Exploring the Synthetic Application of Helicobacter pylori α1,3/4-Fucosyltransferase FucTIII toward the Syntheses of Fucosylated Human Milk Glycans and Lewis Antigens

In this study, we focused on the synthetic application of alpha 1,3/4-fucosyltransferase obtained from Helicobacter pylori DSM 6709 (FucTIII) on L-fucose-containing glycans. By combining FucTIII with the sequential one-pot enzymatic system of human milk oligosaccharide (HMO) production, various fucosylated HMOs, such as lacto-N-fucopentose V (LNFP V), LNFP VI, lacto-N-difucohexaose II (LNDFH II), and lacto-N-neodifucohexaose II (LNnDFH II), were synthesized. Moreover, L-fucose-containing glycan synthesis of Lewis antigens, such as Lewis x, Lewis y, Lewis a, Lewis b, sialyl Lewis x, sialyl Lewis a, and their derivatives, was achieved. Enzyme kinetics proved that the catalytic efficiency (k(cat)/K-m) of FucTIII on type-2 N-acetyl lactosamine (LacNAc) was 39 times higher than that on type-1 LacNAc. Furthermore, enzyme kinetics revealed that additional GIcNAc on the nonreducing end of the acceptors can enhance the catalytic efficiency of FucTIII on the glycan acceptors. Investigations of bacterial FucTs on substrate spectra indicate that future studies should study expansion of the inventory of biocatalysis for the synthesis of valuable glycans.