title: Vibrational Signatures of Conformer-Specific Intramolecular Interactions in Protonated Tryptophan.
abstract: Because of both experimental and computational challenges, protonated tryptophan has remained the last aromatic amino acid for which the intrinsic structures of low-energy conformers have not been unambiguously solved. The IR-IR-UV hole-burning spectroscopy technique has been applied to overcome the limitations of the commonly used IR-UV double resonance technique and to measure conformer-specific vibrational spectra of TrpH(+), cooled to T = 10 K. Anharmonic ab initio vibrational spectroscopy simulations unambiguously assign the dominant conformers to the two lowest-energy geometries from benchmark coupled-cluster structure computations. The match between experimental and ab initio spectra provides an unbiased validation of the calculated structures of the two experimentally observed conformers of this benchmark ion. Furthermore, the vibrational spectra provide conformer-specific signatures of the stabilizing interactions, including hydrogen bonding and an intramolecular cation-π interaction.
authors.affiliation: Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Federale de Lausanne, EPFL SB ISIC LCPM , Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: Aleksandr Y
authors.initials: AY
authors.lastname: Pereverzev
authors.affiliation: Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States.|Henry Eyring Center for Theoretical Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States.
authors.forename: Xiaolu
authors.initials: X
authors.lastname: Cheng
authors.affiliation: Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Federale de Lausanne, EPFL SB ISIC LCPM , Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: Natalia S
authors.initials: NS
authors.lastname: Nagornova
authors.affiliation: Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States.|Henry Eyring Center for Theoretical Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States.
authors.forename: Diana L
authors.initials: DL
authors.lastname: Reese
authors.affiliation: Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States.|Henry Eyring Center for Theoretical Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States.
authors.forename: Ryan P
authors.initials: RP
authors.lastname: Steele
authors.affiliation: Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Federale de Lausanne, EPFL SB ISIC LCPM , Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Boyarkin
mesh_terms: D011522:Protons; D011789:Quantum Theory; D014364:Tryptophan / Q000737:chemistry*; D014732:Vibration
chemical_list: D011522:Protons; D014364:Tryptophan