title: Polyelectrolyte entry and transport through an asymmetric alpha-hemolysin channel.
abstract: We study the entry and transport of a polyelectrolyte, dextran sulfate (DS), through an asymmetric alpha-hemolysin protein channel inserted into a planar lipid bilayer. We compare the dynamics of the DS chains as they enter the channel at the opposite stem or vestibule sides. Experiments are performed at the single-molecule level by using an electrical method. The frequency of current blockades varies exponentially as a function of applied voltage. This frequency is smaller for the stem entrance than for the vestibule one, due to a smaller coupling with the electric field and a larger activation energy for entry. The value of the activation energy is quantitatively interpreted as an entropic effect of chain confinement. The translocation time decreases when the applied voltage increases and displays an exponential variation which is independent of the stem or vestibule sides.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Gibrat
authors.forename: Manuela
authors.initials: M
authors.lastname: Pastoriza-Gallego
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Thiebot
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Breton
authors.forename: Loïc
authors.initials: L
authors.lastname: Auvray
authors.forename: Juan
authors.initials: J
authors.lastname: Pelta
mesh_terms: D004573:Electrolytes / Q000737:chemistry*; D006460:Hemolysin Proteins / Q000737:chemistry*; D008051:Lipid Bilayers
chemical_list: D004573:Electrolytes; D006460:Hemolysin Proteins; D008051:Lipid Bilayers