Interaction Enthalpy of Side Chain and Backbone Amides in Polyglutamine Solution Monomers and Fibrils

David Punihaole, Ryan S. Jakubek, Riley J. Workman, Sanford A. Asher

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


We determined an empirical correlation that relates the amide I vibrational band frequencies of the glutamine (Q) side chain to the strength of hydrogen bonding, van der Waals, and Lewis acid-base interactions of its primary amide carbonyl. We used this correlation to determine the Q side chain carbonyl interaction enthalpy (ΔHint) in monomeric and amyloid-like fibril conformations of D2Q10K2 (Q10). We independently verified these ΔHint values through molecular dynamics simulations that showed excellent agreement with experiments. We found that side chain-side chain and side chain-peptide backbone interactions in fibrils and monomers are more enthalpically favorable than are Q side chain-water interactions. Q10 fibrils also showed a more favorable ΔHint for side chain-side chain interactions compared to backbone-backbone interactions. This work experimentally demonstrates that interamide side chain interactions are important in the formation and stabilization of polyQ fibrils.

Original languageEnglish (US)
Pages (from-to)1944-1950
Number of pages7
JournalJournal of Physical Chemistry Letters
Issue number8
StatePublished - Apr 19 2018
Externally publishedYes

ASJC Scopus subject areas

  • General Materials Science
  • Physical and Theoretical Chemistry


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