Assay Method Information

Assay Name:  Biochemical Assay
Description:  A Z′-Lyte assay based on a fluorescence resonance energy transfer (FRET) readout was developed for measuring IRAK4-dependent phosphorylation of a FRET-peptide substrate as described by Thermo Fisher Scientific (Grand Island, N.Y.). At a starting concentration of 1.5 mM, the identified compounds were serially diluted with 100% dimethyl sulfoxide (DMSO) in 3-fold increments, into Greiner bio-one 96-well plates (cat. #: 650201, Greiner bio-one, Monroe, N.C.). Compounds were then transferred to intermediate Greiner bio-one 96-well plates and diluted 10-fold with Kinase assay buffer (25 mM HEPES, pH 7.5, 10 mM MgCl2, 10 mM MnCl2, 1 mM EGTA, and 0.01% Brij-35, 2 mM DTT). Three μL of the serially diluted compounds were then transferred in duplicate to low-volume 384-well black proxiplates (cat. #: 6008269; Perkin Elmer, Akron, Ohio), to give duplicate twelve-point concentration curves. Six μl of a 2.5× solution of IRAK4 enzyme (cat #: 40064, BPS Bioscience, San Diego, Calif.) in kinase buffer was added to each well, followed by a 10 minutes pre-incubation step. Reactions were initiated by adding 6 μl of a 2.5× substrate mix of ATP and Z′-Lyte Ser/Thr 7 peptide (cat. #: PV3180, Thermo Fisher Scientific, Grand Island, N.Y.) and proceeded at room temperature for 1 hour. The final concentration of key reagents in the 15 uL kinase reactions were 2 μM substrate, 2 nM enzyme, and 1 mM ATP, with dose responses starting at 30 μM compound. At the end of the kinase reactions, 5 μl of developing solution (as instructed in for cat. #: PV3180, Thermo Fisher Scientific, Grand Island, N.Y.) was added to each well and incubated at room temperature for 1 hour. All wells were read on an Envision 2105 Multilabel fluorescence plate reader (Perkin Elmer, Waltham, Mass.) at 400 nm excitation and 460 nm/530 nm emission. Plus and minus 100% inhibition controls were used to calculate percent inhibition and IC50 curves were generated using Graphpad Prism (La Jolla, Calif.).
Affinity data for this assay
 

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