Assay Method Information

Assay Name:  NIK Enzyme Inhibition Assay
Description:  The ability of the nuclear factor-kappa B (NF-kB)-inducing kinase (NIK) to catalyze the hydrolysis of adenosine-5′-triphosphate (ATP) was monitored using the Transcreener ADP (adenosine-5′-diphosphate) assay (BellBrook Labs). Purified NIK (0.5 nM) derived from a baculovirus-infected insect cell expression system was incubated with test compounds for 1-3.5 hours in 50 mM 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid buffer (pH 7.2) containing 10 mM MgCl2, 2 mM dithiothreitol, 10 μM ATP, 0.01% Triton X-100, 0.1% gamma-globulins from bovine blood, 1% dimethylsulfoxide (DMSO), 7 μg/mLADP antibody and 5 nM ADP-MR121 633 tracer. Reactions were quenched by the addition of 20 mM 2,2′,2″,2′″-(ethane-1,2-diyldinitrilo)tetraacetic acid and 0.01% Brij 35. The tracer bound to the antibody was displaced by the ADP generated during the NIK reaction, which causes a decrease in fluorescence polarization that was measured by laser excitation at 633 nm with a Fluorescence Correlation Spectroscopy Plus reader (Evotec AG). Equilibrium dissociation constant (Ki) values for NIK inhibitors are calculated from plots of activity vs. inhibitor concentration using Morrison's quadratic equation that accounts for the potential of tight binding, and by also applying the conversion factor that accounted for competitive inhibition and the concentration of substrate used in the assay relative to its Michaelis constant (Km).
Affinity data for this assay
 

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