Dielectric properties of protein–methylglyoxal adducts. Interfacial and bulk effects

Abstract

Steady-state electrical conduction and dielectric measurements over the frequency range 10^–5–10⁵ Hz are reported for polycrystalline samples of protein–methylglyoxal adducts. The results are found to be influenced by sample heterogeneity effects associated with a chemical instability that results in the formation of resistive layers at sample surfaces exposed to air. The conductivity data confirm earlier reports regarding the action of methylglyoxal in increasing the electrical conductivity of proteins, and an analysis of possible interfacial effects indicates that the increased conductivity and observed dielectric dispersions are associated with a true bulk phenomenon.