Anomalously Rapid Hydration Water Diffusion Dynamics Near DNA Surfaces.

Area of Science:

• Biophysics
• Chemical Physics
• Molecular Biology

Background:

• The Overhauser effect dynamic nuclear polarization (ODNP) technique probes water mobility near surfaces.
• Understanding water dynamics at DNA surfaces is crucial for molecular interactions.

Purpose of the Study:

• To expand ODNP capabilities for measuring water dynamics at DNA surfaces.
• To investigate the translational mobility of water in the vicinity of DNA duplexes.

Main Methods:

• Attaching nitroxide radicals (spin labels) to DNA phosphate backbones.
• Applying a novel ODNP analysis to differentiate water populations.
• Conducting control studies with tethered DNA and altered nitroxide mobility.

Main Results:

• A significant population of water near DNA surfaces exhibits fast, bulk-like translational diffusion.
• This mobile water moves more rapidly than water near protein or membrane surfaces.
• DNA surfaces interact weakly with a substantial fraction of their hydration water network.

Conclusions:

• DNA surfaces facilitate unusually rapid water diffusion compared to other biomolecular surfaces.
• Weak interactions with surface water can lower activation barriers for DNA-mediated interactions.
• This finding offers new insights into DNA's role in biological processes.