Glycoproteins from mature human milk whey

Two milk-specific glycoprotein fractions and serum orosomucoid were isolated from mature human milk. One of the milk-specific glycoproteins was homogeneous and was termed glycoprotein A. Its sedimentation and diffusion constants were 2.6 S and 6.3 F, respectively, giving a molecular weight of 29,5000. It contained some 70% carbohydrate consisting of sialic acid, galactose, fucose, glucosamine, and galactosamine. It was not immunologically related to serum orosomucoid. The other glycoprotein, called glycoprotein B, was heterogeneous with an average molecular weight of near 4,000, and carbohydrate comprised some 75% of its weight. Both glycoprotein fractions supported the growth of Lactobacillus bifidus var. Penn. Removal of sialic acid enhanced the growth-promoting activity of glycoprotein B but not of A.