COMPARATIVE-ANALYSIS OF THE MOLECULAR HETEROGENEITY OF CERULOPLASMIN FROM HUMAN BLOOD AND BREAST-MILK

The content of ceruloplasmin (Cp) was determined in 96 samples of huma n breast milk using rocket immunoelectrophoresis and measurement of Cp oxidase activity. The concentration of immunoreactive Cp in milk decr eased about 9 times during the first 20 days of lactation while the sp ecific oxidase activity decreased only 4 times. Two-dimensional electr ophoresis of purified milk Cp before and after its treatment with chel ating agents showed that copper atoms in milk Cp are more sensitive to EDTA treatment that those in blood Cp. The comparison of the differen t lectin-binding ability of blood and milk Cp's revealed a difference in the composition of their carbohydrate chains. The mechanisms contro lling the uptake of copper ions by newborns at the level of the expres sion of the Cp-encoding gene in the mammary gland of the mother are di scussed.