Rani Pooja, Biswas Parbati
Department of Chemistry, University of Delhi , Delhi 110007, India.
J Phys Chem B. 2015 Oct 22;119(42):13262-70. doi: 10.1021/acs.jpcb.5b07248. Epub 2015 Oct 8.
Hydration water dynamics around globular proteins have attracted considerable attention in the past decades. This work investigates the hydration water dynamics around partially/fully intrinsically disordered proteins and compares it to that of the globular proteins via molecular dynamics simulations. The translational diffusion of the hydration water is examined by evaluating the mean-square displacement and the velocity autocorrelation function, while the rotational diffusion is probed through the dipole-dipole time correlation function. The results reveal that the translational and rotational motions of water molecules at the surface of intrinsically disordered proteins/regions are less restricted as compared to those around globular proteins/ordered regions, which is reflected in their higher diffusion coefficient and lower orientational relaxation time. The restricted mobility of hydration water in the vicinity of the protein leads to a sublinear diffusion in a heterogeneous interface. A positive correlation between the mean number of hydrogen bonds and the diffusion coefficient of hydration water implies higher mobility of water molecules at the surface of disordered proteins, which is due to their higher number of hydrogen bonds. Enhanced hydration water mobility around disordered proteins/regions is also related to their higher hydration capacity, low hydrophobicity, and increased internal protein motions. Thus, we generalize that the intrinsically disordered proteins/regions are associated with higher hydration water mobility as compared to globular protein/ordered regions, which may help to elucidate their varied functional specificity.
在过去几十年中，球状蛋白周围的水化水动力学引起了相当大的关注。这项工作通过分子动力学模拟研究了部分/完全内在无序蛋白周围的水化水动力学，并将其与球状蛋白的水化水动力学进行了比较。通过评估均方位移和速度自相关函数来研究水化水的平动扩散，而通过偶极 - 偶极时间相关函数来探测转动扩散。结果表明，与球状蛋白/有序区域周围的水分子相比，内在无序蛋白/区域表面的水分子的平动和转动运动受到的限制较少，这体现在它们较高的扩散系数和较低的取向弛豫时间上。蛋白质附近水化水的受限迁移导致在异质界面中的亚线性扩散。氢键平均数与水化水扩散系数之间的正相关意味着无序蛋白表面水分子的迁移率较高，这是由于它们有更多的氢键。无序蛋白/区域周围水化水迁移率的增强也与它们较高的水合能力、低疏水性以及蛋白质内部运动增加有关。因此，我们推断，与球状蛋白/有序区域相比，内在无序蛋白/区域与较高的水化水迁移率相关，这可能有助于阐明它们多样的功能特异性。
