title: Molecular docking study of the binding of aminopyridines within the K+ channel.
abstract: We present a molecular docking study aimed to identify the binding site of protonated aminopyridines for the blocking of voltage dependent K(+) channels. Several active aminopyridines are considered: 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, 3,4-diaminopyridine, and 4-aminoquinoleine. We apply the AutoDock force field with a lamarckian genetic algorithm, using atomic charges for the ligands derived from the electrostatic potential obtained at the B3LYP/cc-pVDZ level. We find a zone in the alpha-subunit of the K(+) channel bearing common binding sites. This zone corresponds to five amino acids comprised between residuals Thr107 and Ala111, in the KcsA K(+) channel (1J95 pdb structure). The 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, and 3,4-diaminopyridine bind to the carboxylic oxygens of Thr107 and Ala111. In all cases aminopyridines are perpendicular to the axis of the pore. 4-aminoquinoleine binds to the carboxylic oxygen of Ala111. Due to its large size, the molecular plane is parallel to the axis of the pore. The charge distributions and the structures of the binding complexes suggest that the interaction is driven by formation of several hydrogen bonds. We find 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, and 3,4-diaminopyridine with similar binding energy. Considering the standard error of the estimate of the AutoDock force field, this energy should lie, as a rough estimation, in the interval 3-7 kcal mol(-1). On the other hand, 4-aminoquinoleine seems to have a smaller binding energy.
authors.affiliation: Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Lab. de Química Teórica, Centro de Investigación, Benemérita Universidad Autónoma de Puebla, San Claudio y 14 Sur, Ciudad Universitaria, Puebla, Puebla, Mexico.
authors.forename: Norma Angélica
authors.initials: NA
authors.lastname: Caballero
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Meléndez
authors.forename: Alfonso
authors.initials: A
authors.lastname: Niño
authors.forename: Camelia
authors.initials: C
authors.lastname: Muñoz-Caro
mesh_terms: D000631:Aminopyridines / Q000737:chemistry* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D006863:Hydrogen-Ion Concentration; D015221:Potassium Channels / Q000737:chemistry / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D021381:Protein Transport
chemical_list: D000631:Aminopyridines; D001426:Bacterial Proteins; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; C107790:prokaryotic potassium channel