Temperature and hydration dependence of the complex dielectric spectra of proteins from the sub-GHz to THz frequency region

Abstract

We have performed dielectric spectral measurements of lysozymes to understand the effects of hydration and thermal excitation on the low-frequency dynamics of proteins. Dielectric measurements were performed with changing hydration conditions at room temperature from 0.5GHz to 1.8THz. We also studied the temperature dependence (83K to 293K) of the complex dielectric spectra in the THz frequency region. A protein dynamical transition-like behavior has been also observed in the temperature dependence of the absorption spectra of proteins in the THz frequency region. From our measurements we concluded that the increase in the spectral intensities in the THz region at around 200K is due to the spectral blue-shift of the fast relaxational mode.