The molecular weight of a protein can be determined by

the molecular weight of an unknown protein can be determined by using the SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis) method. Although there are some other methods (i.e. analytical ultracentrifugation and light scattering) for calculating the size or molecular weight (MW) of an unknown protein, they are not commonly used for this purpose since they use large amounts of highly purified proteins and require costly equipment.