CHEMBL5736327

Measurement of Inhibitory Effect on FGFR1 Kinase Activity: When setting conditions for the measurement of the inhibitory effect of the compounds on FGFR1 kinase activity, a biotinylated peptide (biotin-EEPLYWSFPAKKK) was synthesized for use as a substrate by utilizing the amino acid sequence of FL-Peptide 22 (Caliper Life Sciences, Inc.) with biotin. The purified recombinant human FGFR1 protein used in the test was purchased from Carna Biosciences, Inc. In the measurement of the inhibitory effect of the compounds, first, a test compound was gradually diluted with dimethylsulfoxide (DMSO) to a concentration 20 times higher than the final concentration. Next, the purified human FGFR1 protein, substrate peptide (final concentration: 250 nM), magnesium chloride (final concentration: 5 mM), ATP (final concentration: 190 μM), and the test compound DMSO solution (final concentration of DMSO: 5%) were added to a reaction buffer (15 mM Tris-HCl pH 7.5, 0.01% Tween-20, 2 mM DTT), and the mixture was incubated at 25° C. for 120 minutes to perform a kinase reaction. EDTA was added thereto to a final concentration of 40 mM to thereby terminate the reaction. Then, a detection solution containing Eu-labeled anti-phosphorylated tyrosine antibody PT66 (PerkinElmer) and SureLight APC-SA (PerkinElmer) was added, and the resulting mixture was allowed to stand at room temperature for 2 hours or more. Finally, the intensity of fluorescence when excitation light with a wavelength of 337 nm was irradiated was measured by a PHERAstar FS (BMG LABTECH) at two wavelengths of 620 nm and 665 nm. The amount of phosphorylation was determined from the fluorescence intensity ratio of the two wavelengths. The compound concentration at which phosphorylation was inhibited by 50% was defined as the IC50 value (nM).