Assay Method Information

Assay Name:  Fluorescent Polarization Assay
Description:  Compound activity was monitored in a fluorescence polarization (FP) homogeneous assay using 1-[5-({2-[2-(2-{[2-(2,6-dioxopiperidin-3-yl)-1,3-dioxo-2,3-dihydro-1H-isoindol-4-yl]oxy}acetamido)ethoxy]ethyl}carbamoyl)pentyl]-3,3-dimethyl-2-[(1E,3E)-5-[(2E)-1,3,3-trimethyl-5-sulfo-2,3-dihydro-1H-indol-2-ylidene]penta-1,3-dien-1-yl]-3H-indol-1-ium-5-sulfonate as a fluorescent probe. Unless otherwise stated, all reagents were purchased from Sigma Aldrich. Enzymatic reactions were conducted in Perkin-Elmer Black 384 well ProxiPlate Plus (catalogue no. 6008269) in 10 sL total volume. Full length wild-type cereblon CRBN (80.0 nM, 10 sL) was incubated in assay buffer containing 20 mM HEPES (pH 8.0), 150 NaCl, 0.5 mM TCEP and 0.05% Tween 20 in the presence or absence of compound (300 nL). Inhibitors were stored as 10 mM DMSO stocks in an inert environment (low humidity, dark, low oxygen, room temperature) using the Storage Pod System. Compounds and DMSO were dispensed using the Echo E5XX (Labcyte Inc. USA) to give concentrations from 300 to 0.937 or 3000 to 9.3 nM in a 12 data point curve. Mutant YWAA CRBN (80.0 nM, 10 μL) which does not interact with the fluorescent probe was used as a negative control for the assay. Following incubation at room temperature for 30 min, the assay was initiated by dispensing the probe to a final concentration of 5 nM (2.5 nL of a 20 μM stock) using the Echo E5XX. FP was measured after a period of 12 hours using a Pherastar plate reader (BMG Labtech, Germany) exciting at 590 nm and measuring the amount of parallel and perpendicular light at 675 nm. The FP signal was subsequently normalized to the no-compound control (i.e., DMSO). Analysis and IC50 values were derived using Dotmatics (Dotmatics UK) software.
Affinity data for this assay
 

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