Rational design of partial agonists for the muscarinic m1 acetylcholine receptor

J Med Chem. 2015 Jan 22;58(2):560-76. doi: 10.1021/jm500860w. Epub 2014 Dec 19.

Abstract

Aiming to design partial agonists for a G-protein-coupled receptor based on dynamic ligand binding, we synthesized three different series of bipharmacophoric ligands composed of the orthosteric building blocks iperoxo and 1 linked to allosteric modulators (BQCA-derived compounds, BQCAd; TBPB-derived compound, TBPBd). Their interactions were studied with the human muscarinic acetylcholine M1-receptor (hM1) with respect to receptor binding and Gq-protein signaling. Results demonstrate that iperoxo/BQCAd (2, 3) and 1/BQCAd hybrids (4) act as M1 partial agonists, whereas 1/TBPBd hybrids (5) did not activate M1-receptors. Among the iperoxo/BQCAd-hybrids, spacer length in conjunction with the pattern of substitution tuned efficacy. Most interestingly, a model of dynamic ligand binding revealed that the spacer length of 2a and 3a controlled the probability of switch between the inactive purely allosteric and the active bitopic orthosteric/allosteric binding pose. In summary, dynamic ligand binding can be exploited in M1 receptors to design partial agonists with graded efficacy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CHO Cells
  • Cricetulus
  • Drug Design
  • Muscarinic Agonists / chemical synthesis*
  • Muscarinic Agonists / pharmacology
  • Receptor, Muscarinic M1 / agonists*
  • Structure-Activity Relationship

Substances

  • Muscarinic Agonists
  • Receptor, Muscarinic M1