title: Gas-phase peptide structures unraveled by far-IR spectroscopy: combining IR-UV ion-dip experiments with Born-Oppenheimer molecular dynamics simulations.
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. Although the far-IR region (<500 cm(-1)) may contain a wealth of structural information, as recognized in condensed phase studies, 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.
authors.affiliation: Radboud University Nijmegen, Institute for Molecules and Materials, FELIX facility Toernooiveld 7, 6525 ED Nijmegen (The Netherlands).
authors.forename: Sander
authors.initials: S
authors.lastname: Jaeqx
authors.forename: Jos
authors.initials: J
authors.lastname: Oomens
authors.forename: Alvaro
authors.initials: A
authors.lastname: Cimas
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Gaigeot
authors.forename: Anouk M
authors.initials: AM
authors.lastname: Rijs
mesh_terms: D000577:Amides / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D010455:Peptides / Q000737:chemistry*; D013055:Spectrophotometry, Infrared / Q000379:methods*; D014732:Vibration
chemical_list: D000577:Amides; D005740:Gases; D010455:Peptides
keywords: IR spectroscopy; conformation analysis; molecular dynamics; peptides; structure elucidation