Substrate specificity of fucosyl transferase III: An efficient synthesis of sialyl Lewis x -, sialyl Lewis a - derivatives and mimetics thereof

Fucosyl transferase III (FucT III) has previously been characterized as the most general enzyme of the FucT family, as judged from its ability to catalyze the transfer of fucose to both Galβ(1-3)GlcNAc and Galβ(1-4)GlcNAc. In order to explore the synthetic potential of FucT III for the enzymatic synthesis of sialyl Lewisx and sialyl Lewisa derivatives, its substrate specificity has been probed using a number of natural substrate mimetics. A remarkable range of acceptor substrates was found when N-acetyl glucosamine was replaced by D-glucal, (R,R)-1,2-cyclohexanediol and (R,R)-butan-2,3-diol. Although the reaction rates were low compared to the reaction with the natural substrates, they proved to be sufficient for the synthesis of preparative amounts.Key words: fucosyl transferase III, sialyl Lewisa, sialyl Lewisx, carbohydrate mimetics.