Biophysical Characterization of Peptides and Their Interaction with Lysenin Nanopores

Translocation of single molecules through biological nanopores provides valuable information about the physical and chemical structure of analytes. Such nanopores have been envisioned as tools for sequencing, biosensing, or characterization of biological interactions. However, many biological nanopores have limitations in regard to undesirable interactions with analytes, difficult insertion, and low transport potential. To overcome these issues, we examined lysenin, a pore-forming protein from the earthworm E. foetida , which self-inserts 3 nm diameter pores into lipid membranes containing sphingomyelin. In this work, we investigated translocation of peptides through lysenin channels. The first peptide we studied, WWHPC, can manifest as a monomer or dimer. Our other peptide, HMWWM, occurs only as a monomer. By using the resistive pulse technique, lysenin is able to distinguish between these two forms. In conclusion, these results show that lysenin can be used as a single molecule biosensor and for single molecule characterization.