Gas-phase peptide structures unraveled by far-IR spectroscopy: Combining IR-UV ion-dip experiments with born-oppenheimer molecular dynamics simulations

Sander Jaeqx, Jos Oomens, Alvaro Cimas, Marie Pierre Gaigeot*, Anouk M. Rijs

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Vibrational spectroscopy provides an important probe of the three-dimensional structures of peptides. With increasing size, these IR spectra become very complex and to extract structural information, comparison with theoretical spectra is essential. Harmonic DFT calculations have become a common workhorse for predicting vibrational frequencies of small neutral and ionized gaseous peptides.1 Although the far-IR region (<500 cm-1) may contain a wealth of structural information, as recognized in condensed phase studies,2 DFT often performs poorly in predicting the far-IR spectra of peptides. Here, Born-Oppenheimer molecular dynamics (BOMD) is applied to predict the far-IR signatures of two γ-turn peptides. Combining experiments and simulations, far-IR spectra can provide structural information on gas-phase peptides superior to that extracted from mid-IR and amide A features. The use of low-frequency modes (towards 100 cm-1) for structural assignment of peptides is explored. This far-IR region possibly contains detailed information on the secondary structure. The use of Born-Oppenheimer molecular dynamics simulations is discussed to calculate the far-IR signature of peptides.

Original languageEnglish
Pages (from-to)3663-3666
Number of pages4
JournalAngewandte Chemie - International Edition
Volume53
Issue number14
DOIs
Publication statusPublished - 1 Apr 2014
Externally publishedYes

Keywords

  • conformation analysis
  • IR spectroscopy
  • molecular dynamics
  • peptides
  • structure elucidation

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