| Assay Method Information | |
| | Binding Assay |
| Description: | The binding assays were performed by testing the ability of the new compounds to displace the radiolabeled synthetic non-selective cannabinoid agonist [3H]CP55940 (168 Ci/mmol; PerkinElmer) from the human CB1 (hCB1) or human CB2 (hCB2) receptors on membranes derived from stably transfected HEK-293 cells (PerkinElmer). Membranes were diluted in assay buffer (50 mM Tris-HCl, 1 mM EDTA, 1 mM MgCl2, 1 mg/ml BSA, pH=7.4). The amount of membrane was determined for each batch of membranes according to protein binding assay. The minimum amount of membrane that gave 50% specific binding was used for the binding assay. In most assays, binding was tested using 8 μg and 4 μg protein of hCB1 and hCB2 membranes, respectively. The tested compounds were dissolved in DMSO and diluted in assay buffer to a final concentration of 0.1% solvent. Total binding of [3H]CP55940 was evaluated with 1.5 nM to hCB1 and with 0.5 nM to hCB2, according to Kd affinity of [3H]CP55940 for the respective membranes. The ability of the tested compounds to displace [3H]CP55940 was evaluated first at a single concentration point of 100 nM for binding toward hCB2 or hCB1. In certain cases, the displacement was tested at compound concentrations ranging from 0.03 nM to 10 μM. Non-specific binding was measured by the addition of 1 μM of unlabelled CP55940 to the tubes. Binding assays were performed in triplicate in a total volume of 500 μl for 60 minutes at 30° C., in a shaking bath. Free and bound radioligands were separated by rapid filtration through GF/C filter plates (PerkinElmer) that had been presoaked with 0.1% Polyethylenimine (Sigma). Filters were shaken for 1 hour in 7 ml scintillation fluid (PerkinElmer) and radioactivity was determined by liquid scintillation counter (Wallac; PerkinElmer). |
| Affinity data for this assay | |
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