| Assay Method Information | |
| | Enzymatic Assay for Inhibition of PARP7 |
| Description: | Displacement of Probe A, a biotinylated probe binding to the TIPARP active site, was measured using a time-resolved fluorescence energy transfer (TR-FRET) assay. 20 nL of a dose response curve of each test compound was spotted in black 384-well polystyrene proxiplates (Perkin Elmer) using a Mosquito (TTP Labtech). Reactions were performed in a 8 μL volume by adding 6 μL of TIPARP and Probe A in assay buffer (20 mM HEPES pH=8, 100 mM NaCl, 0.1% bovine serum albumin, 2 mM DTT and 0.002% Tween20), incubating with test compound at 25° C. for 30 min, then adding 2 μL of ULight-anti 6×His and LANCE Eu-W1024 labeled streptavidin (Perkin Elmer). The final concentrations of TIPARP and Probe A were 6 nM and 2 nM, respectively. The final concentration of ULight-anti 6xHis and LANCE Eu-W1024 labeled streptavidin were 4 nM and 0.25 nM, respectively. Reactions were incubated at 25° C. for an additional 30 min, then read on an Envision platereader equipped with a LANCE/DELFIA top mirror (Perkin Elmer) using excitation of 320 nm and emission of 615 nm and 665 nM with a 90 μs delay. The ratio of the 665/615 nm emission were calculated for each well to determine the amount of complex of TIPARP and Probe A in each well. Control wells containing a negative control of 0.25% DMSO vehicle or a positive control of 100 μM Example 190 were used to calculate the % inhibition as described below:% inhibition = 100 × TRF cmpd - TRF min TRF max - TRF minwhere TRFcmpd is the TR-FRET ratio from the compound treated well, TRFmin is the TR-FRET ratio from the Example 190-treated positive control well and TRFmax is the TR-FRET ratio from the DMSO-treated negative control well.The % inhibition values were plotted as a function of compound concentration and the following 4-parameter fit was applied to derive the IC50 the values:Y = Bottom + ( Top - Bottom ) ( 1 + ( X IC 50 ) Hill Coefficientwhere top and bottom are normally allowed to float, but may be fixed at 100 or 0 respectively in a 3-parameter fit. The Hill Coefficient is normally allowed to float but may also be fixed at 1 in a 3-parameter fit. Y is the % inhibition and x is the compound concentration. |
| Affinity data for this assay | |
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