Electrical Conduction of Polypeptides as Related to Molecular Structure

Abstract

The temperature dependence of electric conductivity, the frequency and temperature dependence of the dielectric constant, and the hydrogen–deuterium exchange reaction of the amide group were studied for solid poly(γ-methyl L-glutamate), poly(γ-benzyl L-glutamate), and poly(β-benzyl L-aspartate). A linear relation was found between the activation energy for conductivity and the reciprocal of the static dielectric constant, and was interpreted in terms of the carrier generation process. The conductivity at the glass-like transition temperature was about 3×10−18 ohm−1 cm−1. The generation of protons from the amide groups was concluded to be a source of the charge carriers in solid polypeptides.