Fluorescent derivatives of AC-42 to probe bitopic orthosteric/allosteric binding mechanisms on muscarinic M1 receptors.

Article Details

Citation

Daval SB, Valant C, Bonnet D, Kellenberger E, Hibert M, Galzi JL, Ilien B

Fluorescent derivatives of AC-42 to probe bitopic orthosteric/allosteric binding mechanisms on muscarinic M1 receptors.

J Med Chem. 2012 Mar 8;55(5):2125-43. doi: 10.1021/jm201348t. Epub 2012 Feb 27.

PubMed ID
22329602 [ View in PubMed
]
Abstract

Two fluorescent derivatives of the M1 muscarinic selective agonist AC-42 were synthesized by coupling the lissamine rhodamine B fluorophore (in ortho and para positions) to AC42-NH(2). This precursor, prepared according to an original seven-step procedure, was included in the study together with the LRB fluorophore (alone or linked to an alkyl chain). All these compounds are antagonists, but examination of their ability to inhibit or modulate orthosteric [(3)H]NMS binding revealed that para-LRB-AC42 shared several properties with AC-42. Carefully designed experiments allowed para-LRB-AC42 to be used as a FRET tracer on EGFP-fused M1 receptors. Under equilibrium binding conditions, orthosteric ligands, AC-42, and the allosteric modulator gallamine behaved as competitors of para-LRB-AC42 binding whereas other allosteric compounds such as WIN 51,708 and N-desmethylclozapine were noncompetitive inhibitors. Finally, molecular modeling studies focused on putative orthosteric/allosteric bitopic poses for AC-42 and para-LRB-AC42 in a 3D model of the human M1 receptor.

DrugBank Data that Cites this Article

Binding Properties
DrugTargetPropertyMeasurementpHTemperature (°C)
CarbamoylcholineMuscarinic acetylcholine receptor M1EC 50 (nM)250N/AN/ADetails
CarbamoylcholineMuscarinic acetylcholine receptor M3EC 50 (nM)15000N/AN/ADetails
Methscopolamine bromideMuscarinic acetylcholine receptor M1Ki (nM)0.17N/AN/ADetails
Methscopolamine bromideMuscarinic acetylcholine receptor M1Ki (nM)0.0955N/AN/ADetails