The ?-Thioglycoligase Derived from a GH89 ?-N-Acetylglucosaminidase Synthesises ?-N-Acetylglucosamine-Based Glycosides of Biomedical Interest

We report here on the preparation of a novel ?-thioglycoligase that can be used for the fast and efficient synthesis of ?-N-acetylglucosamine-based glycosides. Using the ?-N-acetyl-glucosaminidase from Clostridium perfringens of family GH89 (according to the Carbohydrate Active Enzymes classification) as starting point, we prepared mutants in the acid/base residue glutamic acid 483 that were found to have different synthetic efficiencies (maximal yields >80% after 24 h) in the presence of an activated donor and suitable acceptors. The synthetic potential of the Glu483 alanine mutant as an ?-thioglycoligase - only the third biocatalyst with this stereospecificity reported to date, and the first selective for the N-acetylglucosamine moiety - was demonstrated by producing for the first time N-acetyl-?-d-glucosaminyl azide and N-acetylglucosamine ?-thioglycosides in high yields. To showcase the application of such compounds, we show that they offer the wild-type CpGH89 protection from thermal unfolding, demonstrating their potential as pharmacological chaperones for the treatment of mucopolysaccharidosis IIIB (Sanfilippo syndrome). (Figure presented.).