Preparative separation and characterization of beta-lactoglobulin genetic variants A and B from bovine milk

We have developed a rapid, preparative polyacrylamide gel elution electroph oresis (PAGE-EL) method for the separation of betalactoglobulin (beta-Lg) v ariants A and B from bovine milk. Six of the 14 electroeluted fractions wer e recognized with polyclonal antisera to beta-Lg A/B. When analyzed by SDS PAGE 4 electroeluted fractions seemed to contain only beta-Lg, while 2 frac tions contained both beta-Lg and alfalactalbumin (alpha-La) according to th eir molecular mass. When the 5 electro eluted fractions that contained only beta-Lg were analyzed by IEF, the isoelectric point (IP) of the protein in 3 electroeluted fractions was the same as the IP of the commercial beta-Lg B, while the IP of the protein in 2 other fractions was the same as that o f commercial bovine beta-Lg A. The results were also confirmed with commerc ial bovine beta-Lg A/B. On this basis we suggest that the protein in the fi rst 2 electroeluted bovine whey fractions is the genetic variant B, and the protein in the other 2 electroeluted fractions is the genetic variant A of bovine beta-Lg. The PAGE-EL-method that we have developed can thus be used for a rapid, preparative scale purification and separation of bovine whey proteins, especially for the separation of the genetic variants A and B of beta-Lg, and the electroeluted bovine whey proteins or their genetic varian ts analyzed further in biologically active form.