Chemoenzymatic synthesis of 6-phospho-cyclophellitol as a novel probe of 6-phospho-beta-glucosidases

Covalent, mechanism-based inhibitors of glycosidases are valuable probe molecules for visualizing enzyme activities in complex systems. We, here, describe the chemoenzymatic synthesis of 6-phospho-cyclophellitol and evaluate its behaviour as a mechanism-based inactivator of the Streptococcus pyogenes 6-phospho-beta-glucosidase from CAZy family GH1. We further present the three-dimensional structure of the inactivated enzyme, which reveals the constellation of active site residues responsible for the enzyme's specificity and confirms the covalent nature of the inactivation.