Comparative Analysis of the Molecular Heterogeneity of Ceruloplasmin from Human Blood and Breast Milk

L. V. Puchkova,^1,2 E. T. Zakharova,¹ T. D. Aleinikova,¹ S. V. Mokshina,^1,3 N. V. Tsymbalenko,¹ L. K. Sasina,¹ M. R. Shirmanova,^1,3 N. P. Rogacheva,³ and V. S. Gaitskhoki¹

¹Research Institute of Experimental Medicine, Russian Academy of Medical Sciences, ul. Akademika Pavlova 12, St. Petersburg, 197376 Russia; fax: (8-812) 234-9489; E-mail: ludmila@usr8.iem.ras.spb.ru

²To whom correspondence should be addressed.

³North-Western Polytechnical Institute, ul. Millionnaya 8, St. Petersburg, 196035 Russia.

Submitted April 9, 1997.

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The content of ceruloplasmin (Cp) was determined in 96 samples of human breast milk using rocket immunoelectrophoresis and measurement of Cp oxidase activity. The concentration of immunoreactive Cp in milk decreased about 9 times during the first 20 days of lactation while the specific oxidase activity decreased only 4 times. Two-dimensional electrophoresis of purified milk Cp before and after its treatment with chelating agents showed that copper atoms in milk Cp are more sensitive to EDTA treatment that those in blood Cp. The comparison of the different lectin-binding ability of blood and milk Cp's revealed a difference in the composition of their carbohydrate chains. The mechanisms controlling the uptake of copper ions by newborns at the level of the expression of the Cp-encoding gene in the mammary gland of the mother are discussed.

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KEY WORDS: milk ceruloplasmin, mammary gland, copper uptake.

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