Assay Method Information

Assay Name:  JAK1 and JAK3 Enzyme Activity Assays
Description:  The activity of JAK3 (a.a. 781-1124, ThermoFisher) was quantified by measuring the phosphorylation of SRCtide (FAM-GEEPLYWSFPAKKK-NH2). Kinase reactions were run in a 384-well Greiner plate with 2% final DMSO concentration under the buffer conditions of 20 mM HEPES, pH 7.5, 10 mM MgCl2, 0.01% BSA, and 0.0005% Tween-20. The kinase reaction components were 2.5 nM JAK3, 1 μM SRCtide peptide and 1 uM ATP. Examples were tested in dose-response starting at 2 μM (11 concentrations, 3-fold serial dilution, duplicate reactions). The reactions were incubated at room temperature for 40 minutes, then stopped by adding a 1:1 volume of 30 mM EDTA in 20 mM HEPES, pH 7.5 (15 mM EDTA final). After the reaction was stopped, the phosphorylated and unphosphorylated peptides were separated and quantified using a Caliper LC3000/EZ-Reader system and HTS Well Analyzer Software (Caliper, A PerkinElmer Company, Hopkinton, Mass.). GraFit (Erithacus Software Ltd., Horley, U.K.) was used to calculate inhibitor potency by fitting dose-response data to the 4-parameter logistical IC50 equation.The inhibitory potency of candidate compounds of JAK1 done at Thermo Fisher Scientific in their Selectscreen using a Z-lyte assay. The 2×JAK1/Tyr 06 mixture is prepared in 50 mM HEPES pH 6.5, 0.01% BRIJ-35, 10 mM MgCl2, 1 mM EGTA, 0.02% NaN3. The final 10 μL of the Kinase Reaction consists of 21.2-91.5 ng JAK1 and 2 μM Tyr 06 in 50 mM HEPES pH 7.0, 0.01% BRIJ-35, 10 mM MgCl2, 1 mM EGTA, 0.01% NaN3. After the 1 hour Kinase Reaction incubation, 5 μL of a 1:128 dilution of Development Reagent is added.Background signal is defined in the absence of enzyme and uninhibited signal is defined in the presence of vehicle (2% DMSO) alone. Compounds were evaluated in an 11 point dose-response ranging from 20 mM to 0.34 nM. IC50 values of compounds are determined using a 4 parameter logistical fit of emission ratio as a function of the concentration of compound.
Affinity data for this assay
 

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