| Assay Method Information | |
| | Biochemical Assay |
| Description: | For the SAR (structure-activity relationship) and compound screening, LanthaScreen TR-FRET (Time-Resolved fluorescence energy transfer) assay was employed using the phospho-tyrosine specific Terbium (Tb)-labeled antibody with a fluorescein labeled poly-GT (glutamate-tyrosine) as a substrate. Upon excitation at 340 nm by UV, the energy from Tb donor of the antibody is transferred to the fluorescein of the phosphorylated poly GT substrate, and fluorescein emits light at 520 nm. The ratio between the intensity of primary emission at 495 nm and that of secondary emission at 520 nm was used to quantify the level of kinase activity. The recombinant proteins of human c-MER and AXL catalytic domains, Fluorescein-labeled poly-GT substrate, Tb-labeled anti-phosphorylated tyrosine antibodies, the kinase assay buffer, and 0.5M EDTA solution were purchased (Life technologies, USA). The TR-FRET assays were carried out in the white low volume 384-well plate (Corning, USA). To measure the compound mediated inhibition of kinase activity, the recombinant kinases were pre-incubated with test compounds for 20 minutes prior to the addition of 200 nM fluorescein labeled poly-GT substrates and 10 uM ATP, and then the reaction was carried out for 1 hour at room temperature. 10 mM EDTA was added to terminate the enzyme reaction, and the level of phosphorylation of poly-GT substrate was determined following 30 min incubation with 2 nM Tb-labeled antibody. The fluorescence intensity was measured with Envision plate reader (PerkinElmer, USA). |
| Affinity data for this assay | |
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