Driven diffusion against electrostatic or effective energy barrier across α-hemolysin.
We analyze the translocation of a charged particle across an α-Hemolysin (αHL) pore in the framework of a driven diffusion over an extended energy barrier generated by the electrical charges of the αHL. A one-dimensional electrostatic potential is extracted from the full 3D solution of the Poisson's equation. We characterize the particle transport under the action of a constant forcing by studying the statistics of the translocation time. We derive an analytical expression of translocation time average that compares well with the results from Brownian dynamic simulations of driven particles over the electrostatic potential. Moreover, we show that the translocation time distributions can be perfectly described by a simple theory which replaces the true barrier by an equivalent structureless square barrier. Remarkably, our approach maintains its accuracy also for low-applied voltage regimes where the usual inverse-Gaussian approximation fails. Finally, we discuss how the comparison between the simulated time distributions and their theoretical prediction results to be greatly simplified when using the notion of the empirical Laplace transform technique.
Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, Torino, IT-10135, Italy.
Patrizio
P
Ansalone
Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Via Regina Elena 291, 00161 Roma, Italy.
Mauro
M
Chinappi
Scienze Matematiche, Politecnico di Torino Corso Duca degli Abruzzi 24, Torino, IT-10129, Italy and INFN, Sez. di Torino, Via P. Giuria 1, Torino IT-10125, Italy.
Lamberto
L
Rondoni
CNR-Istituto dei Sistemi Complessi UoS "Sapienza," Via dei Taurini 19, 00185 Roma, Italy.
Fabio
F
Cecconi
D004058:Diffusion; D006460:Hemolysin Proteins / Q000737:chemistry*; D055672:Static Electricity
D006460:Hemolysin Proteins