Lysosomal GCase (glucocerebrosidase) activity assay

Here we report a method to measure enzyme activity of lysosomal glucocerebrosidase (GBA1, GCase) by monitoring the hydrolysis of the fluorescent substrate 4-methylumbelliferyl-β-D-glucopyranoside. The assay is performed at low pH, at which non-lysosomal glucocerebrosidase activity is expected to be low. This is consistent with the abolishment of 4-MUG hydrolysis in the presence of the GBA1 inhibitor CBE. Our data shows that GBA1 activity is significantly increased in purified lysosomes compared to the whole cell extract.