title: Proton glass freezing in hydrated lysozyme powders.
abstract: At room temperature, the dielectric relaxation of hydrated powder of the protein lysozyme is known to be due to protons migrating between ionized side chains. A recent study of this relaxation at lower temperatures suggested a behavior typical of proton glasses. An analysis of the complex dielectric susceptibility by a temperature-frequency plot presented here has revealed that ergodicity is broken due to the divergence of the longest relaxation time at 266 K, indicating specifically that this hydrated protein is a proton glass. A change in the temperature behavior of the static dielectric constant and the average relaxation frequency at 273 K indicates a further transition occurring at this temperature, whose nature remains to be investigated.
authors.affiliation: Jozef Stefan Institute, P.O. Box 3000, 1001 Ljubljana, Slovenia.
authors.forename: A
authors.initials: A
authors.lastname: Levstik
authors.forename: C
authors.initials: C
authors.lastname: Filipic
authors.forename: Z
authors.initials: Z
authors.lastname: Kutnjak
authors.forename: G
authors.initials: G
authors.lastname: Careri
authors.forename: G
authors.initials: G
authors.lastname: Consolini
authors.forename: F
authors.initials: F
authors.lastname: Bruni
mesh_terms: D005615:Freezing; D005898:Glass / Q000737:chemistry*; D009113:Muramidase / Q000737:chemistry*; D011208:Powders / Q000737:chemistry*; D011522:Protons; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D011208:Powders; D011522:Protons; D014867:Water; D009113:Muramidase