Dielectric relaxation of a proton glass in hydrated protein powders

Dielectric relaxation in the kHz to MHz range displayed by hydrated powders of the protein lysozyme at room temperature is mainly due to protons migra ting between ionized side chains. Quite recently we have measured the frequ ency and temperature dependence of this relaxation, and we have detected th e freezing to a broad distribution of relaxation times, typical of proton g lasses. Below the freezing temperature of about 270 K the system is not erg odic, in analogy with the behavior of proton glass crystals made up by rand om mixtures of ferro- and antiferroelectric compounds. (C) 1999 Published b y Elsevier Science B.V. All rights reserved.