Enzymatic fucosylations of non-natural sialylated type-I trisaccharides with recombinant fucosyl-transferase-III

Recombinant fucosyl-transferase-III (Lewis type enzyme) is used to prepare a series of non-natural sialyl-Lewis a derivatives on a preparative scale. The enzyme tolerates a wide range of acceptors which have the natural N-acetyl group of the glucosamine moiety replaced by substituted aromatic and hetero-aromatic amides. A recombinant fucosyl-transferase III is used to fucosylate a series of sialylLewis c-trisaccharides at the 4-OH of the N-acyl glucosamine unit to give a sialyl-Lewis a library with aromatic acyl residues.