title: Electroosmotic Trap Against the Electrophoretic Force Near a Protein Nanopore Reveals Peptide Dynamics During Capture and Translocation.
abstract: We report on the ability to control the dynamics of a single peptide capture and passage across a voltage-biased, α-hemolysin nanopore (α-HL), under conditions that the electroosmotic force exerted on the analyte dominates the electrophoretic transport. We demonstrate that by extending outside the nanopore, the electroosmotic force is able to capture a peptide at either the lumen or vestibule entry of the nanopore, and transiently traps it inside the nanopore, against the electrophoretic force. Statistical analysis of the resolvable dwell-times of a metastable trapped peptide, as it occupies either the β-barrel or vestibule domain of the α-HL nanopore, reveals rich kinetic details regarding the direction and rates of stochastic movement of a peptide inside the nanopore. The presented approach demonstrates the ability to shuttle and study molecules along the passage pathway inside the nanopore, allows to identify the mesoscopic trajectory of a peptide exiting the nanopore through either the vestibule or β-barrel moiety, thus providing convincing proof of a molecule translocating the pore. The kinetic analysis of a peptide fluctuating between various microstates inside the nanopore, enabled a detailed picture of the free energy description of its interaction with the α-HL nanopore. When studied at the limit of vanishingly low transmembrane potentials, this provided a thermodynamic description of peptide reversible binding to and within the α-HL nanopore, under equilibrium conditions devoid of electric and electroosmotic contributions.
authors.affiliation: Department of Interdisciplinary Research, Alexandru I. Cuza University , Iasi 700506, Romania.
authors.forename: Alina
authors.initials: A
authors.lastname: Asandei
authors.affiliation: Department of Interdisciplinary Research, Alexandru I. Cuza University , Iasi 700506, Romania.
authors.forename: Irina
authors.initials: I
authors.lastname: Schiopu
authors.affiliation: Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia , Roma, Viale Regina Elena 291, 00161 , Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Chinappi
authors.affiliation: Department of Bioinformatics, Kongju National University , Kongju 314-701, South Korea.
authors.forename: Chang Ho
authors.initials: CH
authors.lastname: Seo
authors.affiliation: Department of Biomedical Science and Research Center for Proteineous Materials, Chosun University , Gwangju 61452, South Korea.
authors.forename: Yoonkyung
authors.initials: Y
authors.lastname: Park
authors.affiliation: Department of Physics, Alexandru I. Cuza University , Iasi 700506, Romania.
authors.forename: Tudor
authors.initials: T
authors.lastname: Luchian
mesh_terms: D053841:Electroosmosis; D006460:Hemolysin Proteins / Q000378:metabolism; D007700:Kinetics; D058608:Nanopores; D010455:Peptides / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology*
chemical_list: D006460:Hemolysin Proteins; D010455:Peptides
keywords: electroosmosis; nanopore; peptide transport; single-molecule; α-hemolysin