Assay Method Information
Assay Name:  Competition Binding Assay
Description:  Competition binding assays used herein were developed, validated and performed as described in Fabian et al., Nature Biotechnology 2005, 23, 329-336. Kinases were produced as fusions to T7 phage (See, Fabian et al. or WO04/015142) or alternatively, the kinases were expressed in HEK-293 cells and subsequently tagged with DNA for PCR detection (See, WO08/005310). For the binding assays, streptavidin-coated magnetic beads were treated with biotinylated affinity ligands for 30 min at room temperature to generate affinity resins. 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 binding. Binding reactions were assembled by combining kinase, liganded affinity beads, and test compounds in 1× binding buffer (20% SeaBlock, 0.17×PBS, 0.05% Tween 20, 6 mM DTT). Test compounds were prepared as 100× stocks in DMSO and rapidly diluted into the aqueous environment. DMSO was added to control assays lacking a test compound. Primary screen interactions were performed in polypropylene 384-well plates in a final volume of 34 μL, while Kd determinations were performed in polystyrene 96-well plates in a final volume of 135 μL. The assay plates were incubated at room temperature with shaking for 1 hour, long enough for binding reactions to reach equilibrium, and the affinity beads were washed extensively with wash buffer (1×PBS, 0.05% Tween 20) to remove unbound protein. The beads were then resuspended in elution buffer (1×PBS, 0.05% Tween 20, 2 μM non-biotinylated affinity ligand) and incubated at room temperature with shaking for 30 min. The kinase concentration in the eluates was measured by quantitative PCR. Each kinase was tested individually against each compound. KdS were determined using eleven serial threefold dilutions.
Affinity data for this assay
 
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