Martin Daniel R, Matyushov Dmitry V
Department of Physics, Arizona State University, PO Box 871504, Tempe, Arizona 85287-1504, USA.
Department of Physics and Department of Chemistry and Biochemistry, Arizona State University, PO Box 871504, Tempe, Arizona 85287-1504, USA.
J Chem Phys. 2014 Dec 14;141(22):22D501. doi: 10.1063/1.4895544.
Water interfacing hydrated proteins carry properties distinct from those of the bulk and is often described as a separate entity, a "biological water." We address here the question of which dynamical and structural properties of hydration water deserve this distinction. The study focuses on different aspects of the density and orientational fluctuations of hydration water and the ability to separate them experimentally by combining depolarized light scattering with dielectric spectroscopy. We show that the dynamics of the density fluctuations of the hydration shells reflect the coupled dynamics of the solute and solvent and do not require a special distinction as "biological water." The orientations of shell water molecules carry dramatically different physics and do require a separation into a sub-ensemble. Depending on the property considered, the perturbation of water's orientational structure induced by the protein propagates 3-5 hydration shells into the bulk at normal temperature.
与水合蛋白质相互作用的水具有与主体水不同的性质，常被描述为一个独立的实体，即“生物水”。我们在此探讨水合水的哪些动力学和结构性质值得这种区分。该研究聚焦于水合水密度和取向涨落的不同方面，以及通过将去偏振光散射与介电谱相结合来实验分离它们的能力。我们表明，水合壳层密度涨落的动力学反映了溶质和溶剂的耦合动力学，不需要作为“生物水”进行特殊区分。壳层水分子的取向具有截然不同的物理性质，确实需要分为一个子集合。根据所考虑的性质，在常温下，蛋白质引起的水取向结构的扰动会向主体水传播3 - 5个水合壳层。
