Dynamic Electric Field Alignment Determines the Water Rotational Motion around Protein

Area of Science:

• Biophysics
• Computational Chemistry
• Structural Biology

Background:

• Water's rotational dynamics are critical for biomolecular stability and function.
• Understanding water-protein interactions is essential in biological systems.
• Previous studies highlight the influence of hydration layers on biomolecule behavior.

Purpose of the Study:

• To investigate the relationship between internal electric fields and water rotational dynamics in lysozyme solutions.
• To elucidate how electric fields dictate water molecule reorientation.
• To correlate simulation findings with experimental measurements like time-dependent fluorescence Stokes shift (TDFSS).

Main Methods:

• Molecular dynamics (MD) simulations of lysozyme in solution.
• Analysis of individual water molecule rotational dynamics.
• Mapping the reorientation of the exerted electric field within the hydration layer.
• Comparison of simulation results with TDFSS data.

Main Results:

• Water molecular rotation synchronizes with the reorientation of the overall electric field.
• Local electric field reorientation dynamics within the hydration layer match experimental TDFSS measurements.
• Outside the hydration layer, electric field reorientation is rapid (subpicosecond), indicating random forces on water molecules.

Conclusions:

• The internal electric field significantly governs water rotational dynamics in biomolecular solutions.
• Water rotation is directly coupled to the local electric field reorientation within the hydration layer.
• This study provides a molecular-level understanding of hydration dynamics relevant to biomolecule stability.