Assay Method Information

Assay Name:  Enzyme Inhibition Assay
Description:  Quizartinib (Ambit Biosciences Corporation) was used as Reference Compound 1.6 μL (0.75 ng) of a mutant FLT3 protein (FLT3 D835Y, Life Technologies) and 3 μL of a solution (100 mmol/L HEPES, 10 mmol/L MgCl2, 25 mmol/L NaCl, 0.01% BSA, 1 mmol/L DTT, pH 7.5) containing a predetermined concentration of a test compound were mixed and allowed to incubate at 25° C. for 15 minutes. Thereafter, 3 μL (final concentration: 0.25 μmol/L) of a substrate peptide Biotin-AAA-AEEEEYFELVAKKK (Toray Industries, Inc.) (SEQ ID NO: 2) and 3 μL (final concentration: 15 μmol/L) of ATP (Sigma-Aldrich) were respectively added thereto, followed by shaking for 2 minutes and further allowing to incubate at 25° C. for 40 minutes to carry out an enzymatic reaction. It should be noted that FLT D835Y refers to an FLT3 protein with a substitution of aspartic acid 835 to tyrosine.Then, 30 μL of an enzyme reaction stop solution (5 μg/mL Streptavidin, 0.19 μg/mL PT66-K, 30 μmol/L HEPES (pH 7.0), 150 mmol/L KF, 75 mM EDTA, 0.15% BSA, 0.075% Tween20) containing Streptavidin-Xlent (Cisbio) and Mab PT66-K (Cisbio) was added to stop the enzymatic reaction, followed by allowing to incubate at room temperature for 1 hour to carry out an antigen-antibody reaction. Thereafter, phosphorylation of the substrate peptide was measured by measuring the time-resolved fluorescence of 615 nm and 665 nm using an Envision (PerkinElmer). By taking the value obtained by dividing the fluorescence value at 665 nm by the fluorescence value at 615 nm as a measured value, taking the measured value of the well with no addition of the compound (DMSO treatment only) and addition of ATP as 0% inhibition, and taking the measured value of the well with no addition of the compound (DMSO treatment only) and no addition of ATP as 100% inhibition, a 50% inhibitory concentration (IC50 value) of the test compound was calculated by Fit Model 205 of XLfit Ver. 5.3.1 (ID Business Solutions Limited).
Affinity data for this assay
 

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