| Assay Method Information | |
| | FGFR Enzymatic Assay |
| Description: | 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. A 5 μL/well volume of enzyme isoforms of FGFR (−1, −2, −3 wild-type and mutant isoforms, −4) including phosphorylated and un-phosphorylated proteins 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 peptide substrate (SEQ ID NO: 1) 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. The ATP Km values were pre-determined 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.Either GraphPad prism or XLfit was used to analyze the data. The IC50 values were derived by fitting the data to a four parameter logistic equation producing a sigmoidal dose-response curve with a variable Hill coefficient. Prism equation: Y=Bottom+(Top−Bottom)/(1+10{circumflex over ( )}((Log IC50−X)*Hill slope)); XLfit equation: Y=(A+((B−A)/(1+((X/C){circumflex over ( )}D)))) where X is the logarithm of inhibitor concentration and Y is the response. |
| Affinity data for this assay | |
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