title: Modeling subtype-selective agonists binding with alpha4beta2 and alpha7 nicotinic acetylcholine receptors: effects of local binding and long-range electrostatic interactions.
abstract: The subtype-selective binding of 14 representative agonists with alpha4beta2 and alpha7 nicotinic acetylcholine receptors (nAChRs) has been studied by performing homology modeling, molecular docking, geometry optimizations, and microscopic and phenomenological binding free energy calculations. All of the computational results demonstrate that the subtype selectivity of the agonists binding with alpha4beta2 and alpha7 7 nAChRs is affected by both local binding and long-range electrostatic interactions between the receptors and the protonated structures of the agonists. The effects of the long-range electrostatic interactions are mainly due to the distinct difference in the net charge of the ligand-binding domain between the two nAChR subtypes. For the alpha4beta2-selective agonists examined, the microscopic binding modes with the alpha4beta2 nAChR are very similar to the corresponding modes with the alpha7 nAChR, and therefore, the subtype selectivity of these agonists binding with alpha4beta2 and alpha7 nAChRs is dominated by the long-range electrostatic interactions. For the alpha7-selective agonists, their microscopic binding modes with the alpha7 nAChR are remarkably different from those with the alpha4beta2 nAChR so that the local binding (including the hydrogen bonding and cation-pi interactions) with the alpha7 nAChR is much stronger than that with the alpha4beta2 nAChR. The calculated phenomenological binding free energies are in good agreement with available experimental data for the relative binding free energies concerning the subtype selectivity of agonists binding with the two different nAChR subtypes. The fundamental insights obtained in the present study should be valuable for future rational design of potential therapeutic agents targeted to specific nAChR subtypes.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 725 Rose Street, Lexington, KY 40536, USA.
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Huang
authors.forename: Fang
authors.initials: F
authors.lastname: Zheng
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.forename: Peter A
authors.initials: PA
authors.lastname: Crooks
authors.forename: Linda P
authors.initials: LP
authors.lastname: Dwoskin
authors.forename: Chang-Guo
authors.initials: CG
authors.lastname: Zhan
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000187:drug effects; D003198:Computer Simulation; D006801:Humans; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018722:Nicotinic Agonists / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D051381:Rats; D011978:Receptors, Nicotinic / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity; D013329:Structure-Activity Relationship; D064569:alpha7 Nicotinic Acetylcholine Receptor
chemical_list: C579167:Chrna7 protein, human; C579165:Chrna7 protein, rat; D008024:Ligands; D018722:Nicotinic Agonists; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor; C403531:nicotinic receptor alpha4beta2