CHEMBL5734685

Enzymatic Assay: PARP-1 enzymatic assay was conducted using a method modified from HT F Homogeneous PARP Inhibition Assay Kit (Trevigen). 8.8 nM PARP-1 was pre-incubated with different concentrations of compounds in a buffer containing 100 mM Tris-HCl pH 8.0, 100 mM NaCl, 20 mM MgCl2, and 1% DMSO for 30 min at RT. The auto-PARylation reaction was initiated by addition of 500 nM NAD and 20 ng/ul activated DNA (Sigma) and incubated at RT for 40 min. The remaining NAD was detected by incubation with cycling assay solution containing 1% ethanol, 0.30 U/ml alcohol dehydrogenase, 25 uM resazurin, and 0.25 U/ml diaphorase for 50 min at RT. The concentration of NAD is proportional to the fluorescence signal at Ex540 nm/Em 590 nm. The IC50s were calculated based on residual enzyme activity (the rate of NAD decrease) in presence of increasing concentrations of compounds.