CHEMBL3888751

Fluorescence Polarization Competition Immunoassay: An autophosphorylation, fluorescence polarization competition immunoassay was used to determine the potency for c-fms inhibition exhibited by selected compounds of Formula I. The assay was performed in black 96-well microplates (LJL BioSystems). The assay buffer used was 100 mM 4-(2-hydroxyethyl)piperazine 1-ethanesulfonic acid (HEPES), pH 7.5, 1 mM 1,4-dithio-DL-threitol (DTT), 0.01% (v/v) Tween-20. Compounds were diluted in assay buffer containing 4% dimethylsulfoxide (DMSO) just prior to the assay. To each well, 5 μL of compound were added followed by the addition of 3 μL of a mix containing 33 nM c-fms (Johnson & Johnson PRD) and 16.7 mM MgCl2 (Sigma) in assay buffer. The kinase reaction was initiated by adding 2 μL of 5 mM ATP (Sigma) in assay buffer. The final concentrations in the assay were 10 nM c-fms, 1 mM ATP, 5 mM MgCl2, 2% DMSO. Control reactions were ran in each plate: in positive and negative control wells, assay buffer (made 4% in DMSO) was substituted for the compound; in addition, positive control wells received 1.2 μL of 50 mM ethylenediaminetetraaceticacid (EDTA). The plates were incubated at room temperature for 45 min. At the end of the incubation, the reaction was quenched with 1.2 μL of 50 mM EDTA (EDTA was not added to the positive control wells at this point; see above). Following a 5-min incubation, each well received 10 μL of a 1:1:3 mixture of anti-phosphotyrosine antibody, 10×, PTK green tracer, 10× (vortexed), FP dilution buffer, respectively (all from PanVera, cat. #P2837). The plate was covered, incubated for 30 min at room temperature and the fluorescence polarization was read on the Analyst. The instrument settings were: 485 nm excitation filter; 530 nm emission filter; Z height: middle of well; G factor: 0.93. Under these conditions, the fluorescence polarization values for positive and negative controls were approximately 300 and 150, respectively, and were used to define the 100% and 0% inhibition of the c-fms reaction.