Affinity labeling of muscarinic receptors in rat cerebral cortex with a photolabile antagonist

摘要: Highly potent photoaffinity probes for muscarinic binding sites were prepared by the incorporation of an azido group into benzilic acid moiety in two compound, 3-quinuclidinyl benzilate (3QNB) and N-methyl-4-piperidyl (4NMPB). Inactivation rat cortex depends on formation a reversible complex with azides prior to their photolytic conversion highly reactive nitrenes. During photolysis, radiolabeled azido-4NMPB interacted specifically high affinity (Kd = 1.06 nM) receptors, ligand could be covalently incorporated macromolecule about 86,000 Mr, presumably receptor. The was almost stoichiometric when compared determination receptor density ligands. Atropine (10 microM) afforded specific protection (greater than 83%) against inactivation azido-[3H]4NMPB. This compound other ligands described here (i.e., amino-4NMPB, amino-3QNB, azido-3QNB) represent powerful potential biochemical isolation characterization receptors.