CHEMBL5731716

SPA Assay: The assays were performed in U-bottom 384-well optiplates. The final assay volume was 15 μl prepared from 7.5 μl additions of microsomes (prepared as a high-speed pellet from homogenized HEK2 cells stably transfected with CYP17), substrates (3H-Pregnenolone and NADPH) and test compounds in assay buffer (50 mM Potassium phosphate pH 7.2, 10% glycerol). The reaction was initiated by the combination of the microsomes and substrates in wells containing compound. The reaction was incubated at room temperature for 45 minutes and terminated by adding 7.5 μl of 0.2N HCl to each well. Following an incubation period of 10 minutes, anti-DHEA-coated SPA beads were added to the terminated reaction. The plate was sealed and incubated overnight with shaking at 4° C. The beads were allowed to settle in the plate for 1 hour and the plate read on a TOPCOUNT® (Perkin-Elmer) plate reader.Inhibition data were calculated by comparison to no enzyme control reactions for 100% inhibition and vehicle-only reactions for 0% inhibition. The final concentration of reagents in the assays are NADPH, 2 mM; 3H-Pregnenolone, 1 uM; microsomes, 1.25 ug/ml; Anti-DHEA-SPA beads (0.125 mg/well) in 0.5% Triton X-100 and DMSO, 0.05%. Dose response curves were generated to determine the concentration required inhibiting 50% of enzyme activity (IC50). Compounds were dissolved at 10 mM in dimethylsulfoxide (DMSO) and evaluated at eleven concentrations, each in duplicate. IC50 values were derived by non-linear regression analysis.