed-concentration polyacrylamide gels has been described in Chapters 20 and 21. However, the use of polyacrylamide gels that have a gradient of increasing acrylamide concentration (and hence decreasing pore size) can sometimes have advantages over fixed-concentration acrylamide gels. During electrophoresis in gradient gels, proteins migrate until the decreasing pore size impedes further progress. Once the “pore limit” is reached, the protein banding pattern does not change appreciably with time, although migration does not cease completely (1). There are two main advantages of gradient gels over linear gels.