Hydration water dynamics around a protein surface: a first passage time approach

Area of Science:

• Physical Chemistry
• Biophysics
• Computational Biology

Background:

• Water molecules surrounding proteins (hydration water) play a crucial role in protein function.
• Understanding hydration water dynamics is essential for deciphering protein behavior and interactions.
• Thermal fluctuations and molecular collisions influence water molecule movement.

Purpose of the Study:

• To develop a dynamic model for water diffusion around protein surfaces.
• To investigate the impact of thermally correlated noise on hydration water dynamics.
• To analyze non-Markovian behavior and subdiffusive characteristics of hydration water.

Main Methods:

• Stochastic noise-driven dynamic model.
• Generalized Langevin equation framework.
• Analysis of mean-square displacement and velocity autocorrelation function.
• Derivation of analytical expressions for first passage time, survival probability, and mean first passage time.

Main Results:

• Hydration water exhibits subdiffusive dynamics at long times.
• First passage time distribution is unimodal, deviating from Brownian motion.
• Survival probability follows a stretched exponential decay.
• Mean residence time and mean first passage time are influenced by environmental complexity and boundary conditions.

Conclusions:

• The proposed model accurately captures the subdiffusive and non-Markovian behavior of hydration water.
• Thermally correlated noise significantly alters water molecule dynamics compared to simple Brownian motion.
• Environmental complexity and hydration layer thickness impact water diffusion and residence times near proteins.