Molecular Weight of αs3- and αs4-Caseins by Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis

Molecular weights of both bovine as 3and as4-casein were determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis.Analysis by least squares of natural logarithm of molecular weight versus distance of migration gave a molecular weight of 27,800 + 900 daltons for each protein.The value agrees closely with the molecular weight (26,000 daltons) for bovine as3-casein reported by Richardson and Creamer and is less than 31,800 daltons for reduced ass-casein reported by Toma and Nakai. EXPERIMENTAL PROCEDUREThe minor as-caseins were prepared according to Hoagland et al. (7).Gel electrophoresis