Assay Method Information

Assay Name:  Fluorescence Polarization (FP) Assay
Description:  Measuring compound ligand binding to CRBN-DDB1 was carried out using an established sensitive and quantitative in vitro fluorescence polarization (FP) based binding assay. (See, I. J. Enyedy et al, J. Med. Chem., 44: 313-4324 [2001]). Compounds were dispensed from serially diluted DMSO stock into black 384-well compatible fluorescence polarization plates using an Echo acoustic dispenser. Compound binding to CRBN-DDB1 was measured by displacement of either a (−)-Thalidomide-Alexa Fluor or Pomalidomide-fluorescein conjugated probe dye. A 20 μL mixture containing 400 nM CRBN-DDB 1 and 5 nM probe dye in 50 mM Hepes, pH 7.4, 200 mM NaCl, 1% DMSO and 0.1% pluronic acid-127 acid was added to wells containing compound and incubated at room temperature for 60 min. Matching control wells excluding CRBN-DDB1 were used to correct for background fluorescence. Plates were read on an Envision plate reader with appropriate FP filter sets. The corrected S (perpendicular) and P (parallel) values were used to calculate fluorescence polarization (FP) with the following equation: FP=1000*(S−G*P)/(S+G*P). The fractional amount of bound probe (FB) to CRBN-DDB1 as a function of compound concentration was fitted according to Wang; FEBS Letters 360, (1995), 111-114 to obtain fits for parameter offsets and binding constant (KA) of competitor compound.
Affinity data for this assay
 

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