Assay Method Information

Assay Name:  Bcl-2 Competition Binding (Fluorescence Polarization) Assay
Description:  The fluorescence-labeled 23 amino acid peptide BH3 was purchased from CalBiochem (NLWAAQRYGRELRRMSDKFVD, SEQ ID NO: 1). An unbound Fluorescein labeled BH3 peptide emits random light with respect to the plane of polarization plane of excited light, resulting in a lower polarization degree (mP) value. When the peptide is bound to Bcl-2, the complex tumble slower and the emitted light can have a higher level of polarization, resulting in a higher mP value. This binding assay was performed in 96-well plate and with each assay contained 15 and 30 nM of labeled peptide and purified Bcl-2 protein (purchased from R&D Systems, Inc). The assay buffer contained 20 mM Hepes (pH 7.0), 50 mM KCl, 5 mM MgCl2, 20 mM Na2MoO4, 0.1 mg/ml Bovine Gamma Globulin and 0.01% NP40. Compounds were diluted in DMSO and added to the final assay with concentration range from 20 uM to 2 nM. The polarization degree (mP) value was determined by BioTek Synergy II with background subtraction after 3 hours of incubation at room temperature. IC50 was calculated using Prism software with sigmoidal dose-response curve fitting. ABT-737 was used as reference compound. Such assays, carried out with a range of doses of test compounds, allow the determination of an approximate IC50 value. Although the inhibitory properties of the compounds of the present invention vary with structural change as expected, the activity generally exhibited by these agents is in the range of IC50=0.1-1000 nM.
Affinity data for this assay
 

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