Energy Transport in Peptide Helices: A Comparison between High- and Low-Energy Excitations (Articolo in rivista)

Type
Label
  • Energy Transport in Peptide Helices: A Comparison between High- and Low-Energy Excitations (Articolo in rivista) (literal)
Anno
  • 2008-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1021/jp711046e (literal)
Alternative label
  • Ellen H.G. Backus; Phuong H. Nguyen; Virgiliu Botan; Rolf Pfister; Alessandro Moretto; Marco Crisma; Claudio Toniolo; Gerhard Stock; Peter Hamm (2008)
    Energy Transport in Peptide Helices: A Comparison between High- and Low-Energy Excitations
    in The journal of physical chemistry. B
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Ellen H.G. Backus; Phuong H. Nguyen; Virgiliu Botan; Rolf Pfister; Alessandro Moretto; Marco Crisma; Claudio Toniolo; Gerhard Stock; Peter Hamm (literal)
Pagina inizio
  • 9091 (literal)
Pagina fine
  • 9099 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 112 (literal)
Rivista
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroFascicolo
  • 30 (literal)
Note
  • Scopu (literal)
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Physikalisch-Chemisches Institut, Universität Zürich, CH-8057 Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland; Institute of Biomolecular Chemistry, Padova Unit, CNR, Department of Chemistry, University of Padova, Via Marzolo 1, I-35131 PadoVa, Italy; Institut für Physikalische and Theoretische Chemie, J. W. Goethe Universität, Max-Von-Laue-Strasse 7, D-60438 Frankfurt, Germany (literal)
Titolo
  • Energy Transport in Peptide Helices: A Comparison between High- and Low-Energy Excitations (literal)
Abstract
  • Energy transport in a short helical peptide in chloroform solution is studied by time-resolved femtosecond spectroscopy and accompanying nonequilibrium molecular dynamics (MD) simulations. In particular, the heat transport after excitation of an azobenzene chromophore attached to one terminus of the helix with 3 eV (UV) photons is compared to the excitation of a peptide C=O oscillator with 0.2 eV (IR) photons. The heat in the helix is detected at various distances from the heat source as a function of time by employing vibrational pump-probe spectroscopy. As a result, the carbonyl oscillators at different positions along the helix act as local thermometers. The experiments show that heat transport through the peptide after excitation with low-energy photons is at least 4 times faster than after UV excitation. On the other hand, the heat transport obtained by nonequilibrium MD simulations is largely insensitive to the kind of excitation. The calculations agree well with the experimental results for the low-frequency case; however, they give a factor of 5 too fast energy transport for the high-energy case. Employing instantaneous normal mode calculations of the MD trajectories, a simple harmonic model of heat transport is adopted, which shows that the heat diffusivity decreases significantly at temperatures initially reached by high-energy excitation. This finding suggests that the photoinduced energy gets trapped, if it is deposited in high amounts. The various competing mechanisms, such as vibrational T(1) relaxation, resonant transfer between excitonic states, cascading down relaxation, and low-frequency mode transfer, are discussed in detail. (literal)
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