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  More than one dynamic crossover in protein hydration water

Mazza, M. G., Stokely, K., Pagnotta, S. E., Bruni, F., Stanley, H. E., & Franzese, G. (2011). More than one dynamic crossover in protein hydration water. Proceedings of the National Academy of Sciences of the United States of America, 108(50), 19873-19878. doi:10.1073/pnas.1104299108.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-0029-B444-F Version Permalink: http://hdl.handle.net/11858/00-001M-0000-0029-B445-D
Genre: Journal Article

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 Creators:
Mazza, Marco G.1, Author              
Stokely, Kevin, Author
Pagnotta, Sara E., Author
Bruni, Fabio, Author
Stanley, H. Eugene, Author
Franzese, Giancarlo, Author
Affiliations:
1Group Non-equilibrium soft matter, Department of Dynamics of Complex Fluids, Max Planck Institute for Dynamics and Self-Organization, Max Planck Society, ou_2063308              

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Free keywords: hydrated proteins model calculations dielectric relaxation water dynamics water specific heat
 Abstract: Studies of liquid water in its supercooled region have helped us better understand the structure and behavior of water. Bulk water freezes at its homogeneous nucleation temperature (approximately 235 K), but protein hydration water avoids this crystallization because each water molecule binds to a protein. Here, we study the dynamics of the hydrogen bond (HB) network of a percolating layer of water molecules and compare the measurements of a hydrated globular protein with the results of a coarse-grained model that successfully reproduces the properties of hydration water. Using dielectric spectroscopy, we measure the temperature dependence of the relaxation time of proton charge fluctuations. These fluctuations are associated with the dynamics of the HB network of water molecules adsorbed on the protein surface. Using Monte Carlo simulations and mean-field calculations, we study the dynamics and thermodynamics of the model. Both experimental and model analyses are consistent with the interesting possibility of two dynamic crossovers, (i) at approximately 252 K and (ii) at approximately 181 K. Because the experiments agree with the model, we can relate the two crossovers to the presence at ambient pressure of two specific heat maxima. The first is caused by fluctuations in the HB formation, and the second, at a lower temperature, is due to the cooperative reordering of the HB network.

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Language(s): eng - English
 Dates: 2011-12-13
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Method: -
 Identifiers: DOI: 10.1073/pnas.1104299108
BibTex Citekey: mazza_more_2011
 Degree: -

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Title: Proceedings of the National Academy of Sciences of the United States of America
Source Genre: Journal
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Publ. Info: Washington, D.C. : National Academy of Sciences
Pages: - Volume / Issue: 108 (50) Sequence Number: - Start / End Page: 19873 - 19878 Identifier: ISSN: 0027-8424
CoNE: /journals/resource/954925427230