Hydration Water Dynamics Near Biological Interfaces

Abstract

We performed classical molecular dynamics simulations using both fixed-charge and polarizable water and protein force fields to contrast the hydration dynamics near hydrophilic and amphiphilic peptides as a function of temperature. The high peptide concentrations we use serve as a model for the surface of folded proteins where hydration layers around each residue overlap significantly. Through simulation we determine that there are notable differences in the water dynamics analyzed from the outer and inner hydration layer regions of the amphiphilic peptide solution that explains the experimentally observed presence of two translational relaxations, while the hydrophilic peptide solution shows only a single non-Arrhenius translational process with no distinction between hydration layers. Given that water dynamics for the amphiphilic peptide system reproduces all known rotational and translational hydration dynamical anomalies exhibited by hydration water near protein surfaces, our analysis provides strong evidence that dynamical signatures near biological interfaces arises because of frustration in the hydration dynamics induced by chemical heterogeneity, as opposed to just topological roughness, of the protein surface.

Site-Specific Hydration Dynamics in the Nonpolar Core of a Molten Globule by Dynamic Nuclear Polarization of Water

“…At the same time, the observation of heterogeneous surface hydration dynamics, especially in the N state, emphasizes the importance of employing site-specific probes as charge, polarity, local structural, and chemical topology may all contribute to distinct variations in local water dynamics 24,31,32 . The τ values of 190 and 300 ps for E41R1 and V66R1, respectively, are about 2–4 times slower than the measured τ value of bulk water 48,87 , in agreement with previous results that surface hydration water is slowed by a factor of 2–5 compared to bulk water 20,32,37,81 .…”

Mechanism of atomic force microscopy imaging of three-dimensional hydration structures at a solid-liquid interface

“…Despite the wide success of diffraction and spectroscopy techniques in investigating hydration structures at the nanoscale [7][8][9][10][11][12][13], molecular level detail of water distributions at critical inhomogeneous interfaces remains elusive. Recent developments in frequency modulation AFM (FM-AFM) [14] have enabled subnanometer-scale measurements of 3D force distributions at solid-liquid interfaces [15].…”

Analysis of Water and Hydrogen Bond Dynamics at the Surface of an Antifreeze Protein

“…Coupling of protein and water dynamics, for example, has been examined by molecular simulations [1][2][3][4][5][6][7][8][9][10] and a growing number of experimental probes [11][12][13][14], and a wide variety of dynamical time scales have been found [15,16] due to the heterogeneity of protein-water interactions. One class of proteins for which protein-water interactions are critical to function is antifreeze proteins (AFPs).…”