  The passage of DNA through a nanopore can be effectively decomposed into two
distinct phases, docking and actual translocation. In experiments each phase is
characterized by a distinct current signature which allows the discrimination
of the two events. However, at low voltages a clear distinction of the two
phases is lost. By using numerical simulations we clarify how the current
signature associated to the docking events depends on the applied voltage. The
simulations show that at small voltage the DNA globule enhances the pore
conductance due to an enrichment of charge carriers. At high voltage, the
globule drains substantial charge carriers from the pore region, thereby
reducing the overall conductance. The results provide a new interpretation to
the experimental data on conductance and show how docking interferes with the
translocation signal, of potential interest for sequencing applications.
