Structural Studies of a Hexasaccharide from a Blood‐Group‐Active Glycoprotein and Evidence for the Binding of Its Terminal Non‐Reducing N‐Acetyl‐d‐glucosamine Residues to Wheat Germ Agglutinin

Abstract

We have isolated blood-group substance H from pig stomach mucosa and subjected the glycoprotein to two consecutive cycles of Smith degradation. The wheat germ agglutinin hemagglutination was strongly inhibited by the native glycoprotein and its first Smith degradation product. A second cycle of Smith degradation resulted in the loss of most of the inhibitory activity. Methylation analyses of undegraded and Smith-degraded glycoprotein demonstrated a strong correlation between the number of terminal N-acetylglucosamine residues and the wheat germ agglutinin reactivity.An oligosaccharide (Hf) which inhibited the wheat germ agglutinin hemagglutination more strongly than N,N',N"-triacetylchitotriose was isolated from the mixture of degradation products obtained upon alkaline sodium borohydride treatment of blood-group substance H. We hfve previously shown that oligosaccharide Hf contains galactose, N-acetylglucosamine and N-acetylgalactosaminitol in a molar ratio of 2: 3 : 1 and has inhibitory activity sensitive to N-acetylglucosaminidase of Trichomonasfoetus [Tuppy, H. and Wrann, M., Monatsh. Chem. 109 (1978) 703 -7101.The methylation analyses described in this paper indicate that: firstly, oligosaccharide Hf is a branched hexasaccharide, 3,6-linked N-acetylgalactosaminitol being the branching point. The mass spectrum of 1,4,5-tri-O-methyl-3,6-di-O-acetyl-2-deoxy-2-(N-methylacetamido)-galactitol is shown. Secondly, both nonreducing termini of oligosaccharide Hf are occupied by N-acetylglucosamine, the third N-acetylglucosamine residue is 4-linked. One of the galactose residues is substituted in position 4, the other in position 2. Thirdly, the loss of inhibitory activity of oligosaccharide Hf after treatment with N-acetylglucosaminidase of Trichomonas foetus is a result of the removal of a terminal N-acetylglucosamine residue from the 2-position of the respective subterminal galactose residue.The structure of oligosaccharide Hf and the significance of terminal N-acetylglucosamine residues for the wheat germ agglutinin inhibition are discussed.

Mucin biosynthesis. Properties of a bovine tracheal mucin β-6-N-acetylglucosaminyltransferase

“…The ion-fragment pattern agreed with that of 1,5-diacetyl-2,3,4,6tetramethylgalactitol (Bjorndahl et al, 1967). Peak 2 had primary m/z ion fragments of 45,117,159,161, 203 and 205, and thus was derived from unsubstituted N-acetylglucosamine (Wrann & Tappy, 1978). Peak 3 gave primary m/z ion fragments of 45, 117, 130, 161, 246 and 318.…”

Receptors for the Lectins Wheat Germ

“…The monosaccharide specificity of SBA and RCA I, respectively, is identical with that of blood group antigen A and that of blood group antigen B. However, precursor blood group substances have also been shown to react with WGA and SBA (19,27).…”