| Assay Method Information | |
| | VEGFR2 Binding Assay |
| Description: | A competition binding assay (DISCOVERX KINOMESCAN ) 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 (Fabian, M. A. et al., 23 Nature Biotechnology 329-336 (2005); Karaman, M. W. et al., 26 Nature Biotechnology 127-132 (2008)).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.An 11-point dose response curve of 3-fold serial diluted test compound starting at 1 μM was used to determine the VEGFR2 binding constant (Kd). The compounds were prepared in 100% DMSO at 100× the final test concentration and the diluted to 1× in the assay for final DMSO concentration of 1%. Binding constants were calculated with standard dose-response curve using the Hill equation with Hill slope set to −1. Curves were fit using a non-linear least square fit with the Levenberg-Marquardt algorithm. |
| Affinity data for this assay | |
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