| Assay Method Information | |
| | Kinase Homogeneous Time-Resolved Fluorescence Assay |
| Description: | The N-terminally His6-tagged recombinant kinase domain of the human c-Met (amino acids 960-1390), expressed in insect cells (SF21) and purified by Ni-NTA affinity chromatography and consecutive size exclusion chromatography (Superdex 200), is used. Alternatively, commercially available c-Met (Millipore) can be used. As substrate for the kinase reaction, the biotinylated poly-Glu, Tyr (4:1) copolymer (#61GTOBLC, Cis Biointernational, Marcoule, France) is used. For the assay, 50 mL of a 100-fold concentrated solution of the test compound in DMSO is pipetted into a black low-volume 384-well microtiter plate (Greiner Bio-One, Frickenhausen, Germany). 2 μL of a solution of c-Met in assay buffer [25 mM Hepes/NaOH, pH 7.5; 5 mM MgCl2; 5 mM MnCl2; 2 mM dithiothreitol; 0.1% (v/v) Tween 20 (Sigma); 0.1% (w/v) bovine serum albumin] are added, and the mixture is incubated for 15 min at 22° C. to allow pre-binding of the test compound to the enzyme before the start of the kinase reaction. Then, the kinase reaction is started by the addition of 3 μL of a solution of adenosine triphosphate (ATP, 16.7 μM; final concentration in the 5 μL assay volume is 10 μM) and substrate (2.27 μg/mL, final concentration in the 5 μL assay volume is 1.36 μg/mL 30 nM) in assay buffer, and the resulting mixture is incubated for a reaction time of 30 min at 22° C. The concentration of c-Met in the assay is adjusted depending on the activity of the enzyme lot and is appropriately chosen to have the assay in the linear range; typical enzyme concentrations are in the range of about 0.03 nM (final concentration in the 5 μL assay volume). The reaction is stopped by the addition of 5 μL of a solution of HTRF detection reagents [40 nM streptavidine-X Lent and 2.4 nM PT66-Eu-chelate, an europium-chelate labelled anti-phosphotyrosine antibody (Perkin-Elmer)] in an aqueous EDTA solution [100 mM EDTA, 0.2% (w/v) bovine serum albumin in 50 mM HEPES/NaOH, pH 7.5]. The resulting mixture is incubated for 1 h at 22° C. to allow the binding of the biotinylated phosphorylated peptide to the streptavidine-XLent and the PT66-Eu-chelate. Subsequently, the amount of phosphorylated substrate is evaluated by measurement of the resonance energy transfer from the PT66-Eu-chelate to the streptavidine-XLent. Therefore, the fluorescence emissions at 620 nm and 665 nm after excitation at 350 nm are measured in an HTRF reader, e.g. Rubystar (BMG Lab-technologies, Offenburg, Germany) or Viewlux (Perkin-Elmer). The ratio of the emissions at 665 nm and at 622 nm is taken as the measure for the amount of phosphorylated substrate. |
| Affinity data for this assay | |
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