PURIFICATION AND CHARACTERIZATION OF GOAT MILK OLIGOSACCHARIDES BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY AND HIGH FIELD PROTON NUCLEAR MAGNETIC SPECTROSCOPY

Abstract

Five novel neutral oligosaccharides have been purified from goat milk using Bio-Gel P-4 and reverse phase C-18 high performance liquid chromatography. Their structures, as determined by high field H-NMR, are : T-V GlcNAc (8 1,6) Gal (6 1,4) Glc P-II Gal (3 1,4) GlcNAc (3 1,6) Gal ( 3 1,4) Glc P-I Gal ( 6 1,3) ^GlcNAc (3 1,3) Gal (3 1,4) Glc Gal (3 1,4) ^ P-III Gal (3 1,4) GlcNAc (3 1,6) Gal (3 1,4) Glc t Fuc (a 1,3) P-IV Gal (3 1,3) GlcNAc (3 1,6) Gal (3 1,4) Glc t Fuc (a 1,3) Structurally, the goat milk oligosaccharides differ markedly from that of the corresponding oligosaccharides from human milk [Dua, V.K. and Bush, C.A. (1983) Anal. Biochem. 133, 1-8]. The oligosaccharide P-I has an interesting structure in the sense that it has two galactose residues linked via 3 1+3 and 31 + 4 linkage, respectively, to the same GlcNAc residue at the non-reducing end. The biological functions of these oligosacc harides are unknown. However, they can serve as substrates for various glycosyltransferases involved in the synthesis of complex carbohydrates of milk. They would also be useful in characterization of related structures from glycolipids and glycoproteins.