Application of Electrophoresis on Paper to the Estimation of Alpha-, Beta-, and Gamma-Casein

Abstract

Alpha-, beta-, and gamma- components of the casein complex were separated by electrophoresis on filter paper. Estimation of the separated protein fractions was accomplished by direct photometry of the dyed protein in filter paper. Dye-binding capacities of alpha-, beta-, and gamma-casein prepared by a chemical method, were measured experimentally. With the staining procedure used, the components did not bind the dye in proportion to the amount of protein present. Correction factors based on the differences in dye-binding capacities of the protein fractions were determined. The photometric results, corrected for deviation from Beer''s Law and for differences in dye-binding capacities agreed with results obtained by protein nitrogen analyses. The percentage composition of casein components analyzed in this manner was of the following order: alpha- 60%; beta- 32%; gamma- 9%.