Water Structures in Protein-Water Mixtures Characterized by Dielectric Spectroscopy with Complementary Techniques

抄録

Time Domain Reflectometry (TDR), Nuclear Magnetic Resonance (NMR), and Molecular Dynamics (MD) simulation were employed to characterize water structures in protein-water mixtures. Dielectric relaxation of water observed by TDR showed broadening of the relaxation time distribution reflecting typical slow dynamics of the water structures in dispersed systems. Water structures of a variety of proteins also can be assessed by the fractal analysis. Corresponding to the slow dynamics, the translational diffusion coefficient of water molecules observed by NMR became smaller as protein concentration increased. We also found an optimal condition in MD simulations of water. Without the combination of these complementary techniques, comprehensive understanding of dynamic structures of water in protein-water mixtures cannot be obtained.