HIGH-PERFORMANCE ELECTROPHORESIS CHROMATOGRAPHY OF BOVINE-MILK COMPONENT-3 GLYCOPROTEINS

Component 3 corresponds to the hydrophobic fraction of bovine milk proteose-peptone and is composed of three principal glycoproteins with molecular masses of 11, 19, and 29 KDa. To understand better its interesting emulsifying properties and its capability of inhibiting spontaneous lipolysis in milk, isolation and characterization of the three glycoproteins are needed. The newly introduced technique of high performance electrophoresis chromatography is an efficient tool to prepare these glycoproteins in high purity. This preparative technique offers the resolving power of gel electrophoresis with the automatization associated with HPLC. Parameters that influence protein separation are discussed. The isolated 19- and 29-kDa glycoproteins, which bind to immobilized concanavalin A, are then characterized by analysis of their glycan and amino acid compositions. In particular, the glycan molar ratio of the 19-kDa glycoprotein is in good agreement with a biantennary N-acetyllactosamine-type glycan structure.