Geometry of muscarinic agonists

In order to account for a common geometric character of the skeleton of known muscarinic agonist molecules in the drug-receptor interaction, common key atoms, terminal methyl carbon, two oxygen, and ammonium nitrogen atoms were remarked which were shown by computer calculation to be concentrated at definite points in space and to be arranged nearly in a plane. Comparison of overlapped patterns of potent agonists and weak-acting or inactive analogues drew a conclusion that the complemental receptor site have a relatively flat shape.