Probing Dynamics of Hemeproteins in Solution by the High Sensitivity Dielectric Terahertz Spectroscopy

Hemeproteins constitute a large class of biomolecules and play a significant role in diverse and distinct biological functions. Among these, myoglobin and hemoglobin, the tertiary and quaternary protein, are the most popular of the hemoproteins that respectively store and transport of oxygen in mammals. Functions of the proteins are differently performed through the dynamics of proteins in the aqueous solution, which strongly affected by the environmental conditions and temperatures. The difference in the protein structure is expected to have distinctive dynamics in the aqueous environment. Employing the high sensitive megahertz to terahertz dielectric spectroscopy, we are able to collect the complex dielectric response of each solution, analyze the dynamics of the proteins and the hydration shells. Temperature is varied during the experimental study to clarify the effect of temperature on protein functions and dynamics. The results help us to identify the dynamics of the hemeproteins and protein-water interaction that determine biochemical functions and reactivity of proteins.