What is the purpose of SDS-PAGE?

The purpose of SDS-PAGE is to separate proteins by molecular weight while in a denatured state. This technique utilizes sodium dodecyl sulfate (SDS), an anionic detergent that denatures proteins by unfolding them and imparting a negative charge proportional to their length. When an electric current is applied during electrophoresis, the denatured proteins migrate through a polyacrylamide gel matrix. Smaller proteins move through the gel matrix more easily and therefore travel further than larger ones. This allows for the separation of proteins based on their molecular weight, enabling researchers to analyze protein size, purity, and to identify proteins in complex mixtures such as cell lysates.