Cooperative charge fluctuations by migrating protons in globular proteins

Area of Science:

• Biophysics
• Physical Chemistry
• Protein Dynamics

Background:

• Protein surfaces feature complex hydrogen-bonded networks with ionizable side-chains, water molecules, and peptide backbones.
• These networks exhibit dynamic cooperative effects influencing protein behavior and function.

Purpose of the Study:

• To review the hydrogen-bonded network on protein surfaces.
• To investigate the role of water coverage in protein dynamics and function.
• To explore the statistical physics of cooperative effects on protein surfaces.

Main Methods:

• Review of existing literature on protein surface hydrogen-bonded networks.
• Analysis of lysozyme as a case study for protein dynamics.
• Modeling of protein surface interactions and cooperative effects.

Main Results:

• A percolative transition in bound water clusters was observed with increasing water coverage, linked to proton migration and protein mobility.
• Lowering temperature induced glassy dielectric relaxation in migrating protons, indicating frustrated interactions.
• Dissipative processes imply spontaneous charge fluctuations on the protein surface.

Conclusions:

• Dynamical cooperativity on protein surfaces, driven by water networks and proton migration, is essential for biological function.
• These findings offer insights into enzymatic activity and protein dynamics.
• The study highlights the importance of water-protein interactions in biological systems.