| Assay Method Information | |
| | Enzymatic Activity Assay |
| Description: | In the presence of SIK2 (resp. SIK1 or SIK3) and ATP the CHK-peptide (KKKVSRSGLYRSPSMPENLNRPR with C-terminal arginine amide modification) were phosphorylated at one of the four feasible serine's. Only one phosphorylation is observed under the assay conditions. 60 nl of each compound dilution series (12 point; dilution factor 3, generally 30 μM to 170 pM) in DMSO were transferred by acoustic dispensing to the assay plate and 30 min pre-incubated (ambient temperature) after the addition of 5 μl SIK1 (5 nM) resp. 5 μl SIK2 (0.5 nM) or 7 μl SIK3 (1.5 nM) in assay-buffer (12.5 mM HEPES (pH 7.0), 10 mM magnesium acetate, 0.005% BSA). 10 μM CHK-peptide solution and 5 μl 100 μM ATP for SIK1 & SIK2 resp. 3 μl for SIK3 in assay-buffer were added and incubated ambient for 45 min. 40 μl 0.125% formic acid in water were added to quench the reaction. RapidFire (RF) Mass Spectrometry was utilized for data generation as described below. The multiple charged species (3-5 charges) for the phosphorylated and non-phosphorylated form measured by MRM (Multiple Reaction Monitoring; API5000 or 6500+) or EIC (Extracted Ion Current; QToF) were summed up and the ratio calculated (sum phosphorylated species/sum all species) for data evaluation. Normalization was performed by Genedata software based on the non-inhibition control DMSO and the commercially available SIK inhibitor @ 1 μM YKL-05-099 (CAS number 1936529-65-5). |
| Affinity data for this assay | |
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