Assay Method Information

Assay Name:  JAK Family Caliper Enzyme Assay
Description:  Compounds of the invention were evaluated by in vitro methods to determine their respective ability to inhibit the JAK kinases (TYK2, JAK1, JAK2, JAK3). Inhibitory activity was determined by using a microfluidic assay (LabChip 3000 mobility shift technology, Caliper Life Science) to monitor phosphorylation of a synthetic peptide by the recombinant human kinase domain of each of the four members of the JAK family, JAK1, JAK2, JAK3 and TYK2. Reaction mixtures contained 1 μM of a fluorescently labeled synthetic peptide, a concentration less than the apparent Km, and 1 mM ATP. Compounds in DMSO solution were added to a 384-well plate. Reaction mixtures contained 10 mM HEPES, pH 7.4, 10 mM MgCl2, 0.01% BSA, 0.0005% Tween 20 , 1 mM ATP and 1 μM peptide substrate. The JAK1 and TYK2 assays contained 1 μM of the IRStide peptide (5FAM-KKSRGDYMTMQID) and the JAK2 and JAK3 assays contained 1 μM of the JAKtide peptide (FITC-KGGEEEEYFELVKK). The assays were initiated by the addition of 20 nM JAK1, 1 nM JAK2, 1 nM JAK or 1 nM TYK2 enzyme and were incubated at room temperature for three hours for JAK1, 60 minutes for JAK2, 75 minutes for JAK3 or 135 minutes for TYK2. Enzyme concentrations and incubation times were optimized for each new enzyme preps and were modified slightly over time to ensure 20% to 30% phosphorylation. The assays were stopped with 15 μL of 180 mM HEPES, pH 7.4, 20 mM EDTA, and 0.2% Coating Reagent 3. The assay plates were placed on a Caliper Life Science LC3000 instrument, and each well was sampled using appropriate separation conditions to measure the unphosphorylated and phosphorylated peptide.
Affinity data for this assay
 

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