High electric field dielectric studies of aqueous myoglobin solutions

Abstract High field dielectric measurements of the Piekara factor Δϵ/ E 2 have been carried out for a range of concentrations of horse heart myoglobin in water at 293 K. Using the literature value for the dipole moment of myoglobin and the established theory for the classical orientational dipolar non-linear effect predicts a value of Δϵ/ E 2 one order of magnitude greater than that for water. The measured effect, however, was found to be one order of magnitude less than for water. This difference is explained as being most probably due to the existence of antiparallel molecular dipole pairs in the myoglobin solution. The possibility of a positive Δϵ due to a field induced conformational change of the myoglobin cannot, however, be ruled out.