title: Fluorescently labeled analogues of dofetilide as high-affinity fluorescence polarization ligands for the human ether-a-go-go-related gene (hERG) channel.
abstract: Novel fluorescent derivatives of dofetilide (1) have been synthesized. Analogues that feature a fluorescent probe attached through an aliphatic spacer to the central tertiary nitrogen of 1 have high affinity for the hERG channel, and affinity is dependent on both linker length and pendent dye. These variables have been optimized to generate Cy3B derivative 10e, which has hERG channel affinity equivalent to that of dofetilide. When bound to cell membranes expressing the hERG channel, 10e shows a robust increase in fluorescence polarization (FP) signal. In a FP binding assay using 10e as tracer ligand, Ki values for several known hERG channel blockers were measured and excellent agreement with the literature Ki values was observed over an affinity range of 2 nM to 3 muM. 10e blocks hERG channel current in electrophysiological patch clamp experiments, and computational docking experiments predict that the dofetilide core of 10e binds hERG channel in a conformation similar to that previously predicted for 1. These analogues enable high-throughput hERG channel binding assays that are rapid, economical, and predictive of test compounds' potential for prolonged QT liabilities.
authors.affiliation: Exploratory Medicinal Sciences and ADME Technology Group, Pfizer Global Research and Development, Groton, Connecticut 06340, USA.
authors.forename: David H
authors.initials: DH
authors.lastname: Singleton
authors.forename: Helen
authors.initials: H
authors.lastname: Boyd
authors.forename: Jill V
authors.initials: JV
authors.lastname: Steidl-Nichols
authors.forename: Matt
authors.initials: M
authors.lastname: Deacon
authors.forename: Marcel J de
authors.initials: MJ
authors.lastname: Groot
authors.forename: David
authors.initials: D
authors.lastname: Price
authors.forename: David O
authors.initials: DO
authors.lastname: Nettleton
authors.forename: Nora K
authors.initials: NK
authors.lastname: Wallace
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Troutman
authors.forename: Christine
authors.initials: C
authors.lastname: Williams
authors.forename: James G
authors.initials: JG
authors.lastname: Boyd
mesh_terms: D002460:Cell Line; D002463:Cell Membrane Permeability; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D008024:Ligands; D008958:Models, Molecular; D018408:Patch-Clamp Techniques; D010627:Phenethylamines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D011485:Protein Binding; D013329:Structure-Activity Relationship; D013449:Sulfonamides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; D005456:Fluorescent Dyes; D007211:Indoles; C000606913:KCNH2 protein, human; D008024:Ligands; D010627:Phenethylamines; D026902:Potassium Channel Blockers; D013449:Sulfonamides; C063533:dofetilide