CHEMBL5732726

Homogeneous Time Resolved Fluorescence (HTRF) Assay: Assays were performed in black, flat-bottom, 384-well plates. The final assay volume was 50 μL prepared from additions of His-BIR3 (241-356, XIAP), fluorescein labeled SMAC peptide, and test compounds in assay buffer consisting of 20 mM Sodium Phosphate, 1 mM EDTA, 50 mM NaCl, 50 μg/ml BSA, and 0.05% PLURONIC® F68. The reaction was incubated at room temperature for 60 minutes, following which 10 μl of mouse anti-6× His-terbium labeled Fab (Medarex, Cis-bio) was added to the reaction (40 μl) for an additional 30 minute incubation. The HTRF signal, ratio of fluorescence intensities at emission wavelengths for fluorescein acceptor (520 nm) and terbium donor (615 nm), the 520/615 ratio, generated by the reaction was then measured on the Envision Plate Reader Inhibition data were calculated from the 520/615 ratio generated by the no protein control reactions for 100% inhibition and vehicle-only reactions for 0% inhibition. The final concentration of reagents in the assay was 1 nM N-His-BIR3(241-356, XIAP), 5 nM fluorescein labeled SMAC peptide, 0.25 nM anti-His-Tb-Fab, and 0.1% DMSO. Dose response curves were generated to determine the concentration required for inhibiting 50% of the HTRF signal (IC50). Compounds were dissolved at 3 mM in dimethylsulfoxide (DMSO) and evaluated at eleven serially diluted concentrations.