Carbohydrates of the Milk of the Platypus

Abstract

Twelve samples of milk of the platypus, Ornithorhynchus anatinus, had a mean content of 3· 3 % hexose. Of this, almost half was L-fucose. Of the total monosaccharides present in acid hydrolysates of the water-soluble carbohydrates, L-fucose constituted 33 %, D-galactose 29 %, glucosamine 20 %, D-glucose 11 % and sialic acid 7 %. Free lactose was found in only trace amounts. In all samples, the major oligosaccharide was difucosyliactose, which represented 39-52 % of the total hexose. Five higher neutral oligosaccharides (from penta- to nonasaccharides) were isolated and their monosaccharide compositions determined. Each contained one or more residues of fucose, glucosamine and galactose and one residue of glucose. The presence in the milk of 4-0-acetyl-Nacetylneuraminlactose was detected by thin-layer chromatography. All milk samples examined contained protein material (probably glycoprotein), which was not precipitated by chloroformmethanol extraction. No evidence was obtained for quantitative or qualitative changes in carbohydrates during the course of the lactation season except for a small decline in total hexose towards the end of the season.