| Assay Method Information | |
| | IMAP-FP Assay |
| Description: | Assay Method A: BTK enzymatic activity was determined in an IMAP-FP assay (Immobilized Metal ion Affinity-based fluorescence Polarization; Molecular Devices). Using this assay format, the potency (IC50) of each compound was determined from a 10 point (1:3 serial dilution, final compound concentration range in assay from 10 μM to 0.508 nM) titration curve using the following outlined procedure. To each well of a black Corning 384-well microplate (Corning Catalog #3575), 200 nL of compound (100 fold dilution in final assay volume of 20 μL) was dispensed, followed by the addition of 10 μL of 1× kinase buffer (10 mM Tris pH 7.2, 10 mM MgCl2, 0.01% Tween 20, 2 mM MnCl2, and 1 mM DTT) containing 0.16 ng/μL (2.1 nM) of BTK enzyme (recombinant protein from baculovirus-transfected Sf9 cells: full-length BTK, 6HIS-tag cleaved). Following a 60 minute compound & enzyme incubation, each reaction was initiated by the addition of 10 μL kinase buffer containing 100 nM Blk/Lyntide IMAP substrate peptide (5-carboxyfluorescein-EFPIYDFLPAKKK-NH2; Molecular Devices Catalog #R7188), and 10 μM ATP. The final reaction in each well of 20 μL consists of 1.05 nM hBTK, 50 nM Blk/Lyntide IMAP substrate, and 5 μM ATP. Phosphorylation reactions were allowed to proceed for 120 minutes and were immediately quenched by the addition of 40 μL IMAP detection beads resuspended in IMAP progressive binding buffer (beads were diluted 1:600 in 75% and 25% progressive binding buffer A and B, respectively; Molecular Devices). Plates were read on Packard microplate reader after 60 minutes binding equilibration using Fluorescence Polarization protocol. Specifically, fluorescence at 535 nm is measured using emission filters oriented both parallel and perpendicular to the polarized excitation filter. |
| Affinity data for this assay | |
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