| Assay Method Information | |
| | Biochemical Activities Determination for SIK1 Protein |
| Description: | Compounds were tested for inhibition of SIK1 kinase (aa1-303, Thermo Fisher) in assays based on the time-resolved fluorescence-resonance energy transfer (TR-FRET) methodology. The assays were carried out in 384-well low volume white plates in a reaction mixture containing SIK1 kinase, 110 uM ATP, 0.5 μM STK1 substrate and 0-10 μM compound in buffer containing 25 mM Tris, 0.01% Trition X-100, 0.5 mM EGTA, 5 mM MgCl2, 2.5 mM DTT, pH=7.5. The kinase was incubated with compounds for 60 minutes at room temperature and the reaction was initiated by the addition of ATP and STK1 substrate. After reaction at room temperature for 180 minutes, an equal volume of stop/detection solution was added according to the manufacture's instruction (CisBio Bioassays). The stop/detection solution contained STK Antibody-Cryptate and XL665-conjugated streptavidin (Cat: 62ST1PEC, Cisbio) in Detection Buffer (Cat: 62SDBRDF, Cisbio). Plates were sealed and incubated at room temperature for overnight, and the TR-FRET signals (ratio of fluorescence emission at 665 nm over emission at 620 nm with excitation at 337 nm wavelength) were recorded on a PHERAstar FS plate reader (BMG Labtech). Phosphorylation of STK1 substrate led to the binding of STK Antibody-Cryptate to the biotinylated SIK1 substrate, which places fluorescent donor (Eu3+ crypate) in close proximity to the accepter (Streptavidin-XL665), thus resulting in a high degree of fluorescence resonance energy transfer from the donor fluorophore (at 620 nm) to the acceptor fluorophore (at 665 nm). Inhibition of SIK1 kinase activity resulted in decrease of the TR-FRET signal. The IC50 for each compound was derived from fitting the data to the four-parameter logistic equation by Dotmatics. |
| Affinity data for this assay | |
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