Berlin 2012 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 7: Posters: Proteins
BP 7.6: Poster
Montag, 26. März 2012, 17:30–19:30, Poster A
Molecular Dynamics Simulations of Hydrated Proteins: Possible Origins of a Logarithmic Protein Relaxation. — •Kerstin Kämpf and Michael Vogel — TU Darmstadt, Institut für Festkörperphysik, 64289 Darmstadt
Biological function is the consequence of protein fluctuations in a complex energy landscape. An unresolved puzzle of protein dynamics is the origin of a strongly nonexponential relaxation observed over several orders of magnitude in time.
In order to elucidate this phenomenon, we perform molecular dynamics simulations of hydrated elastin and myoglobin. It is observed that the orientational and translational correlation functions of the protein backbone are well described by a power law [1] or a logarithmic decay [2]. Assuming a heterogeneous origin of the power-law decay, we analyze the temperature dependent mean relaxation rates. An Arrhenius behavior with an activation energy Ea≈0.25 eV is obtained, corresponding to the energy necessary to break a hydrogen bond. Fitting to a logarithmic decay, we tested whether the predictions of the mode-coupling theory are fulfilled. We investigate further how far the dynamics of hydrated proteins resemble that of other complex systems.
Finally, we calculate multi-time correlation functions to determine the relevance of homogeneous and heterogeneous contribution to the strongly nonexponential decay. This analysis allows to characterize the complex energy landscape and thus to shed light on the nature of the microscopic processes underlying protein function.
[1] Iben et al. PRL 62, 1916. [2] Lagi et al, PRL, 103, 108102.