Synthesis of unnatural sugar nucleotides and their evaluation as donor substrates in glycosyltransferase-catalyzed reactions Original Research Article

New unnatural sugar nucleotides, UDP-Fuc and CDP-Fuc were synthesized from fucose-β-1-phosphate and nucleotide monophosphates activated as morpholidates. Furthermore, a nucleotide analogue was prepared by phosphorylation of 1-(β-D-ribofuranosyl)cyanuric acid, itself obtained as a protected derivative by condensation of the persilylated derivative of cyanuric acid with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose in 74% yield. This phosphate activated according to the same procedure was condensed with fucose-β-1-phosphate, affording a new sugar nucleotide conjugate (NDP-Fuc) which was evaluated together with UDP-Fuc, CDP-Fuc and ADP-Fuc, as fucose donors in α-(1→4/3)-fucosyltransferase (FucT-III) catalyzed reaction. Fucose transfer could be observed with each of the donors and kinetic parameters were determined using a fluorescent acceptor substrate. Efficiency of the four analogues towards FucT-III was in the following order: UDP-Fuc = ADP-Fuc > NDP-Fuc > CDP-Fuc.