Interaction of noncompetitive inhibitors with an immobilized alpha3beta4 nicotinic acetylcholine receptor...

A large number of drug substances act as noncompetitive inhibitors (NCIs) of the nicotinic acetylcholine receptor (nAChR) by blocking the ion flux through the channel. An affinity chromatography technique has been developed for investigating the interactions between NCIs and the alpha3beta4 subtype of neuronal nAChR. The data obtained from the chromatographic study were used to construct QSAR models of the NCI-nAChR binding with both electronic and steric parameters observed as important descriptors. A molecular model of the transmembrane domain of the alpha3beta4 subtype of nAChR was constructed and used to simulate the docking of a series of NCIs. A key aspect of the model was the discovery of the cleft produced by the incorporation of the bulky phenylalanine moiety into the nonpolar section of the lumen by the beta4 subunit. Quantitatively, the results of docking simulations modeled the experimental affinity data better than QSAR results. The computational approach, combined with the modeling of NCI-nAChR interaction by affinity chromatography, can be used to predict possible toxicities and adverse interactions.