Fractionation and Characterization of Milk Proteins by Column Chromatography and Electrophoresis

Abstract

Milk-protein fractionation methods were studied with anion exchange chromatography, paper, and gel electrophoresis and optimal separation conditions were established. The best results were obtained when chromatographic separations were on DEAE-cellulose column (35 × 2.5 cm) with either 5 to 6 ml of skimmilk or 20 ml of whey applied and gradient eluted; paper electrophoretic analyses of either 60 µliters skimmilk or 120 µliters whey on Whatman 3 mm paper strips were performed at pH 6.8 in .067 M collidine acetate buffer and at a potential of 10.6 v/cm for 16 hours at 4 C; and polyacrylamide gel electrophoretic analyses of .3 mg protein per tube were performed at pH 8.3 and at 3.75 mamp per tube of 7.0 × .5 cm for 50 minutes at 21 to 25 C. Skimmilk protein fractions were identified with casein and whey protein markers. Attention is drawn to the effects of cold preservation of the samples at 4 C, −17 C and −78 C, and of freeze-drying on the milk protein patterns. © 1972, American Dairy Science Association. All rights reserved.