Terahertz Spectroscopy as a Tool to Study Hydration Dynamics
Peptides and Proteins
Published Online: 15 DEC 2010
Copyright © 2000 John Wiley & Sons, Ltd. All rights reserved.
Encyclopedia of Analytical Chemistry
How to Cite
Heyden, M., Ebbinghaus, S. and Havenith, M. 2010. Terahertz Spectroscopy as a Tool to Study Hydration Dynamics. Encyclopedia of Analytical Chemistry. .
- Published Online: 15 DEC 2010
The role of water in biomolecule dynamics has attracted much interest over the past decade, due in part to new probes of biomolecule–water interactions and developments in molecular simulations. Terahertz (THz) spectroscopy, among the most recent experimental methods brought to bear on this problem, is able to detect even small solute-induced changes of the collective water network dynamics at the biomolecule–water interface. When studying the properties of water in aqueous solutions via THz absorption, proteins show a long-ranged influence on water network dynamics, and even small saccharides influence the dynamics of several hydration layers. The THz spectrum of water solvating a protein is sensitive to mutations and depends on the surface charge and flexibility of the protein. Influence on the solvation shell appears most pronounced for native wild-type proteins and decreases upon partial unfolding or mutation. THz spectra of solvated saccharides reveal that the number of water molecules coupled dynamically to a saccharide forming a dynamic hydration shell around it is related to the number of exposed oxygen atoms on the solute surface. The thickness of this layer appears correlated with the bioprotection efficiency of the saccharide. All findings support the thesis of a long-range dynamic coupling between biomolecules and solvent.
Kinetic terahertz absorption (KITA) studies of protein folding recently revealed that solvent dynamics are coupled to secondary structure formation of the protein. The solvent water network is dynamically rearranged in milliseconds before the protein folds to its native state in the following seconds. THz spectroscopy gives experimental evidence that collective long-range dynamics are a key factor of biomolecular hydration.