We present a joint experimental and computational study of the dynamic interactions of dialanine (Ala–Ala) with water, comparing the results of ultrafast 2D IR and infrared transient absorption spectroscopy of its amide I vibration with spectra modeled from molecular dynamics (MD) simulations. The experimental data are analyzed to describe vibrational frequency fluctuations, vibrational energy relaxation, and chemical exchange processes. The origin of these processes in the same underlying fluctuating forces allows a common description in terms of the fluctuations and conformational dynamics of the peptide and associated solvent. By comparing computational spectroscopy from MD simulations with multiple force fields and water models, we describe how the dynamics of water hydrogen bond fluctuations and switching processes act as a source of friction that governs the dephasing and vibrational relaxation, and provide a description of coupled water and peptide motions that give rise to spectroscopic exchange processes.
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28 August 2017
Research Article|
August 24 2017
The dynamics of peptide-water interactions in dialanine: An ultrafast amide I 2D IR and computational spectroscopy study
Chi-Jui Feng;
Chi-Jui Feng
Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago
, Chicago, Illinois 60637, USA
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Andrei Tokmakoff
Andrei Tokmakoff
a)
Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago
, Chicago, Illinois 60637, USA
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a)
Author to whom correspondence should be addressed: tokmakoff@uchicago.edu. Telephone: (773) 834-7696.
J. Chem. Phys. 147, 085101 (2017)
Article history
Received:
June 23 2017
Accepted:
August 09 2017
Citation
Chi-Jui Feng, Andrei Tokmakoff; The dynamics of peptide-water interactions in dialanine: An ultrafast amide I 2D IR and computational spectroscopy study. J. Chem. Phys. 28 August 2017; 147 (8): 085101. https://doi.org/10.1063/1.4991871
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