Synthesis of 4-Azido-<i>N</i>-acetylhexosamine Uridine Diphosphate Donors: Clickable Glycosaminoglycans

Abstract

Unnatural chemically modified nucleotide sugars UDP-4-N₃-GlcNAc and UDP-4-N₃-GalNAc were chemically synthesized for the first time. These unnatural UDP sugar products were then tested for incorporation into hyaluronan, heparosan, or chondroitin using polysaccharide synthases. UDP-4-N₃-GlcNAc served as a chain termination substrate for hyaluronan or heparosan synthases; the resulting 4-N₃-GlcNAc-terminated hyaluronan and heparosan were then successfully conjugated with Alexa Fluor 488 DIBO alkyne, demonstrating that this approach is generally applicable for labeling and detection of suitable glycosaminoglycans.