The chemical structure of neutral and acidic sugar chains obtained from bovine colostrum κ-casein

Abstract

One neutral oligosaccharide alditol (tetrasacchariditol, 10%) and three acidic oligosaccharide alditols (a tri (28%), tetra (17%) and a pentasacchariditol (44%)) were isolated from, colostrum κ-casein taken 6h after parturition. The neutral tetrasacchariditol and the acidic pentasacchariditol only contained a characteristic N-acetylglucosamine, and the latter was the main carbohydrate portion. The chemical structures were analyzed by methylation analysis with gas-liquid chromatography-mass spectrometry and by anomer analysis with ¹³C nuclear magnetic resonance, and were identified to be galactosyl-β-1-3[galactosyl-β-1-4-N-acetylglucosaminyl-β-1-6-]-N- acetylgalactosaminitol, N-acetylneuraminyl-α-2-3-galactosyl-b-1-3-[galactosyl-β-1-4-N-acetylglucosaminyl-β-1-6-]- N-acetylgalactosaminitol, N-acetylneuraminyl-α-2-3-galactosyl-β-1-3-N-acetylgalactosaminitol and N-acetylneuraminyl- α-2-3-galactosyl-β-1-3-[N-acetylneuraminyl-α-2-6-]-N-acetylgalactosaminitol. The former two were the novel carbohydrate chains of colostrum κ-casein, but the latter two were identical with those which have been found in normal κ-casein.