Nonlinear dielectric response of dilute protein solutions

A theory for the nonlinear dielectric response of dilute protein solutions is presented. The field-dependent dielectric function of the protein solution changes linearly with the electric field squared in the lowest order. The slope of this dependence is expressed in terms of the protein dipole moment M-0, its volume fraction in solution eta(0), and the second osmotic virial coefficient. For practical conditions, the nonlinear dielectric response scales as eta M-3(0)0(8). This strong dependence on the protein dipole moment and concentration establishes a sharp contrast between the nonlinear response of solvated proteins relative to the surrounding polar solvent. Nonlinear dielectric response can serve as a sensitive tool for monitoring protein conformations and physiological activity.

Automated summary

A theory for the nonlinear dielectric response of dilute protein solutions is presented, which shows that the field-dependent dielectric function of the protein solution changes linearly with the electric field squared. The dependence is determined by the protein dipole moment, volume fraction, and the second osmotic virial coefficient. Under practical conditions, the nonlinear dielectric response is strongly correlated with the protein dipole moment and concentration.