Assay Method Information

Assay Name:  Receptor Binding Assay
Description:  Mu-Opioid Peptide (hMOP): The hMOP receptor binding assay was performed as homogeneous SPA-assay (scintillation proximity assay) using the assay buffer 50 mM TRIS-HCl (pH 7.4) supplemented with 0.052 mg/ml bovine serum albumin (Sigma-Aldrich Co. St. Louis. Mo.). The final assay volume (250 μl/well) included 1 nM of [N-allyl-2.3-3H]naloxone as ligand (PerkinElmer Life Sciences. Inc. Boston. Mass. USA). and either test compound in dilution series or 25 μM unlabelled naloxone for determination of unspecific binding. The test compound was diluted with 25% DMSO in H2O to yield a final 0.5% DMSO concentration. which also served as a respective vehicle control. The assay was started by adding wheat germ agglutinin coated SPA beads (GE Healthcare UK Ltd. Buckinghamshire. UK) which had been preloaded with hMOP receptor membranes (PerkinElmer Life Sciences. Inc. Boston. Mass. USA). After incubation for 90 minutes at RT and centrifugation for 20 minutes at 500 rpm the signal rate was measured by means of a 1450 Microbeta Trilux β-counter (PerkinElmer Life Sciences/Wallac. Turku. Finland). Half-maximal inhibitory concentration (IC50) values reflecting 50% displacement of [3H]naloxone-specific receptor binding were calculated by nonlinear regression analysis and Ki values were calculated by using the Cheng-Prusoff equation.
Affinity data for this assay
 

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