Enzymatic syntheses of T antigen-containing glycolipid mimicry using the transglycosylation activity of endo-α-N-acetylgalactosaminidase Original Research Article

Thomsen–Friedenreich antigen (T antigen) disaccharide, β-d-galactose-(1→3)-α-N-acetyl-d-galactosamine (β-d-Gal-(1→3)-α-d-GalNAc), containing glycolipid mimicry was synthesized using the transglycosylation activity of endo-α-N-acetylgalactosaminidase from Bacillus sp. This enzyme could transfer the disaccharide from a p-nitrophenyl substrate to water-soluble 1-alkanols and other alcohols at a transfer ratio of 70% or more. Although the transfer ratios were lower for water-insoluble than water-soluble alcohols, they were shown to increase by adding sodium cholate to the reaction mixtures. The enzyme also transferred the disaccharide directly from asialofetuin to 1-alkanols. The anomeric bond between the disaccharide and 1-alkanols of the transglycosylation product is in the α configuration as determined by sequential digestion of jack bean β-galactosidase and Acremonium α-N-acetylgalactosaminidase. Since the transglycosylation product, β-d-Gal-(1→3)-α-d-GalNAc-(1→O)-hexyl, efficiently inhibits the binding of anti-T antigen monoclonal antibody to asialofetuin, it has potential as an agent for blocking T antigen-mediated cancer metastasis.