Assay Method Information

Assay Name:  Binding Assay
Description:  A competition binding assay was used to measure the ability of a compound to compete for binding of an immobilized adenosine triphosphosphate (ATP) site directed ligand using a DNA-tagged vascular endothelial growth receptor 2 (VEGFR2) as the target. The ability of the test compound to compete with the immobilized ligand was measured using quantitative polymerase chain reaction (qPCR) of the DNA tag. A VEGFR2 tagged T7 phage strain was prepared in an Escherichia coli (E. coli) derived from the BL21 strain. The E. coli were grown to log-phase, infected with VEGFR2 tagged T7 phage and then incubated with shaking at 32° C. until lysis. The lysate containing the kinase was then centrifuged and filtered to remove cell debris. Affinity resin for the VEGFR2 assay was prepared by treating Streptavidin-coated magnetic beads with a biotinylated small molecule ligand for 30 minutes at room temperature. The beads were blocked with excess biotin and then washed with blocking buffer SEABLOCK(PIERCE), 1% bovine serum albumin, 0.17% phosphate buffered saline, 0.05% TWEEN 20, 6 mM dithiothreitol). The binding reaction was initiated by combining in a well of a polystyrene 96-well plate, DNA tagged VEGFR2, liganded affinity beads and the serial diluted test compound in 1× binding buffer (20% SEABLOCK, 0.17× phosphate buffered saline, 0.05% TWEEN 20, 6 mM dithiothreitol) in a final volume of 0.135 ml. The assay plates were incubated at room temperature with shaking for 1 hour and then the beads were washed with wash buffer (1× phosphate buffered saline, 0.05% TWEEN 20). The beads were re-suspended in elution buffer (1× phosphate buffered saline, 0.05% TWEEN 20, 0.05 μM non-biotinylated affinity ligand) and incubated at room temperature with shaking for 30 minutes. The VEGFR2 concentration in the eluate was measured using qPCR.
Affinity data for this assay
 

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