SYNTHESES OF O-BETA-D-GALACTOPYRANOSYL-(1-]3)-O-(2-ACETAMIDO-2-DEOXY-ALPHA(AND O-BETA-D-GALACTOPYRANOSYL)N-TOSYL-L-SERINE AND THEIR INTERACTION WITH D-GALACTOSE-BINDING LECTINS

In order to use, as hapten inhibitors against various galactose-binding lectins, the derivatives of O-β-d-galactopyranosyl-(1→3)-O-(2-acetamido-2-deoxy-α-d-galactopyranosyl)-l-serine, which is the common core structure of sugar chains of most mucins, the synthesis of these compounds was investigated. Koenigs-Knorr condensation of the 4,6-O-benzylidene derivative of O-(2-acetamido-2-deoxy-α-d-galactopyranosyl)-N-tosyl-l-serine methyl ester with 2,3,4,6-tetra-O-acetyl-α-d-galactopyranosyl bromide gave O-(2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-(1→3)-O-(2-acetamido-4,6-O-benzylidene-2-deoxy-α-d-galactopyranosyl)-N-tosyl-l-serine. Deacetylation, followed by acid hydrolysis of the benzylidene group, gave O-β-d-galactopyranosyl-(1 →3)-O-(2-acetamido-2-deoxy-α-d-galactopyranosyl)-N-tosyl-l-serine. A β anomer at the glycosidic linkage of the 2-acetamido-2- deoxy-d-galactose residue was also synthesized by the same procedure. Agaricus bisporus (mushroom) hemagglutinin was found to recognize the O-α-glycosyl linkage between 2-acetamido-2-deoxy-d-galactose and l-serine, in addition to the O-β-d-galactopyranosyl-(1→3)-2-acetamido-2-deoxy-d-galactose sugar sequence, for which Arachis hypogaea (peanut) and Bauhinia purpurea hemagglutinins were found to be specific. Ricinus communis hemagglutinin is more specific for the O-β-d-galactopyranosyl(1→4)-2-acetamido-2-deoxy-d-glucose (commonly found in serum glycoproteins) than for the O-β-d-galactopyranosyl-(1→3)-2-acetamido-2-deoxy-d-galactose sequence. With Wistaria floribunda hemagglutinin, not much difference in the inhibitory activities of these two sugar sequences was observed, and O-(2-acetamido-2-deoxy-α-d-galactopyranosyl)-N-tosyl-l-serine was the strongest inhibitor against this lectin. © 1979.