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Title: Physical origin of hydrophobicity studied in terms of cold denaturation of proteins: comparison between water and simple fluids.
Authors: Yoshidome, Takashi
Kinoshita, Masahiro  kyouindb  KAKEN_id
Author's alias: 木下, 正弘
Issue Date: 31-Aug-2012
Publisher: Royal Society of Chemistry
Journal title: Physical chemistry chemical physics : PCCP
Volume: 14
Issue: 42
Start page: 14554
End page: 14566
Abstract: A clue to the physical origin of the hydrophobicity is in the experimental observations, which show that it is weakened at low temperatures. By considering a solvophobic model protein immersed in water and three species of simple solvents, we analyze the temperature dependence of the changes in free energy, energy, and entropy of the solvent upon protein unfolding. The angle-dependent and radial-symmetric integral equation theories and the morphometric approach are employed in the analysis. Each of the changes is decomposed into two terms, which depend on the excluded volume and on the area and curvature of the solvent-accessible surface, respectively. The excluded-volume term of the entropy change is further decomposed into two components representing the protein-solvent pair correlation and the protein-solvent-solvent triplet and higher-order correlation, respectively. We show that water crowding in the system becomes more serious upon protein unfolding but this effect becomes weaker as the temperature is lowered. If the hydrophobicity originated from the water structuring near a nonpolar solute, it would be strengthened upon lowering of the temperature. Among the three species of simple solvents, considerable weakening of the solvophobicity at low temperatures is observed only for the solvent where the particles interact through a strong attractive potential and the particle size is as small as that of water. Even in the case of this solvent, however, cold denaturation of a protein cannot be reproduced. It would be reproducible if the attractive potential was substantially enhanced, but such enhancement causes the appearance of the metastability limit for a single liquid phase.
Rights: © Royal Society of Chemistry 2012.
This is not the published version. Please cite only the published version. この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。
URI: http://hdl.handle.net/2433/178683
DOI(Published Version): 10.1039/c2cp41738c
PubMed ID: 23014986
Appears in Collections:Journal Articles

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