Protein transport through a narrow solid-state nanopore at high voltage: experiments and theory.
We report experimentally the transport of an unfolded protein through a narrow solid-state nanopore of 3 nm diameter as a function of applied voltage. The random coil polypeptide chain is larger than the nanopore. The event frequency dependency of current blockades from 200 to 750 mV follows a van't Hoff-Arrhenius law due to the confinement of the unfolded chain. The protein is an extended conformation inside the pore at high voltage. We observe that the protein dwell time decreases exponentially at medium voltage and is inversely proportional to voltage for higher values. This is consistent with the translocation mechanism where the protein is confined in the pore, creating an entropic barrier, followed by electrophoretic transport. We compare these results to our previous work with a larger pore of 20 nm diameter. Our data suggest that electro-osmotic flow and protein adsorption on the narrowest nanopore wall are minimized. We discuss the experimental data obtained as compared with recent theory for the polyelectrolyte translocation process. This theory reproduces clearly the experimental crossover between the entropic barrier regime with medium voltage and the electrophoretic regime with higher voltage.
LAMBE UMR CNRS 8587, Université d'Evry et de Cergy-Pontoise, France.
Benjamin
B
Cressiot
Abdelghani
A
Oukhaled
Gilles
G
Patriarche
Manuela
M
Pastoriza-Gallego
Jean-Michel
JM
Betton
Loïc
L
Auvray
Murugappan
M
Muthukumar
Laurent
L
Bacri
Juan
J
Pelta
D004560:Electricity; D029968:Escherichia coli Proteins / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D015233:Models, Statistical; D058608:Nanopores; D036103:Nanotechnology; D033902:Periplasmic Binding Proteins / Q000737:chemistry; D011487:Protein Conformation; D017510:Protein Folding; D021381:Protein Transport
D029968:Escherichia coli Proteins; C461619:MalE protein, E coli; D033902:Periplasmic Binding Proteins