Studies on the Proteins of Human Milk

Part VIII. Isolation and Characterization of Human Milk β² A-Globulin

Abstract

1. Two fractions containing milk β₂A-globulin were prepared from human milk, and milk β₂A-globulin was isolated by re-chromatography of the fractions on DEAE-cellulose column.
2. Chemical composition of the final preparation of milk β₂A-globulin was as follows: nitrogen 11.01%, phosphorus 0.13%, hexose (galactose+mannose) 3.43%, hexosamine (glucosamine) 3.74%, fucose 2.72% and sialic acid 3.22%.
3. The final preparation of milk β2A-globulin was pure immunoelectrophoretically and electrophoretically with an electrophoretic mobility of -2.8×10^-5 cm² volt^-1 sec^-1 in a veronal buffer (pH 8.5, ionic strength 0.1) at 0.1 and an isoelectric point at pH 5.8.
4. By sedimentation experiments, it appeared to be homogeneous in a phosphate buffer (pH 7.0, ionine strength 0.1). The sedimentation coefficient extraporated to zero concentration was 5.14S.