CHEMBL5734161

IRAK4 Enzymatic DELFIA Assay, Protocol A: This is an in vitro assay to measure IRAK4 enzymatic activity utilizing the DELFIA (Dissociation-Enhanced Lanthanide Fluorescent Immunoassay, Perkin-Elmer) platform, with the human IRAK4 FL (Full Length) construct to characterize IRAK4 inhibitor and control compounds at 0.6 mM ATP (KM). The final amount of enzyme in the assay is 0.1 nM IRAK4 FL, final concentration of substrate is 50 nM, and final concentration of DMSO is 2.5%.The test compound was solubilized in DMSO to a stock concentration of 30 mM. The dose response plates were prepared with a 4 mM primary compound concentration, and then diluted in DMSO in a four-fold series for a total of 11 data points. Compounds were prepared as a 40-fold multiple of the final in-assay concentration.To begin the assay, 19 μL of reaction mixture containing 20 mM HEPES pH=7.5, 5 mM MgCl2, 0.0025% Brij-35, 600 μM ATP, 0.21 nM Full-length phosphorylated recombinant human IRAK4 (GenBank ID AF445802) were aliquoted into Ultra-Clear Polypropylene, 384-well, U-Bottom Plates (Corning Life Sciences). 1 μL of test compound from the dose-response plate was added to the reaction mixture and incubated for 20 minutes at room temperature. Then 20 μL of 20 mM HEPES pH=7.5, 5 mM MgCl2, 0.0025% Brij-35, 600 μM ATP, and 100 nM ERM-biotinylated peptide (AGAGRDKYKTLRQIR) was added to start the reaction. The reaction was incubated for 60 minutes at room temperature and stopped by the addition of 20 μL 0.3M EDTA.50 μL of the reaction mixture was transferred to a streptavidin coated detection plate (DELFIA streptavidin coated plates, 384-well, white plates, Perkin-Elmer Life Sciences) and incubated for 30 minutes at room temperature. The plates were washed 4× with 75 μL per well of PBS containing 0.05% Tween-20. Plates were then incubated with 50 μL per well of antibody cocktail of Anti-pERM antibody at 0.125 μg/mL (Cell Signaling Technology), plus Anti-Rabbit IgG EuN1 at 0.25 ug/ml (Perkin-Elmer Life Sciences) in a solution of 10 mM MOPS pH=7.5, 150 mM NaCl, 0.05% Tween-20, 0.02% NaN3, 1% BSA, 0.1% Gelatin for 45 minutes. The plates were washed 4× with 50 μL per well of PBS containing 0.05% Tween-20. Then 50 μL per well of DELFIA Enhancement Solution (Perkin-Elmer Life Sciences) were added to the plate and then read on an EnVision Model 2103 using a 340 nm excitation wavelength and a 665 nm emission wavelength for detection.