| Assay Method Information | |
| | Receptor Binding of PEG-Nalbuphine Conjugates |
| Description: | Briefly, the receptor binding affinity of the nalbuphine and PEG-nalbuphine conjugates was measured using radioligand binding assays in CHO cells that heterologously express the recombinant human mu, delta or the kappa opioid receptor. Cells were plated in 24 well plates at a density of 0.2-0.3*106 cells/well and washed with assay buffer containing 50 mM Tris.HCl and 5 mM MgCl2 (pH 7.4). Competition binding assays were conducted in whole cells incubated with increasing concentrations of test compounds in the presence of appropriate concentration of radioligand. 0.5 nM 3H Naloxone, 0.5 nM 3H Diprenorphine and 0.5 nM 3H DPDPE were used as the competing radioligands for mu, kappa and delta receptors respectively. Incubations were carried out for two hours at room temperature using triplicate wells at each concentration. At the end of the incubation, cells were washed with 50 mM Tris HCl (pH 8.0), solubilized with NaOH and bound radioactivity was measured using a scintillation counter.Specific binding is determined by subtraction of the cpm bound in the presence of 50-100× excess of cold ligand. Binding data assays were analyzed using GraphPad Prism 4.0 and IC50 is generated by non-linear regression from dose-response curves. Ki values were calculated using the Cheng Prusoff equation using the Kd values from saturation isotherms as follows: Ki=IC50/(1+[Ligand]/Kd). |
| Affinity data for this assay | |
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