| Assay Method Information | |
| | BROMOscan Binding Assay |
| Description: | A BROMOscan binding assay was utilized to test the in vitro binding activity of (S)-Compounds 1, 2, 3, 4, 5 and 7 to the first and second bromodomains (BRD4(1) and BRD4(2)), separately, of Brd4. (S)-JQ (S8) was used as a positive control.T7 phage strains displaying bromodomains were grown in parallel in 24-well blocks in an E. coli host derived from the BL21 strain. E. coli were grown to log-phase and infected with T7 phage from a frozen stock (multiplicity of infection=0.4) and incubated with shaking at 32° C. until lysis (90-150 minutes). The lysates were centrifuged (5,000×g) and filtered (0.2 μm) to remove cell debris. Streptavidin-coated magnetic beads were treated with biotinylated small molecule or acetylated peptide ligands for 30 minutes at room temperature to generate affinity resins for bromodomain assays. The liganded beads were blocked with excess biotin and washed with blocking buffer (SeaBlock (Pierce), 1% BSA, 0.05% Tween 20, 1 mM DTT) to remove unbound ligand and to reduce non-specific phage binding.Binding reactions were assembled by combining bromodomains, liganded affinity beads, and test compounds in 1× binding buffer (17% SeaBlock, 0.33×PBS, 0.04% Tween 20, 0.02% BSA, 0.004% Sodium azide, 7.4 mM DTT). Test compounds were prepared as 1000× stocks in 100% DMSO and subsequently serially diluted 1:10 in monoethylene glycol (MEG) to create stocks at 100× the screening concentration (resulting stock solution is 10% DMSO/90% MEG). The compounds were then diluted directly into the assays such that the final concentration of DMSO and MEG were 0.1% and 0.9%, respectively. All reactions were performed in polystyrene 96-well plates in a final volume of 0.135 ml. The assay plates were incubated at room temperature with shaking for 1 hour and the affinity beads were washed with wash buffer (1×PBS, 0.05% Tween 20). The beads were then re-suspended in elution buffer (1×PBS, 0.05% Tween 20, 2 μM nonbiotinylated affinity ligand) and incubated at room temperature with shaking for 30 minutes. The bromodomain concentration in the eluates was measured by qPCR. |
| Affinity data for this assay | |
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