CHEMBL5735876

Human, Dog and Rat c-Fms Enzyme Assay: Materials:Human c-fms protein (N-terminal 6His-tagged, amino acids 538-972), dog c-fms protein (N-terminal 6His-tagged, amino acids 535-967) and rat c-fms protein (N-terminal 6His-tagged, amino acids 536-978) were purified in-house using a HisTrap column. The Antibody Beacon tyrosine kinase assay kit was purchased from Life Technologies. The c-fms peptide substrate, SYEGNSYTFIDPTQ, and the phosphorylated product, SYEGNSpYTFIDPTQ, were obtained from American Peptide Company. Non-binding surface (NBS) 384-well plates were obtained from Corning.c-fms Enzyme Assay Procedure:In this assay, recombinant human, dog or rat c-fms catalyzed the phosphorylation of the FMS peptide substrate, SYEGNSYTFIDPTQ, with the phosphorylated product detected by a fluorescence immunoassay. The c-fms assay buffer consisted of 25 mM HEPES, pH 7.0, 5 mM MgCl2, 1 mM DTT and 0.01% Brj-35. 5 μl of 3× of the test compound(s) in assay buffer containing 1% DMSO were added to the wells of a 384-well NBS plate, at concentrations of 1 μM down to 0.00002 μM (applying a 1:3 dilution scheme). c-fms activity was assayed in the presence of 300 μM SYEGNSYTFIDPTQ, 1 mM ATP and human, dog or rat c-fms in a total volume of 15 μl. The reaction was initiated with ATP. The assay plates were sealed with aluminum sealing tape and incubated at room temperature for 2 h. At the end of the incubation, 5 μl of 4× detection reagent were added to each well (Antibody Beacon tyrosine kinase assay kit; the 4× detection reagent consisted of 100 nM Oregon Green 488 ligand and 200 nM anti-phosphotyrosine antibody and was prepared just prior to use). The plates were centrifuged at 1000×g for 1 min. Fluorescence was measured after 10 min on a Safire II reader at excitation/emission of 492/517 nm. RFU values were converted to micromolar phosphopeptide using a SYEGNSpYTFIDPTQ standard curve. IC50 values were calculated using GraphPad Prism 5.