Vibrational Signatures of Conformer-Specific Intramolecular Interactions in Protonated Tryptophan

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-pi interaction.


Published in:
Journal of Physical Chemistry
Year:
2016
Publisher:
Washington, Amer Chemical Soc
ISSN:
0022-3654
Laboratories:


Note: The status of this file is: EPFL only


 Record created 2016-07-13, last modified 2018-09-13

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