Role of side-chain interactions on the formation of α -helices in model peptides

Farbod Mahmoudinobar, Cristiano L. Dias, Ronen Zangi

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5 Scopus citations


The role played by side-chain interactions on the formation of α-helices is studied using extensive all-atom molecular dynamics simulations of polyalanine-like peptides in explicit TIP4P water. The peptide is described by the OPLS-AA force field except for the Lennard-Jones interaction between Cβ-Cβ atoms, which is modified systematically. We identify values of the Lennard-Jones parameter that promote α-helix formation. To rationalize these results, potentials of mean force (PMF) between methane-like molecules that mimic side chains in our polyalanine-like peptides are computed. These PMF exhibit a complex distance dependence where global and local minima are separated by an energy barrier. We show that α-helix propensity correlates with values of these PMF at distances corresponding to Cβ-Cβ of i-i+3 and other nearest neighbors in the α-helix. In particular, the set of Lennard-Jones parameters that promote α-helices is characterized by PMF that exhibit a global minimum at distances corresponding to i-i+3 neighbors in α-helices. Implications of these results are discussed.

Original languageEnglish (US)
Article number032710
JournalPhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
Issue number3
StatePublished - Mar 25 2015

All Science Journal Classification (ASJC) codes

  • Statistical and Nonlinear Physics
  • Statistics and Probability
  • Condensed Matter Physics


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