Structure identification of the complex-type, asparagine-linked sugar chains of beta-D-galactosyl-transferase purified from human milk.
The asparagine-linked sugar chains of human milk galactosyltransferase were quantitatively released as oligosaccharides from the polypeptide backbone by hydrazinolysis. They were converted into radioactive oligosaccharides by sodium borotritiate reduction after N-acetylation, and fractionated by paper electrophoresis and by Bio-Gel P-4 column chromatography after sialidase treatment. Structural studies of each oligosaccharides by sequential exoglycosidase digestion and methylation analysis indicated that the galactosyltransferase contains bi, tri-, and probably tetra-antennary, complex-type oligosaccharides having alpha-D-Manp-(1----3)-[alpha-D-Manp-(1----6)]-beta-D-Manp -(1----4)-beta-D- GlcpNac-(1----4)-alpha-L-[Fucp-(1----6)]-D-GlcNAc as their common core. Variation is produced by the different locations and numbers of the five different outer chains: beta-D-Galp-(1----4)-D-GlcNAc, alpha-L-Fucp-(1----3)-[beta-D-Galp-(1----4)]-D-GlcNAc, alpha-NeuAc-(2----6)-beta-D-Galp-(1----4)-D-GlcNAc, alpha-L-Fucp-(1----3)-[beta-D-Galp-(1----4)]-beta-D-GlcpNAc-(1---- 3)-beta- D-Galp-(1----4)-[alpha-L-Fucp-(1----3)]-D-GlcNAc, and alpha-NeuAc-(2----6)-beta-D-Galp-(1----4)-beta-D-GlcpNAc-(1----3)-beta-D - Galp-(1----4)-[alpha-L-Fucp-(1----3)]-beta-D-GlcNAc.
D001216:Asparagine; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002850:Chromatography, Gel; D004590:Electrophoresis, Paper; D005260:Female; D006023:Glycoproteins; D006801:Humans; D007788:Lactose Synthase / Q000302:isolation & purification; D008745:Methylation; D008895:Milk, Human / Q000201:enzymology*; D009844:Oligosaccharides / Q000032:analysis; D011247:Pregnancy
D006023:Glycoproteins; D009844:Oligosaccharides; D001216:Asparagine; D007788:Lactose Synthase