Electrical unfolding of cytochrome <i>c</i> during translocation through a nanopore constriction
Prabhat Tripathi, Abdelkrim Benabbas, Behzad Mehrafrooz, Hirohito Yamazaki, Aleksei Aksimentiev, P. M. Champion, Meni Wanunu
Abstract
is thermodynamically stabilized, facilitating its translocation. In contrast, for 1.5- and 2.0-nm-diameter pores, translocation occurs only by threading of the fully unfolded protein after it transitions through a higher energy unfolding intermediate state at the mouth of the pore. The relative energies between the metastable, intermediate, and unfolded protein states are extracted using a simple thermodynamic model that is dictated by the relatively slow (∼ms) protein translocation times for passing through the nanopore. These experiments map the various modes of protein translocation through a constriction, which opens avenues for exploring protein folding structures, internal contacts, and electric-field-induced deformability.