Dynamics of a Form-Fitting Protein in a Nanopore: Avidin in ClyA

Abstract

We probe the molecular dynamics of a protein, avidin, as it is captured and trapped in a nanopore, ClyA, with time-resolved single-molecule electrical conductance measurements, and we present a method for visualizing this process from the data. The case of avidin in ClyA has rich time-dependent conductance spectra of discrete levels that correlate with different configurations of the protein in the pore. One is very long-lasting, stable and noise-free, and portends the use of this system as a platform for more general studies of proteins and other molecules, where avidin acts as a shuttle that ferries analytes into the pore for probing. We demonstrate this by the sensitive detection of a biotin molecule attached to avidin captured by the pore. We also present an approach to determining the nanopore size based on a 3D printed model of the pore.