Activity-based probes for retaining β-glucosidases: Novel tools for research and diagnostics

The glycosylhydrolase glucocerebrosidase (GBA) cleaves the β-D-glucose moiety from one of the simplest glycosphingolipids, glucosylceramide, in the lysosome. Deficiency of GBA results in accumulations of glycosylceramide, primarily in macrophages, provoking Gaucher disease. The expression of this disease is remarkably variable, as heterogeneity among identical twins has even been reported. Moreover, correlation between in vitro GBA activity and the Gaucher phenotype is not very strict, suggesting additional factors influence the residual activity of GBA in situ. Registered treatments comprise of enzyme supplementation therapy employing exogenously produced GBA, and substrate reduction therapy, utilizing inhibitors for the glucosylceramide synthase. Recently, the use of small chemical chaperones, thought to stabilize mutant GBA in situ, has received major attention. The research described in this thesis addresses the present lack of suitable methods to visualize (active) GBA molecules in situ, as it proves a major limitation in fundamental research on GBA, Gaucher disease, the development of new treatments including chemical chaperone therapy, but also the creation of a technological fundament of similar methodologies for related glycosylhydrolases and their associated diseases.