Effect of Sodium Dodecyl Sulfate Binding Temperature on Molecular Weights of αs-,β, and κ-Caseins

Abstract

Molecular weights of αs-, β-, and κ-caseins were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Sodium dodecyl sulfate was bound to these casein components at room temperature or by incubating at 40C overnight or at 80C for 1h. Binding of sodium dodecyl sulfate to αs-casein in absence of heat gave a molecular weight of 30,400 which was 3000 to 4000 daltons less than that for αs-casein bound at 40 and 80C. The molecular weight of β-casein bound at 40 and 80C was 6000 to 7000 daltons higher than that bound to sodium dodecyl sulfate at room temperature. Although the molecular weight of κ-casein did not vary substantially under the three treatments, break-down products ensued from it, especially at 80C. Sodium dodecyl sulfate binding to casein components should be at room temperature.