Assay Method Information

Assay Name:  BTK Enzyme Activity Testing
Description:  In vitro activity of BTK is measured by detecting ADP produced in a kinase reaction with an ADP-Glo kinase assay kit from Promega Company. In the kinase assay, the kinase consumes ATP to phosphorylate the substrate, while producing ADP. ADP-Glo reagent then terminates the kinase reaction and completely consumes the remaining ATP. Finally, a kinase detection reagent is added to convert generated ADP into new ATP. Luciferase in the detection reagent is capable of catalyzing fluorescein with the participation of ATP and O2 to produce oxidized fluorescein, AMP, and generate light quantum, thereby converting a chemical signal into an optical signal (Luminecence). The intensity of optical signal is positively correlated with the production of ADP in the kinase reaction, so that the activity of kinase BTK can be thereby quantitatively determined.All assays are conducted at a constant temperature of 23° C., using a Corning 3674 Type white 384-well plate; the BTK kinase (full length with His-Tag) is expressed and purified internally by the company; the substrate of kinase is polypeptide (4:1 Glu,Tyr) (from SignalChem) and ATP (from Sigma); and a microplate reader EnVision (Perkin Elmer) is used for reading an optical signal. The assay buffer includes 40 mM Tris-HCl (pH 7.5), 10 mM MgCl2 (Sigma), 2 mM MnCl2 (Sigma), 0.05 mM DTT (Sigma), and 0.01% BSA (Sigma); the BTK kinase is diluted with the assay buffer to a concentration of 1.6 ng/uL as a kinase reaction solution; and the substrate reaction solution comprises 0.2 mg/mL polypeptide substrate and 50 uM ATP.Compound's IC50 is calculated from 10 concentration points by the following method. The compound is dissolved and diluted in 100% DMSO to a concentration of 1 mM, followed by a serial 3× dilution with DMSO to a minimum concentration of 0.05 uM. Each concentration stock is further diluted 40× with the assay buffer. To a 384-well assay plate are added 1 uL of a series of compound solutions and 2 uL of the kinase reaction solution, followed by mixing homogeneously, and incubating in the dark at room temperature. After in the dark for 30 min, 2 uL of the substrate reaction solution is added to allowed the total reaction volume to 5 uL. The reaction mixture is incubated in the dark at room temperature in the dark for another 60 min. An equal volume of 5 uL ADP-Glo reagent is then added to terminate the reaction. The resulting mixture is homogeneously mixed, and stands at room temperature for 40 min. Finally, 10 uL of the kinase detection reagent is added, stands at room temperature for 30 min, and then a value is read on Envision.
Affinity data for this assay
 

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