SDS-PAGE is a core analytical technique used to separate proteins according to their molecular weight. Before loading, proteins are treated with sodium dodecyl sulfate (SDS), a detergent that unfolds them into linear chains and gives each molecule a uniform negative charge. This removes differences caused by native structure or intrinsic charge. When an electric field is applied, the proteins migrate through the polyacrylamide gel matrix. The gel acts like a molecular sieve. Smaller proteins pas