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Gas‐Phase Peptide Structures Unraveled by Far‐IR Spectroscopy: Combining IR‐UV Ion‐Dip Experiments with Born–Oppenheimer Molecular Dynamics Simulations
Author(s) -
Jaeqx Sander,
Oomens Jos,
Cimas Alvaro,
Gaigeot MariePierre,
Rijs Anouk M.
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201311189
Subject(s) - molecular dynamics , infrared spectroscopy , chemistry , spectroscopy , chemical physics , spectral line , ion , born–oppenheimer approximation , phase (matter) , two dimensional infrared spectroscopy , peptide , molecular vibration , infrared , computational chemistry , molecule , physics , optics , organic chemistry , biochemistry , quantum mechanics , astronomy
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.