Proteins in Solutions and Natural Membranes

In the first part of the chapter, dielectric spectroscopy studies of globular proteins in aqueous solutions in native and denatured states are reviewed. Here we discuss the mechanisms of two major dielectric relaxation processes (γ- and β-dispersions) and one minor process (δ-dispersion) observed in the diluted globular protein solutions. Effects of protein concentration, temperature, pH, and denaturants were also summarized. The second part of the chapter presents the dielectric properties of proteins in natural membrane fragments and living cells membrane. Ferroelectric behavior was observed for the first time for the package of bacteriorhodopsin membrane fragments oriented in the electric field. Here, a discussion is also presented about progress and problems related to the observation of proteins in living cells using dielectric spectroscopy