The substrate specificity and enzymatic sialylation ability of the bacterium α-2,6-sialyltransferase were examined. The enzyme assay displayed a remarkable ability to catalyze sialyl transfer to type-II oligosaccharides possessing fucoside or sialoside at the 2 or 3 position of the terminal galactoside. Enzymatic syntheses were performed in order to confirm the structure of unusual assay products found when using Neu5Ac β2,3Galβ1,4Glc and Fuc α1,2Galβ1,4Glc as the sialyl acceptors. Both sialylation reactions (10 μmol scales) were run using 83 munits of enzyme, were complete in 2 h, and afforded the sialoside analogues Neu5Ac α2,6(Fuc α1,2) Galβ1,4Glc (88%) and Neu5Ac α2,6(Neu5Ac β2,3) Galβ1,4Glc (92%).

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