CHEMBL5737324

Enzymatic Assay: un-Phosphorylated (UP): The inhibitor potency of the exemplified compounds was determined in an enzyme discontinuous assay that measures peptide phosphorylation using FRET measurements to detect product formation. Inhibitors were serially diluted in DMSO and a volume of 0.2 μL was transferred to the wells of a 384-well plate. For the isoforms of FGFR (−1, −2, −3 wild-type and mutant isoforms, −4) including un-phosphorylated (UP)proteins, a 5 μL/well volume of enzyme diluted in assay buffer (50 mM HEPES, 10 mM MgCl2, 1 mM EGTA, 0.01% Tween-20, 5 mM DTT, pH 7.5) was added to the plate and pre-incubated with inhibitor for 5 to 15 minutes at ambient temperature. Appropriate controls (enzyme blank and enzyme with no inhibitor) were included on the plate. The reaction was initiated by the addition of a 5 μL/well volume containing both biotinylated EQEDEPEGDYFEWLE (SEQ ID: 1) peptide substrate and ATP in assay buffer. The 10 μL/well reaction concentration of the peptide substrate was 500 nM whereas the ATP concentration was maintained near or below the ATP Km for each FGFR isoform. The ATP Km values were pre-determined for each FGFR isoform in a separate series of experiments. The reaction plate was incubated at 25° C. for 1 hr and the reactions were ended with the addition of 5 μL/well of quench solution (50 mM Tris, 150 mM NaCl, 0.5 mg/mL BSA, pH 7.8; 45 mM EDTA, 600 nM staurosporin, with Perkin Elmer Lance Reagents at 3.75 nM Eu-antibody PY20 and 180 nM APC-Streptavidin). The plate was allowed to equilibrate for −10 minutes at ambient temperature before scanning on a PheraStar plate reader (BMG Labtech) instrument.