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Glassy behavior of a percolative water-protein system.

Authors
  • Pagnotta, S E
  • Gargana, R
  • Bruni, F
  • Bocedi, A
Type
Published Article
Journal
Physical Review E
Publisher
American Physical Society (APS)
Publication Date
Mar 01, 2005
Volume
71
Issue
3 Pt 1
Pages
31506–31506
Identifiers
PMID: 15903434
Source
Medline
License
Unknown

Abstract

We show that is possible to look at the glass transition as a percolation transition in phase space. This study has been carried out on a hydrated globular enzyme for which the thermodynamic transition and the percolative transition could have a functional significance. The approach adopted is based on the identity of roles played respectively by the glass transition temperature T(o) and the critical hydration threshold h(c) for the percolation of protons on the surface and through the protein, given that dynamical arrest is observed at temperatures and hydration below T(o) and h(c). Theoretical predictions for temperature dependence of the nonexponentiality parameter, beta(KWW) , appearing in the KWW relaxation function, indicate that at high temperatures, beta(KWW) remains insensitive to temperature changes, whereas in the vicinity of the glass transition, beta(KWW) is linearly increasing with temperature. The low temperature limit of beta(KWW) is about 1/3 and its temperature-independent behavior starts at 1.23 T(g): both predictions have been verified in the present study.

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