Studies towards finding selective substrates for human β-glucosidases

Humans have three types of β-glucosidases (GBA) enzymes named GBA1, GBA2, and GBA3 that break down glucosylceramide (GlcCer). Studies have suggested that GBA2 is involved in Gaucher disease via feedback mechanism with GBA1, and lack of GBA2 activity leads to other neurodegenerative diseases. However, currently with no selective substrate probe developed for GBA2, making it difficult to study the enzyme activity, the role of GBA2 in pathogenesis of the diseases remains unclear. To find GBA2 selective substrates, the substrate specificity of GBA enzymes was investigated by preparing a series of mono-substituted deoxyfluoro and deoxy analogs of the substrate and testing the compounds with GBA enzymes to obtain Michaelis-Menten parameters, which allowed the evaluation of the affinity of each compound against each enzyme. This approach led to a compound that shows selectivity towards GBA2, which can be further developed into a cell lysate probe for brain cells.