Assay Method Information

Assay Name:  TR-FRET Kinase Assay
Description:  The ability of compounds to inhibit ASK1 kinase activity was determined using a time resolved fluorescence resonance energy transfer [TR-FRET] assay utilizing biotinylated myelin basic protein [biotin-MBP] as the protein substrate. A Beckman Biomek FX liquid handling robot was utilized to spot 2 μL/well of compounds in 2.44% aqueous DMSO into low volume 384-well polypropylene plates [Nune, #267460] to give a final concentration of between 100 μM and 0.5 nM compound in the kinase assay. A Decrac Fluidics Equator was used to dispense 3 μL/well of 0.667 ng/μL [Upstate Biotechnologies, #14-606, or the equivalent protein prepared in-house] and 0.1665 ng/mL biotin-MBP [Upstate Biotechnologies, #13-111] in buffer (85 mM MOPS, pH 7.0, 8.5 mM Mg-acetate, 5% glycerol, 0.085% NP-40, 1.7 mM DTT and 1.7 mg/mL BSA) into the plates containing the spotted compounds. The enzyme was allowed to pre-incubate with compound for 20 minutes prior to initiating the kinase reaction with the addition of 5 μL/well 300 μM ATP in buffer (50 mM MOPS, pH 7.0, 5 mM Mg-acetate, 1 mM DTT, 5% DMSO) using the Decrac Fluidics Equator. The kinase reactions were allowed to proceed for 20 minutes at ambient temperature and were subsequently stopped with the addition of 5 μL/well 25 mM EDTA using the Deerac Fluidics Equator. The Biomek FX was then used to transfer 1 μL/well of each completed kinase reaction to the wells of an OptiPlate-1536 white polystyrene plate [PerkinElmer, #6004299] that contained 5 μL/well detection reagents (1.11 nM Eu-W1024 labeled anti-phosphothreonine antibody [PerkinElmer, #AD0094] and 55.56 nM streptavidin allophycocyanin [PerkinElmer, #CR130-100] in 1×LANCE detection buffer [PerkinElmer, #CR97-100]). The TR-FRET signal was then read on a Perkin. Elmer Envision plate reader after incubating the plates at ambient temperature for 2 hours. The 100% inhibition positive control wells were generated by switching the order of addition of the EDTA and ATP solutions described above. These wells and 0% inhibition wells containing spots of 2.44% DMSO at the beginning of the assay were used in calculating the % inhibition for the test compounds.
Affinity data for this assay
 

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