CHEMBL5735819

Recombinant Enzyme Assay - Time Dependence: Compounds were assessed for their ability to inhibit the enzymatic activity of a recombinant form of Glutaminase 1 (GAC) using a biochemical assay that couples the production of glutamate (liberated by GAC) to glutamate dehydrogenase (GDH) and measuring the change in absorbance for the reduction of NAD+ to NADH. Enzyme solution was prepared (50 mM Tris-HCl pH 8.0, 0.2 mM EDTA, 150 mM K2HPO4, 0.1 mg/ml BSA, 1 mM DTT, 10 ppm antifoam, 4 units/ml GDH, 4 mM adenosine diphosphate, and 4 nM GAC) and 50 μL added to a 96-well half area clear plate (Corning #3695). Compound (2 μL) was added to give a final DMSO concentration of 2% at 2× the desired concentration of compound. The enzyme/compound mix was sealed with sealing foil (USA Scientific) and allowed to incubate, with mild agitation, for 60 minutes at 20° C. Enzymatic reaction was started with the addition of 50 μL of substrate solution (50 mM Tris-HCl pH 8.0, 0.2 mM EDTA, 150 mM K2HPO4, 0.1 mg/ml BSA, 1 mM DTT, 20 mM L-glutamine, 2 mM NAD+, and 10 ppm antifoam) and read in a Molecular Devices M5 plate reader at 20° C. The plate reader was configured to read absorbance (λ=340 nm) in kinetic mode for 15 minutes. Data was recorded as milli-absorbance units per minute and slopes were compared to a control compound and a DMSO-only control on the same plate. Compounds with slopes less than the DMSO control were considered inhibitors and plate variability was assessed using the control compound.Results from this assay for several compounds are shown in Table 2, expressed as IC50, or half maximal inhibitory concentration, wherein IC50 is a quantitative measure indicating how much compound is needed to inhibit a given biological activity by half.