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Title: Probing Solvation-Induced Structural Changes in Conformationally Flexible Peptides: IR Spectroscopy of Gly3H+•(H2O)

Abstract

IR predissociation spectroscopy of the Gly3H+(H2O) complex formed inside of a cryogenic ion trap reveals how the flexible model peptide structurally responds to solvation by a single water molecule. The resulting one-laser spectrum is quite congested, and the spectral analyses were assisted by both H2O/D2O substitution and IR–IR double resonance spectroscopy, revealing the presence of two contributing isomers and extensive anharmonic features. Comparisons to structures found via a systematic computational search identified the geometries of these two isomers. The major isomer, with all trans amide bonds and protonation on the terminal amine, represents ~90% of the overall population. It noticeably differs from the unsolvated Gly3H+, which exists in two isomeric forms: one with a cis amide bond and the other with protonation on an amide C=O. These results indicate that interactions with just one water molecule can induce significant structural changes, i.e., cis–trans amide bond rotation and proton migration, even as the clustering occurs within an 80 K cryogenic ion trap. In conclusion, calculations of the isomerization pathways further reveal that the binding energy of the water molecule provides sufficient internal energy to overcome the barriers for the observed structural changes, and the minor solvation isomer results from a smallmore » fraction of the ions being kinetically trapped along one of the pathways.« less

Authors:
 [1];  [1];  [1]; ORCiD logo [1]
  1. Univ. of Wisconsin-Madison, Madison, WI (United States)
Publication Date:
Research Org.:
Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1513761
Grant/Contract Number:  
SC0010326
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
Additional Journal Information:
Journal Volume: 122; Journal Issue: 41; Journal ID: ISSN 1089-5639
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Fischer, Kaitlyn C., Voss, Jonathan M., Zhou, Jia, and Garand, Etienne. Probing Solvation-Induced Structural Changes in Conformationally Flexible Peptides: IR Spectroscopy of Gly3H+•(H2O). United States: N. p., 2018. Web. https://doi.org/10.1021/acs.jpca.8b07546.
Fischer, Kaitlyn C., Voss, Jonathan M., Zhou, Jia, & Garand, Etienne. Probing Solvation-Induced Structural Changes in Conformationally Flexible Peptides: IR Spectroscopy of Gly3H+•(H2O). United States. https://doi.org/10.1021/acs.jpca.8b07546
Fischer, Kaitlyn C., Voss, Jonathan M., Zhou, Jia, and Garand, Etienne. Fri . "Probing Solvation-Induced Structural Changes in Conformationally Flexible Peptides: IR Spectroscopy of Gly3H+•(H2O)". United States. https://doi.org/10.1021/acs.jpca.8b07546. https://www.osti.gov/servlets/purl/1513761.
@article{osti_1513761,
title = {Probing Solvation-Induced Structural Changes in Conformationally Flexible Peptides: IR Spectroscopy of Gly3H+•(H2O)},
author = {Fischer, Kaitlyn C. and Voss, Jonathan M. and Zhou, Jia and Garand, Etienne},
abstractNote = {IR predissociation spectroscopy of the Gly3H+(H2O) complex formed inside of a cryogenic ion trap reveals how the flexible model peptide structurally responds to solvation by a single water molecule. The resulting one-laser spectrum is quite congested, and the spectral analyses were assisted by both H2O/D2O substitution and IR–IR double resonance spectroscopy, revealing the presence of two contributing isomers and extensive anharmonic features. Comparisons to structures found via a systematic computational search identified the geometries of these two isomers. The major isomer, with all trans amide bonds and protonation on the terminal amine, represents ~90% of the overall population. It noticeably differs from the unsolvated Gly3H+, which exists in two isomeric forms: one with a cis amide bond and the other with protonation on an amide C=O. These results indicate that interactions with just one water molecule can induce significant structural changes, i.e., cis–trans amide bond rotation and proton migration, even as the clustering occurs within an 80 K cryogenic ion trap. In conclusion, calculations of the isomerization pathways further reveal that the binding energy of the water molecule provides sufficient internal energy to overcome the barriers for the observed structural changes, and the minor solvation isomer results from a small fraction of the ions being kinetically trapped along one of the pathways.},
doi = {10.1021/acs.jpca.8b07546},
journal = {Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory},
number = 41,
volume = 122,
place = {United States},
year = {2018},
month = {9}
}

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Cited by: 4 works
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Figures / Tables:

Figure 1 Figure 1: Structures of Gly3H+ identified in a previous study. Relative energies (in kJ/mol, unscaled ZPE corrected) calculated at cam-B3LYP/def2TZVPP and MP2/def2TZVPP (in parentheses) are listed.

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Works referencing / citing this record:

Introductory lecture: advances in ion spectroscopy: from astrophysics to biology
journal, January 2019

  • Zeng, Helen J.; Yang, Nan; Johnson, Mark A.
  • Faraday Discussions, Vol. 217
  • DOI: 10.1039/c9fd00030e

    Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.