Molecular weight estimation of polypeptides by SDS-polyacrylamide gel electrophoresis: Further data concerning resolving power and general considerations

Abstract Molecular weights of polypeptides and proteins can be determined with a high degree of accuracy by electrophoresis in SDS-polyacrylamide gels. Coelectrophoresis of dual-labeled markers and unknowns permits resolution of molecular weight differences as small as 5% (and possibly 2%) between polypeptides. Experiments with S35-labeled SDS suggest that the SDS-protein complex is a loose one and that exchange of SDS with the environment occurs at an exceedingly high rate.