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Updated: Aug 24, 2026

Identification and Characterization of Protein Glycosylation using Specific Endo- and Exoglycosidases
Published on: December 26, 2011
Purification and characterization of glycolactin, a novel glycoprotein from bovine milk
1Department of Biochemistry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories.
Abstract:
A novel glycoprotein designated glycolactin, with a molecular weight of 64 kDa, a sequence hitherto unknown in the literature and capable of inhibiting the hemagglutinating activities of soybean lectin and Ricinus communis agglutinin 120, was isolated from bovine milk. Its lectin-inhibiting activity differed from that of lactoferrin, another milk protein. Like other milk proteins, glycolactin inhibited superoxide formation in vitro. Glycolactin inhibited cell-free translation in a rabbit reticulocyte lysate system with an IC50 of about 31 nM. It exhibited ribonucleolytic (RNase) activity towards yeast transfer RNA with a pH optimum of 7.5, and specific RNase activity towards poly C. The purification protocol of glycolactin involved removal of globulin from the acid whey fraction of bovine milk by precipitation with 1.8 M (NH4)2SO4, and adsorption on the ion exchangers CM-Sepharose and Mono S. Deglycosylation of glycolactin using glycopeptidase F produced only a slight decrease of 4 kDa in the molecular weight of glycolactin.
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