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Dynamical Transition in a Small Helical Peptide and Its Implication for Vibrational Energy Transport


Backus, E H G; Bloem, R; Pfister, R; Moretto, A; Crisma, M; Toniolo, C; Hamm, P (2009). Dynamical Transition in a Small Helical Peptide and Its Implication for Vibrational Energy Transport. Journal of Physical Chemistry. B, 113(40):13405-13409.

Abstract

The two-dimensional infrared spectrum of an octameric helical peptide in chloroform was measured as a function of temperature. Isotope labeling of the carbonyl group of one of the amino acids was used to obtain information for an isolated vibration. The antidiagonal width of the 2D-IR signal, which is a measure of the homogeneous dephasing time T2, is constant from 220 to 260 K (within experimental error), and increases steeply above. The homogeneous dephasing time of the carbonyl vibration is attributed to the flexibility of the system and/or its immediate surrounding. The system undergoes a dynamical transition at about 270 K, with similarities to the protein dynamical transition. Furthermore, the temperature dependence of the antidiagonal width strongly resembles that of the efficiency of vibrational energy transport along the helix, which has been studied in a recent paper (J. Phys. Chem. B 2008, 112, 15487). The connection between the two processes, structural flexibility and energy transport mechanism, is discussed.

The two-dimensional infrared spectrum of an octameric helical peptide in chloroform was measured as a function of temperature. Isotope labeling of the carbonyl group of one of the amino acids was used to obtain information for an isolated vibration. The antidiagonal width of the 2D-IR signal, which is a measure of the homogeneous dephasing time T2, is constant from 220 to 260 K (within experimental error), and increases steeply above. The homogeneous dephasing time of the carbonyl vibration is attributed to the flexibility of the system and/or its immediate surrounding. The system undergoes a dynamical transition at about 270 K, with similarities to the protein dynamical transition. Furthermore, the temperature dependence of the antidiagonal width strongly resembles that of the efficiency of vibrational energy transport along the helix, which has been studied in a recent paper (J. Phys. Chem. B 2008, 112, 15487). The connection between the two processes, structural flexibility and energy transport mechanism, is discussed.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:15 September 2009
Deposited On:31 Dec 2009 09:55
Last Modified:05 Apr 2016 13:36
Publisher:American Chemical Society
ISSN:1520-5207
Funders:The Netherlands Organisation for Scientific Research (NWO) , Swiss National Science Foundation
Publisher DOI:10.1021/jp904905d
Permanent URL: http://doi.org/10.5167/uzh-24997

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