Assay Method Information | |
| Fluorescence Polarization Assay |
Description: | Bcl-2 and Bcl-xL Inhibition: Fluorescein labeled BIM (81-106), BAK (72-87), and BID (79-99) peptides, named as Flu-BIM, Flu-BAK, and Flu-BID, respectively, were used as the fluorescent probes in FP assays for Bcl-2, Bcl-xL, and Md-1, respectively. By monitoring the total fluorescence polarization values of mixtures composed of fluorescent probes at fixed concentrations and proteins with increasing concentrations up to the full saturation, the Kd values of Flu-BIM to Bcl-2, Flu-BAK to Bcl-xL and Flu-BID to Md-1 were determined to be 0.55±0.15, 4.4±0.8 and 6.9±0.9 nM, respectively. Fluorescence polarization values were measured using the Infinite M-1000 plate reader (Tecan U.S., Research Triangle Park, N.C.) in Microfluor 1 96-well, black, round-bottom plates (Thermo Scientific). To each well, 1 nM of Flu-BIM, or 2 nM of Flu-BAK or 2 nM of Flu-BID and increasing concentrations of Bcl-2, or Bcl-xL, or Md-1 were added to a final volume of 125 μl in the assay buffer (100 mM potassium phosphate, pH 7.5, 100 μg/ml bovine γ-globulin, 0.02% sodium azide, Invitrogen, with 0.01% Triton X-100 and 4% DMSO). Plates were mixed and incubated at room temperature for 1 hour with gentle shaking to assure equilibrium. The polarization values in millipolarization units (mP) were measured at an excitation wavelength of 485 nm and an emission wavelength of 530 nm. |
Affinity data for this assay | |
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