Rapid Separation and Quantification of Major Caseins and Whey Proteins of Bovine Milk by Polyacrylamide Gel Electrophoresis

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      A rapid polyacrylamide gel electrophoretic method was developed for separating and quantifying major proteins in casein and whey protein fractions of bovine milk. For casein separation, best results were achieved by an 8% polyacrylamide gel containing 4 M urea and a top layer of large pore sample gel; for whey protein the most satisfactory separation was with 12% polyacrylamide gel in the absence of urea and a large pore gel. Electrophoretic conditions for separation of whey protein were also applicable for identifying genetic variants of β-lactoglobulin. Densitometric tracings were used to resolve and quantify protein peaks from stained bands in the gels. Casein was resolved into three major fractions with relative proportions of 50:30:15 for αs1- and αs2-casein, β-casein, and κ-casein. Whey protein was resolved into four major fractions with relative proportions of approximately 60:20:7:13 for β-lactoglobulin, α-lactalbumin, serum albumin, and immunoglobulin.


        • Anderson M.
        • Andrews A.T.
        Progressive changes in individual milk protein concentrations associated with high somatic cell counts.
        J. Dairy Res. 1977; 44: 223
        • Barry J.G.
        • Donnelly W.J.
        Casein compositional studies. II. The effect of secretory disturbance on casein composition in freshly drawn and aged bovine milks.
        J. Dairy Res. 1981; 48: 437
        • Bell J.W.
        • Stone W.K.
        Rapid separation of whey proteins by cellulose acetate electrophoresis.
        J. Dairy Sci. 1979; 62: 502
        • Darling D.F.
        • Butcher D.W.
        Quantification of polyacrylamide gel electrophoresis for analysis of whey proteins.
        J. Dairy Sci. 1976; 59: 863
        • Davis B.J.
        Disc electrophoresis II. Method and application to human serum proteins.
        Ann. New York Acad. Sci. 1962; 121: 404
        • El-Negoumy A.M.
        Two rapid and improved techniques for chromatographic fractionation of casein.
        J. Dairy Sci. 1976; 59: 153
        • Feagan J.T.
        • Bailey L.F.
        • Hehir A.F.
        • McLean D.M.
        • Ellis N.J.S.
        Coagulation of milk proteins. II. Effect of genetic variants of milk protein on rennet coagulation and heat stability of normal milk.
        Aust. J. Dairy Technol. 1972; 27: 129
        • Feagan J.T.
        • Griffin A.T.
        • Lloyd G.T.
        Effects of subclinical mastitis on heat stability of fluid milk.
        J. Dairy Sci. 1966; 49: 933
        • Haenlein G.F.W.
        • Schultz L.H.
        • Zikakis J.P.
        Composition of proteins in milk with varying leucocyte counts.
        J. Dairy Sci. 1973; 56: 1017
        • Jenness R.
        The composition of milk.
        in: Lactation. Vol. 3. Academic Press, New York, NY1974: 3-107
        • McKenzie H.A.
        Methods for zone electrophoresis of milk proteins.
        in: Milk proteins. Chemistry and molecular biology. Vol. 2. Academic Press, New York, NY1971: 483-507
        • Morr C.V.
        • Josephson R.V.
        • Jenness R.
        • Manning P.B.
        Composition and properties of submicellar casein complexes in colloidal phosphate-free skim milk.
        J. Dairy Sci. 1971; 54: 1555
        • Ng Kwai Hang K.F.
        • Hayes J.F.
        Effects of potassium dichromate and sample storage time on fat and protein by Milko-Scan and on protein and casein by a modified Pro-Milk Mkll method.
        J. Dairy Sci. 1982; 65: 1895
        • Swaisgood H.
        Methods of gel electrophoresis in milk proteins.
        Publ. Am. Dairy Sci. Assoc., Champaign, IL1975
        • Tarassuk N.P.
        • Yaguchi M.
        • Callis J.B.
        Effect of temperature on composition of casein fractions eluted from diethylaminoethyl cellulose column.
        J. Dairy Sci. 1965; 48: 606
        • Whitney R. McL.
        • Brunner J.R.
        • Ebner K.E.
        • Farrell Jr., H.M.
        • Josephson R.V.
        • Morr C.V.
        • Swaisgood H.E.
        Nomenclature of the proteins of cow's milk: Fourth revision.
        J. Dairy Sci. 1976; 59: 795
        • Yaguchi M.
        • Rose D.
        Chromatographic separation of milk proteins: A review.
        J. Dairy Sci. 1971; 54: 1725
        • Yaguchi M.
        • Tarassuk N.P.
        • Hunziker H.G.
        Chromatography of milk proteins on anion exchange cellulose.
        J. Dairy Sci. 1961; 44: 589