Biosynthesis of lactosamine in bovine mammary gland

Lactosamine (beta-D-Galp-(1-->4)-D-GlcN) was isolated from bovine milk sampled after intravenous infusion of glucosamine through the jugular vein of a lactating cow. The chemical structure was established by 2D NMR spectroscopy and electrospray ionisation mass spectrometry (ESIMS). Selected ion monitoring liquid chromatography-mass spectrometry (SIMLC-MS) of the perbenzoylated carbohydrate fraction showed the presence of the novel disaccharide in the milk sample after infusion, but not in the control bovine milk sample. The results showed the uptake of glucosamine in bovine mammary gland, and also indicated that a part of glucosamine was metabolised to the product lactosamine.