Sensing Single Protein Molecules with Solid-State Nanopores - Nanopores: Sensing and Fundamental Biological Interactions - page 145

Fig. 6.7 Time duration histograms of unfolded proteins with Hpr that has one stalling point
(a) and b GLa that has two stalling points (b); uniformly charged dsDNA with no stall point: 2.7 kb
(c) and 7.0 kb (d); native state BSA as a charged particle at pH 7 (e) and pH 4.5 (f). The solid
curves are fittings to exponentials for unfolded proteins (a) and (b). The rest of the panels are
fittings to Eq. (6.6) and the pore effective thickness H eff ¼ 20 nm was used for the fittings
6.7 Summary
Nanopore translocation of native state protein molecules can be treated as the biased
1D diffusion of simple charged particles if the proteins are stable with respect to
electrostatically induced denaturation. Uniformly charged polymer translocation
also follows 1D biased diffusion. The kinetic behavior of unfolded protein translo-
cation is highly dependent on the sequence of charged residues. These observations
are in sharp contrast to DNA translocation. When calculating the driving force for
DNA translocation, the thickness of the pore cancels out because of the uniform
charge density; there is essentially no DNA sequence effect on the translocation