Assay Method Information

Assay Name:  Btk In Vitro Inhibitory Assay
Description:  Human Btk kinase (Genbank accession # NP_000052) was purified from insect cells as a full-length construct containing a N-terminal 6×-His tag. Btk kinase activity was determined using a radiometric filter binding assay. Measurements are performed in a low μL reaction volume 384-well assay plates. BTK enzyme (8 nM final in reaction), inhibitor (at requested doses), and 0.2 mg/mL peptide substrate (Poly-Glu-Tyr, 4:1 ratio) are incubated in a reaction buffer composed of 20 mM Hepes (pH 7.5), 10 mM MgCl2, 1 mM EGTA, 0.02% Brij35, 0.02 mg/ml BSA, 0.1 mM Na3VO4, 2 mM DTT, 1% DMSO for 15 min. followed by addition of 1 μM ATP to start the assay. Kinase reactions are carried out for 120 min. at room temperature. The reaction was stopped by spotting of reaction sample onto P81 cationic exchange paper (Whatman). Unbound phosphate was removed by extensive washing of filters in 0.75% Phosphoric acid. After subtraction of background derived from control reactions containing inactive enzyme (via addition of saturating EDTA), kinase activity data for each dose of compound tested was expressed as the percent of remaining kinase activity in test samples compared to vehicle (dimethyl sulfoxide) reactions.
Affinity data for this assay
 

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