CHEMBL5735904

Inhibitory Activity Assay: The kinase activity was measured using QuickScout Screening Assist (trademark) MSA (commercially available kit manufactured by Carna Biosciences, Inc.) by mobility shift assay (MSA) method. The substrate of the kinase reaction was an FITC-labeled SRCtide peptide included in the kit. An assay buffer [20 mM HEPES, 0.01% Triton X-100 (trademark), 2 mM dithiothreitol, pH 7.51 was used and adjusted at 4 uM substrate, 20 mM MgCl2 and 120 um and 100 um ATP, which are ATP concentrations close to Km value of wild type and C481S mutant BTK respectively, to obtain a substrate mixture solution. The enzyme solution was also prepared by diluting the wild type or C481S mutant BTK to 0.28 nM using the assay buffer. The 10 mM solution of the test compound in DMSO was further diluted with DMSO to 10 levels of the concentration (0.00003 mM, 0.0001 mM, 0.0003 mM, 0.001 mM, 0.003 mM, 0.01 mM, 0.03 mM, 0.1 mM, 0.3 mM, 1 mM), each of which was subjected to a 25-fold dilution with the assay buffer to obtain the drug solutions (4% DMSO solutions). 5 uL of the drug solution or a control solution (4% DMSO-assay buffer), 5 uL of the substrate mixture solution, and 10 uL of the enzyme solution were mixed in the wells of a polypropylene 384-well plate and allowed to react at room temperature for 1 hour, and then quenched by adding 60 ??L of the termination buffer included in the kit. Subsequently, the quantities of the substrates (S) and the phosphorylated substrate (P) in the reaction solution were measured using LabChip EZ Reader II system (manufactured by Caliper Life Sciences) according to the protocol of the assay kit.