1] Measurements of molecular weights by gel electrophoresis

Abstract

Publisher Summary This chapter deals with the use of polyacrylamide gel electrophoresis as an analytical tool for the separation and qualitative characterization of charged macromolecules. Restrictions on the use of this procedure for the estimation of molecular weights are emphasized in the chapter, particularly with respect to the now widespread use of polyacrylamide gel electrophoresis in the presence of denaturing detergents. Polyacrylamide gel electrophoresis can be carried out in the absence or presence of denaturating detergent. Polyacrylamide gel electrophoresis in the absence of detergents has become a powerful tool for separating and categorizing protein components in a mixture as long as the following reservations are kept in mind: (1) different proteins can have the same charge/frictional coefficient, and thus the observation of a single band is not a sufficient criterion for purity and (2) relative mobilities are not necessarily an indication of relative molecular weights. Polyacrylamide gel electrophoresis in the presence of denaturing detergents involves a treatment with sodium dodecyl sulfate (SDS). The use of polyacrylamide gel electrophoresis in SDS for molecular weight determinations is based on the fact that the relative electrophoretic mobilities in solution or in polyacrylamide gel electrophoresis are unique function of the molecular weight of a group of polypeptides,.