In SDS-PAGE, proteins migrate towards which electrode?

In SDS-PAGE (Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis), proteins are coated with a negatively charged detergent, SDS, which gives them a uniform negative charge relative to their size. Because of this, when an electric field is applied during electrophoresis, the proteins will migrate towards the positive electrode, also known as the anode.

The migration direction is primarily dictated by the charge of the proteins after treatment with SDS; thus, as they are all uniformly negatively charged, they will move toward the positively charged side of the gel. This property is essential for separating proteins based on their molecular weight, as larger proteins typically move more slowly through the gel matrix compared to smaller ones. The movement towards the anode allows for effective separation and visualization of the proteins following the run.