Interactions of a Polypeptide with a Protein Nanopore under Crowding Conditions

Motahareh Ghahari Larimi, Lauren Ashley Mayse, Liviu Movileanu

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Molecular crowding, a ubiquitous feature of the cellular environment, has significant implications in the kinetics and equilibrium of biopolymer interactions. In this study, a single charged polypeptide is exposed to competing forces that drive it into a transmembrane protein pore versus forces that pull it outside. Using single-molecule electrophysiology, we provide compelling experimental evidence that the kinetic details of the polypeptide-pore interactions are substantially affected by high concentrations of less-penetrating polyethylene glycols (PEGs). At a polymer concentration above a critical value, the presence of these neutral macromolecular crowders increases the rate constant of association but decreases the rate constant of dissociation, resulting in a stronger polypeptide-pore interaction. Moreover, a larger-molecular weight PEG exhibits a lower rate constant of association but a higher rate constant of dissociation than those values corresponding to a smaller-molecular weight PEG. These outcomes are in accord with a lower diffusion constant of the polypeptide and higher depletion-attraction forces between the polypeptide and transmembrane protein pore under crowding and confinement conditions.

Original languageEnglish (US)
Pages (from-to)4469-4477
Number of pages9
JournalACS nano
Issue number4
StatePublished - Apr 23 2019


  • free-energy landscape
  • peptide-protein interactions
  • polymer
  • single-channel electrical recordings
  • single-molecule kinetics
  • α-hemolysin

ASJC Scopus subject areas

  • General Materials Science
  • General Engineering
  • General Physics and Astronomy


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