common allosteric binding site of muscarinic M2 receptors, the orthosteric site of which was liganded with the N-methylscolopamine. The phthalimido substituted hexane-bisammonium compoundW84 served as a starting point. Previous molecular modelling studies revealed two positive charges and two aromatic imides in a sandwich-like arrangement to be essential for a high allosteric potency. A three-dimensional
the orthosteric receptor site in equilibrium binding and dissociation experiments. 1,8-Naphthalimido residues conferred an up to 100-fold gain in affinity leading into the low nanomolar range, while the inhibition of NMS binding was maintained. Additional propyl chain methylation was accompanied by an allosteric elevation of orthosteric ligand binding. In general, the gain in allosteric activity achieved