SIMULTANEOUS SEPARATION OF THE BETA-LACTOGLOBULIN-A, BETA-LACTOGLOBULIN-B AND BETA-LACTOGLOBULIN-C VARIANTS USING POLYACRYLAMIDE-GEL ELECTROPHORESIS

A method for the simultaneous separation of the A, B and C variants of beta-Lg was developed using polyacrylamide slab gel electrophoresis. A resolving gel of 6% acrylamide (2.6% Bis acrylamide) at pH 8.5 in a sodium berate buffer system was used. The inclusion of a stacking gel of 4% acrylamide (2.6% Bis) at pH 6.8, although not essential improved the separation. Because the casein proteins migrated in the same posi tion as the beta-Lg C variant, it was necessary to remove casein from milk samples by acid precipitation and centrifugation. Running conditi ons involved high voltages (210 V) for short periods in order to focus the proteins into a sharp band and to migrate the proteins rapidly in to the resolving gel, followed by low voltages to achieve separation o f the beta-Lg variants.