Isolation of β-Lactogobulin and α-Lactalbumin by Gel Filtration Using Sephacryl S-200 and Purification by Diethylaminoethyl Ion-Exchange Chromatography

a-Lactalbumin (a-LA) and I3-lactoglobulin (I3-LG) are the major albumins of bovine milk acid whey. Both proteins have been isolated and crystallized by a number of methods For example, the procedure used by Aschaffenburg and Drewry (3) to isolate a-LA and I3-LG from sodium sulfate whey of cows whole milk utilized high concentrations of ABSTRACT f3-Lactoglobulin dimer (408 mg) was easily and gently separated from neutralized acid whey (200 ml) by gel filtration as the fourth peak eluted from Sephacryl S-200. This I3-lactoglobulin was separated into A (63%) and B (37%) variants by DEAE ion-exchange chromatography at pH 6.8. f}-Lactoglobulin A and B variants each showed single bands of similar mobility on SOO-PAGE and double bands with like mobilities on SDS-urea-PAGE; however, the variants showed different mobilities on native PAGE. a-Lactalbumin (98 mg) was also easily and gently separated by the gel filtration as the fifth peak (134 mg protein). Other proteins recovered in P5 fraction were trace amounts of I3-lactoglobulin monomer and an unidentified albumin (14,000 Da). After purification by Aschaffenburg and Drewry's method, f3-lactoglobulin monomer was absent from alactalbumin fraction; however, the unidentified albumin remained.