Diffusion of Hydration Water around Intrinsically Disordered Proteins

Area of Science:

• Biophysics
• Structural Biology
• Computational Chemistry

Background:

• Hydration water dynamics around proteins are crucial for biological functions.
• Intrinsically disordered proteins (IDPs) lack stable tertiary structures, unlike globular proteins.
• Understanding water-protein interactions is key to deciphering protein behavior.

Purpose of the Study:

• To investigate and compare hydration water dynamics around IDPs and globular proteins.
• To elucidate the relationship between protein structure (disordered vs. ordered) and water molecule mobility.
• To explore how water dynamics influence protein functional specificity.

Main Methods:

• Molecular dynamics (MD) simulations were employed.
• Translational diffusion was analyzed using mean-square displacement and velocity autocorrelation functions.
• Rotational diffusion was assessed via dipole-dipole time correlation functions.

Main Results:

• Water molecules at the surface of IDPs show less restricted translational and rotational motion compared to globular proteins.
• IDPs exhibit higher diffusion coefficients and lower orientational relaxation times for hydration water.
• A positive correlation exists between hydrogen bond number and water diffusion coefficient around IDPs.

Conclusions:

• Intrinsically disordered proteins/regions are associated with significantly higher hydration water mobility than globular proteins/regions.
• Enhanced water mobility around IDPs is attributed to increased hydrogen bonding, hydration capacity, and internal protein dynamics.
• This difference in hydration dynamics may explain the diverse functional roles of IDPs.