Competitive and Covalent Inhibitors of Human Lysosomal Retaining Exoglucosidases

Abstract

Deficiency in human acid glucosylceramidase (GBA1, a retaining β‐glucosidase) causes the lysosomal sphingolipid storage disorder Gaucher disease, whereas deficiency in human acid α‐glucosidase (GAA, a retaining α‐glucosidase) triggers the lysosomal glycogen storage disorder Pompe disease. Both enzymes process their substrate following a two‐step double‐displacement mechanism involving a covalent enzyme–substrate intermediate. Structural analysis of glycosidases complexed to substrates and inhibitors has provided insight into the reaction coordinates followed by glycosidases during catalytic hydrolysis and has assisted in the design of potent and selective inhibitors. Competitive and covalent inhibitors of both GBA1 and GAA have been developed in the past decades, for fundamental studies, as diagnostics tools, leads for drug development and therapeutic drugs for the clinical treatment of lysosomal storage diseases. Key Concepts The structural and functional diversity of glycoconjugates is reflected by the vast number of glycoprocessing enzymes encountered in all domains of life. Retaining glycosidases form a covalent intermediate during substrate processing, whereas inverting glycosidases do not. Competitive and covalent retaining glycosidase inhibitors exist, whereas inverting glycosidases can normally only be blocked by competitive inhibitors. Both covalent and competitive glycosidase inhibitors are found in nature and serve as inspiration for the design of synthetic inhibitors. Structural analysis of glycosidases complexed to substrates and inhibitors provides insight into the reaction coordinates followed by glycosidases during the catalytic cycle. Conformational analysis of the reaction coordinate of glycosidases is key in the design of potent and selective inhibitors. Glycosidase inhibitors may serve as leads for drug development. Activity‐based glycosidase probes can be applied in the discovery of glycosidase activities. Activity‐based probes are useful starting points for the development of diagnostics assays in disease areas in which glycosidase activities are involved. Genetic deficiency in glycosidases is the basis of numerous inherited disorders including Gaucher disease and Pompe disease.

Direct Stereoselective Aziridination of Cyclohexenols with 3‐Amino‐2‐(trifluoromethyl)quinazolin‐4(3H)‐one in the Synthesis of Cyclitol Aziridine Glycosidase Inhibitors

“…2,3‐Bis‐ O ‐benzyl‐D‐ gluco ‐cyclohexene ( 1a ), 7,4‐ O ‐benzylidene‐D‐ gluco ‐cyclohexene ( 2a ), perbenzylated D‐ gluco ‐cyclohexene ( 3a ),[4b] 2,3‐Bis‐ O ‐benzyl‐D‐ galacto ‐cyclohexene ( 4a ), 2,3‐Bis‐ O ‐benzyl‐conduritol cyclohexene ( 6a ), perbenzylated conduritol cyclohexene ( 7a ), 2,3‐Bis‐ O ‐benzyl‐D‐ xylo ‐cyclohexene ( 8a ),[8b] 2,3‐Bis‐ O ‐benzyl‐L‐ ido‐ cyclohexene ( 9a ) and perbenzylated L‐ ido‐ cyclohexene ( 10a ), 3‐amino‐2‐ethylquinazolin‐4(3 H )‐one, ( S )‐3‐amino‐2‐(1‐hydroxy‐2,2‐dimethylpropyl)quinazolin‐4(3 H )‐one and 3‐amino‐2‐(trifluoromethyl)‐2,3‐dihydroquinazolin‐4(1 H )‐one were synthesized following procedures previously described and their spectroscopic data are in agreement with those previously reported.…”

“…Cyclitol aziridines can mimic the conformation of the oxocarbenium ion transition state and irreversibly inactivate glycosidases by covalently reacting with the nucleophilic carboxylate (Figure B). Based on this virtue and the fact, as supported by several studies in recent years from our group, that covalent and irreversible inhibition is often both very effective and highly selective, cyclitol aziridines and their corresponding activity‐based probes (ABPs) are highly useful tools for chemical glycobiology research …”