title: Polarity-dependent conformational switching of a peptide mimicking the S4-S5 linker of the voltage-sensitive sodium channel.
abstract: The S4-S5 linker (or S45) in voltage-sensitive sodium channels was previously shown to be involved in the permeation pathway. The secondary structure, investigated by circular dichroism, of a S4-S45 peptide from domain IV and its fragments (including S45) is reported here and compared with that of the homologous peptide from domain II as a function of the solvent dielectric constant. The reduction in helicity seen for S4-S45 (II) in polar media is cancelled in membrane-like environment. The most striking result-- a sharp alpha-helix --> beta-sheet transition upon exposure of the S45 moiety to aqueous solvents-- is discussed as regards channel activation and selectivity.
authors.affiliation: URA 500 CNRS-Université de Rouen, Mont-Saint-Aignan, France.
authors.forename: O
authors.initials: O
authors.lastname: Helluin
authors.forename: J
authors.initials: J
authors.lastname: Breed
authors.forename: H
authors.initials: H
authors.lastname: Duclohier
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D015222:Sodium Channels / Q000737:chemistry*
chemical_list: D010446:Peptide Fragments; D015222:Sodium Channels