| Assay Method Information | |
| | Inhibition of Mcl-1 by fluorescence polarization (FP) assay |
| Description: | The relative binding potency of representative Compounds of the Disclosure was determined by a fluorescence polarization (FP) assay. The method used a fluorescein labelled peptide (FAM-Bid) which binds to the Mcl-1 protein leading to an increased anisotropy measured in milli-polarization (mP) values using a plate reader. A 21-residue Bid BH3 peptide (residues 79-99) [Swiss-Prot: P55957] was labeled at the N-terminus with 6-carboxyfluorescein succinimidyl ester (FAM) to give FAM-Bid as a tracer in the FP competitive binding assay. Tag-free Mcl-1 protein (residues 171-323) was used in the FP assay (Mady et al,Scientific Reports 8: 10210-10210 (2018); Yang et al, ACS Med. Chem. Lett. 3:308-312 (2012)). The addition of compounds which binds competitively to the same site as the labelled peptide will result in a greater proportion of unbound peptide in the system indicated by a decreased mP value. A 10-points serial dilution of each compound was prepared in DMSO and 5 μL solution was transferred into flat bottomed, 96-well back plate (final DMSO concentration 5%). 120 μL of Buffer (PBS, 0.01% BGG (Sigma Cat. #SRE0011), 0.01% Triton X-100), containing the Fluorescein labelled peptide (Final concentration 2 nM) and Mcl-1 protein (final concentration 20 nM) was then added. Assay plates were incubated 30 mins at room temperature with gentle shaking before FP was measured on a Biotek Synergy 1MF reader (Ex. 485 nm, Em. 528 nm, Cut off 510 nm) and mP calculated. The binding of increasing doses of test compounds was expressed as a percentage reduction in mP compared to a window established between 5% DMSO only and 100% inhibition controls (no Mcl-1 protein). 10-points dose response curves were plotted with GraphPad software using Sigmoidal Dose-Response Model and the IC50 values were determined by nonlinear regression fitting of the competition curves. |
| Affinity data for this assay | |
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