[A new method for human milk protein separation].

Attempts at isolating individual human milk proteins showed that cross interactions made it difficult to obtain of homogeneous components. A new method was devised, based on complete precipitation of milk proteins with saturated ammonium sulphate and progressive solubilization of the precipitate on a column of Sephadex G10 with a linear gradient of ammonium sulphate (from saturation to water). Three fractions were obtained. The first contained lactoferrin, serum albumin, lysozyme and traces of alpha-lactalbumin. Lysozyme could be obtained free from contaminants by chromatography on Ultrogel AcA 54. Lactoferrin and serum albumin coeluting as a single peak, were separated by a further chromatography on DEAE-cellulose. From the other two fractions recovered on Sephadex G10, it should be possible to prepare immunoglobulins, alpha-lactalbumin and the bulk of caseins. The homogeneity of the preparations of lysozyme, lactoferrin and serum albumin was assessed by SDS polyacrylamide gel electrophoresis, acrylamide agarose electrophoresis and immunoelectrophoresis.