Braun Daniel, Schmollngruber Michael, Steinhauser Othmar
University of Vienna, Faculty of Chemistry, Department of Computational Biological Chemistry, Währinger Straße 17, 1090 Vienna, Austria.
Phys Chem Chem Phys. 2017 Oct 11;19(39):26980-26985. doi: 10.1039/c7cp05216b.
In this computational study, we aim at a complete characterization of the δ-process occurring in dielectric spectroscopy of protein-water systems, with a focus on the consistent interpretation in relation to other experimental observables in the field of biomolecular hydration. A large-scale and long-time molecular dynamics simulation of the protein ubiquitin in aqueous solution offers an adequate basis for the investigation of dielectric properties involving long-ranged and slow collective processes, and their comparison to other experiments calculated from the very same trajectories. An expedient definition of components contributing to the dielectric spectrum reveals at least five different δ-subprocesses. While the previously described cross-correlation between water and protein still plays a major role, we find additional dispersions stemming from protein and water self-correlations. In particular, a contribution of the first hydration shell with moderate retardation relative to bulk water can be linked to the single-particle behavior of water molecules, as observed in magnetic relaxation dispersion. The principle character of the complete δ-process, already once anticipated in experimental literature, is now explicitly calculated and analyzed in great detail, as presented in this study.
在这项计算研究中，我们旨在全面表征蛋白质 - 水系统介电谱中发生的δ过程，重点是与生物分子水合领域的其他实验观测结果进行一致的解释。对水溶液中蛋白质泛素进行的大规模长时间分子动力学模拟，为研究涉及长程和缓慢集体过程的介电性质以及将其与从相同轨迹计算出的其他实验进行比较提供了充分的基础。对介电谱贡献成分的一种便捷定义揭示了至少五个不同的δ子过程。虽然先前描述的水与蛋白质之间的交叉相关性仍然起着主要作用，但我们发现了源于蛋白质和水自相关性的额外色散。特别是，相对于本体水具有适度延迟的第一水合壳的贡献，可以与水分子的单粒子行为相关联，这在磁弛豫色散中也有观察到。完整δ过程的主要特征，在实验文献中已经有所预见，现在在本研究中进行了详细的明确计算和分析。
