All-Atom Molecular Dynamics Simulations of Peptide Amphiphile Assemblies That Spontaneously Form Twisted and Helical Ribbon Structures

Cheng Tsung Lai, Nathaniel L. Rosi, George C. Schatz*

*Corresponding author for this work

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

Self-assembly of peptide amphiphiles (PAs) has been an active research area as the assemblies can be programmed into variously shaped nanostructures. Although cylindrical micelles are common structures, gold-binding peptide conjugates can self-assemble into chiral nanofibers with single or double helices. When gold nanoparticles bind to the helices, the resulting chiral nanoparticle assemblies have a collective plasmonic circular dichroism signal that can serve as nanoscale circular polarizers or chiroptical sensors. A better atomic-level understanding of the factors which lead to helical PA assemblies is therefore of significant importance. In this study we show that all-atom molecular dynamics simulations can describe the spontaneous structural transformation from a planar assembly of PAs to a twisted assembly or to a helical ribbon. The twist angle and the helical diameter calculated from the simulations closely match the experimental results, with the oxidation of a single Met residue in each PA leading to a change from bilayer to monolayer assemblies with significantly different ribbon properties. A secondary structure analysis shows how a combination of β-sheet formation near the hydrophobic core of the micelle and PPII structures from proline-rich C-terminus regions favors helix formation. The simulations presented here demonstrate the capability of predicting self-assembly in chiral structures, protocols that can easily be applied to the assembly of other amphiphilic molecules.

Original languageEnglish (US)
Pages (from-to)2170-2174
Number of pages5
JournalJournal of Physical Chemistry Letters
Volume8
Issue number10
DOIs
StatePublished - May 18 2017

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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