Redox-Promoting Protein Motions in Rubredoxin

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• 作者：Jose M. Borreguero ; Junhong He ; F. Meilleur ; Kevin L. Weiss ; Craig M. Brown ; Dean A. Myles ; Kenneth W. Herwig ; Pratul K. Agarwal
• 刊名：Journal of Physical Chemistry B
• 出版年：2011
• 出版时间：July 21, 2011
• 年：2011
• 卷：115
• 期：28
• 页码：8925-8936
• 全文大小：1134K
• 年卷期：v.115,no.28(July 21, 2011)
• ISSN：1520-5207

文摘

Proteins are dynamic objects, constantly undergoing conformational fluctuations, yet the linkage between internal protein motion and function is widely debated. This study reports on the characterization of temperature-activated collective and individual atomic motions of oxidized rubredoxin, a small 53 residue protein from thermophilic Pyrococcus furiosus (RdPf). Computational modeling allows detailed investigations of protein motions as a function of temperature, and neutron scattering experiments are used to compare to computational results. Just above the dynamical transition temperature which marks the onset of significant anharmonic motions of the protein, the computational simulations show both a significant reorientation of the average electrostatic force experienced by the coordinated Fe³⁺ ion and a dramatic rise in its strength. At higher temperatures, additional anharmonic modes become activated and dominate the electrostatic fluctuations experienced by the ion. At 360 K, close to the optimal growth temperature of P. furiosus, simulations show that three anharmonic modes including motions of two conserved residues located at the protein active site (Ile7 and Ile40) give rise to the majority of the electrostatic fluctuations experienced by the Fe³⁺ ion. The motions of these residues undergo displacements which may facilitate solvent access to the ion.