| Assay Method Information | |
| | Biological Assay for TBK1 and IKKs |
| Description: | Enzymatic activity of IKKε and TBK1 was measured using a homogeneous time resolved fluorescence resonance energy transfer (TR-FRET) assay that monitors enzyme dependent phosphorylation of a biotinylated serine/threonine peptide substrate. An increase in the amount of phopshorylated peptide results in an increase in TR-FRET signal. TBK1 and IKKs were expressed and purified as full length recombinant proteins. Detection reagents for the assay were purchased from Cisbio. TBK1 and IKKε enzymes were assayed under initial rate conditions in the presence of 2× Km ATP (40-80 μM) and 1 μM peptide, hepes (pH 7), 0.1 mM orthovanadate, 0.02% NaN3, 0.01% BSA, 10 mM MgCl2, 0.01% (v/v) tritonX, 1 mM dithiothreitol, 0.5% (v/v) DMSO at the following concentrations for each enzyme: TBK1 at 2.5 nM and IKKε at 0.3 nM. After an assay reaction time of 240 minutes at 25° C., reactions were terminated with EDTA.Amount of phosphorylated peptide was determined by the addition of 125 nM streptavidin XL665 and europium cryptate labeled anti-phospho monoclonal antibody and the resulting TR-FRET signal was recorded on an Envision plate reader (Ex: 340 nm; Em: 615/665 nm; 100 μs delay and 200 μs read window). Data was normalized based on a positive (1 μM Staurosporine) and negative (DMSO) controls and IC50 values calculated from the fit of the dose-response curves to a four-parameter equation. All IC50 values represent geometric mean values of a minimum of four determinations. |
| Affinity data for this assay | |
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