title: Highly resolved spectra of gas-phase gramicidin s: a benchmark for peptide structure calculations.
abstract: We have measured a vibrationally resolved UV spectrum of doubly protonated gramicidin S (GS) in the gas phase and, subsequently, a highly resolved, conformer-specific IR spectrum in the 6 mum fingerprint region, using a cold ion trap in combination with table-top lasers. The study has revealed at least three conformational states of GS populated under our experimental conditions, with the major one showing evidence of a symmetric three-dimensional structure similar to that in the condensed phase. The derived qualitative constraints, along with the measured vibrational frequencies, serve as a benchmark for computations of peptide structure.
authors.affiliation: Laboratoire de Chimie Physique Moleculaire, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Natalia S
authors.initials: NS
authors.lastname: Nagornova
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Rizzo
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Boyarkin
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry; D005740:Gases; D006096:Gramicidin / Q000737:chemistry*; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D044367:Phase Transition; D013055:Spectrophotometry, Infrared / Q000379:methods; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D014732:Vibration
chemical_list: D000900:Anti-Bacterial Agents; D005740:Gases; D010455:Peptides; D006096:Gramicidin