Characterizing Hydration Dynamics and Collective motions of Hemoglobin in Aqueous Solutions using High Sensitivity Dielectric Spectroscopy

Hemoglobin, the dominant component of mammals' red blood cells, is the oxygen and carbon-dioxide transport protein. Hemoglobin physically performs its function by changing the macromolecule shape in response to the change of the surrounding environment. In reality, hemoglobin molecules are surrounded by water molecules, the solvent of life, which is simple in formula but exhibits very complex chemical and physical properties. The incorporating of the complicated quaternary structure of hemoglobin and the hydrogen-bonding in the aqueous environment make a critical challenge in identifying their collective dynamics. Employing highly sensitive dielectric megahertz-to-terahertz frequency-domain spectroscopy, we are able to examine the dynamic of hemoglobin and the hydration structure at the molecular level. Temperature and solvent concentrations have been applied to clarify the effects of living factors on protein functions. The results help us to identify the protein-water interactions and hemoglobin dynamics that determine biochemical functions and reactivity of hemoglobin.