| Assay Method Information | |
| | CK2 Kinase Assay |
| Description: | The effectiveness of compounds of the present invention as inhibitors of protein kinases can be readily tested by assays known to those skilled in the art. For example, in vitro protein kinase assays may be conducted with a relevant purified protein kinase and an appropriate synthetic substrate to determine the inhibitory activity of the compounds. Assays for inhibition of CK2 by the instant compounds were performed in 384-well plates with reaction mixtures containing 10 μM of peptide substrate (RRRADDSDDDDD-NH2), [γ-33P]ATP (10 μCi) at 25 μM (CK2A1) or 5 μM (CK2A2), 20 mM Hepes (pH 7.4), 100 mM NaCl, 10 mM MgCl2, 0.25 mM dithiothreitol, Brij-35 at 0.015%, and recombinant CK2A1 (10 nM, Invitrogen) or CK2A2 (5 nM, Upstate Biotechnology). Reaction mixtures were incubated at 30° C. for 1 hour, and reaction products were captured by binding to phosphocellulose (P81) filter plates. Incorporation of radioactive phosphate into the peptide substrate was determined by liquid scintillation counting. The potency of compounds in inhibiting CK2 is expressed as IC50, defined as the concentrations of compounds required to inhibit the enzymatic activity by 50%.The inhibitory activity of the instant compounds may also be measured by recombinant CK2 holoenzyme kinase assays. The assays were performed in U-bottom 384-well plates. The final assay volume was 30 μl prepared from 15 μl additions of enzyme and substrates (fluoresceinated peptide FL-RRRADDSDDDDD-NH2 and ATP) and test compounds in assay buffer (20 mM HEPES pH 7.4, 10 mM MgCl2, 100 mM NaCl, 0.015% Brij35 and 0.25 mM DTT). The reaction was initiated by the combination of bacterially expressed, CK2 α/β or CK2 α′/β holoenzyme with substrates and test compounds. The reaction was incubated at room temperature for 60 minutes and terminated by adding 30 μl of 35 mM EDTA to each sample. The reaction mixture was analyzed on the Caliper LABCHIP 3000 (Caliper, Hopkinton, Mass.) by electrophoretic separation of the fluorescent substrate and phosphorylated product. 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 CK2 α/β assay was 25 μM ATP, 1.5 μM FL-RRRADDSDDDDD-NH2, 50 pM CK2 α/β holoenzyme, and 1.6% DMSO. The final concentration of reagents in the CK2 α′/β assay was 10 μM ATP, 1.5 μM FL-RRRADDSDDDDD-NH2, 100 pM CK2 α′/β holoenzyme, and 1.6% DMSO. Dose response curves were generated to determine the concentration required inhibiting 50% of kinase activity (IC50). Compounds were dissolved at 10 mM in dimethylsulfoxide (DMSO) and evaluated at eleven concentrations. IC50 values were derived by non-linear regression analysis. |
| Affinity data for this assay | |
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