Enhanced translocation of single DNA molecules through α-hemolysin nanopores by manipulation of internal charge

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Abstract
Both protein and solid-state nanopores are under intense investigation for the analysis of nucleic acids. A crucial advantage of protein nanopores is that site-directed mutagenesis permits precise tuning of their properties. Here, by augmenting the internal positive charge within the alpha-hemolysin pore and varying its distribution, we increase the frequency of translocation of a 92-nt single-stranded DNA through the pore at + 120 mV by approximate to 10-fold over the wild-type protein and dramatically lower the voltage threshold at which translocation occurs, e. g., by 50 mV for 1 event.s(-1).mu M-1. Further, events in which DNA enters the pore, but is not immediately translocated, are almost eliminated. These experiments provide a basis for improved nucleic acid analysis with protein nanopores, which might be translated to solid-state nanopores by using chemical surface modification.