Rational Design of Activity-Based Retaining β-Exoglucosidase Probes

Activity-based probes (ABPs) have been developed for numerous serine hydrolases, cysteine proteases, and threonine hydrolases, but less frequently for other enzyme families. This chapter details the successful development and application of a number of activity-based retaining β-exoglucosidase probes. It discusses how, by rational design, suitable ABPs for retaining β-exoglucosidases can be designed. Mutations in the gene encoding glucosidase, beta, acid (GBA) can lead to partial malfunctioning of the enzyme, leading to accumulation of its substrate, glucosylceramide. This is in a nutshell the basis of the lysosomal storage disorder, Gaucher disease. The aziridine-based scaffold holds more promise, and as one can learn from Cazypedia, there are numerous retaining exoglycosidases that follow the general Koshland mechanism and that are, in principle, amenable to ABPP activity-based protein profiling using cyclitol aziridines emulating in configuration and substitution pattern the corresponding substrate glycosides.