title: Radiolabeled Dibenzodiazepinone-Type Antagonists Give Evidence of Dualsteric Binding at the M2Muscarinic Acetylcholine Receptor.
abstract: The dualsteric ligand approach, aiming at ligands with improved subtype selectivity, has been increasingly applied to muscarinic receptors (MRs). In this article, we present the synthesis and characterization of a M2R subtype-preferring radiolabeled dibenzodiazepinone-type antagonist ([3H]UNSW-MK259, [3H]19) and its homodimeric analogue [3H]UR-AP060 ([3H]33). Saturation binding studies at the M2R, using the orthosteric antagonist atropine to determine unspecific binding, proved that the monomeric and the dimeric compound bind to the orthosteric binding site (apparent Kd: 0.87 and 0.31 nM, respectively). Various binding studies with [3H]19 and [3H]33 at the M2R, for instance, saturation binding experiments in the presence of the allosteric MR modulators W84 (8) or LY2119620 (9) (Schild-like analysis) suggested a competitive mechanism between the allosteric modulator and the dibenzodiazepinone derivatives, and thus a dualsteric binding mode of both 19 and 33. This was consistent with the results of M2R MD simulations (≥2 μs) performed with 19 and 33.
authors.affiliation: Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg , Universitätsstrasse 31, D-93053 Regensburg, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Pegoli
authors.affiliation: Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg , Universitätsstrasse 31, D-93053 Regensburg, Germany.
authors.forename: Xueke
authors.initials: X
authors.lastname: She
authors.affiliation: Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg , Universitätsstrasse 31, D-93053 Regensburg, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Wifling
authors.affiliation: Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University , Schuhstrasse 19, D-91052 Erlangen, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Hübner
authors.affiliation: Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg , Universitätsstrasse 31, D-93053 Regensburg, Germany.
authors.forename: Günther
authors.initials: G
authors.lastname: Bernhardt
authors.affiliation: Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University , Schuhstrasse 19, D-91052 Erlangen, Germany.
authors.forename: Peter
authors.identifier: 0000-0002-4127-197X
authors.initials: P
authors.lastname: Gmeiner
authors.affiliation: Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg , Universitätsstrasse 31, D-93053 Regensburg, Germany.
authors.forename: Max
authors.identifier: 0000-0002-8095-8627
authors.initials: M
authors.lastname: Keller
mesh_terms: D001570:Benzodiazepinones / Q000378:metabolism*; D001665:Binding Sites; D056004:Molecular Dynamics Simulation; D018727:Muscarinic Antagonists / Q000494:pharmacology*; D011868:Radioisotopes / Q000737:chemistry*; D043585:Receptor, Muscarinic M2 / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D001570:Benzodiazepinones; D018727:Muscarinic Antagonists; D011868:Radioisotopes; D043585:Receptor, Muscarinic M2