Dielectric dispersion and dipole moment of myoglobin in water

Abstract

The parameters of dielectric dispersion at radio frequencies in aqueous solutions of horse and sperm whale myoglobin have been measured as functions of protein concentration, solution conductivity and temperature. From these dependences it is shown that, of the likely interpretations, the mechanism of molecular rotation is best able to account for the observed dispersion. The results are consistent with a dipole moment of around 150D for the myoglobin molecule and a hydration shell of about two water molecules thickness. This value of dipole moment is shown to be in good agreement with that obtained from calculations based on the known crystal structure.