Document Detail

Thermodynamics of unfolding of ribonuclease A under high pressure. A study by proton NMR.
MedLine Citation:
PMID:  7623385     Owner:  NLM     Status:  MEDLINE    
Thermodynamic stability of ribonuclease A (6.2 mM pH 1.0, 0.15 M KCl, in 2H2O) has been studied in the pressure range of 1 to 2000 atm and in the temperature range of 7.5 to 40 degrees C with a high pressure 1H NMR technique at 400 MHz. His epsilon proton resonances were used as reporter groups to measure fractions of folded and unfolded species. Gibbs energy differences between folded and unfolded species were obtained as functions of pressure for different temperatures and as functions of temperature for different pressures. The volume increase upon unfolding, delta V, was negative and temperature-dependent, decreasing from -10 ml/mol at 7.5 degrees C to -30 ml/mol at 37 degrees C. From the least squares-fitting of experimental Gibbs energy differences to a theoretical expression holding pressure and delta Cp constant, we determined best-fit values of delta G, delta H, delta S and delta Cp for different values of pressure in the temperature range 7.5 to 40 degrees C. We found that delta Cp is dependent on pressure, decreasing from 1.79 kcal/mol K at 1 atm to 1.08 kcal/mol K at 2000 atm. These findings appear to be consistent with a notion that the state of hydration of non-polar side-chains upon unfolding of the protein is a major factor that determines the pressure dependence of the conformational stability of ribonuclease A under the chosen experimental condition.
T Yamaguchi; H Yamada; K Akasaka
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of molecular biology     Volume:  250     ISSN:  0022-2836     ISO Abbreviation:  J. Mol. Biol.     Publication Date:  1995 Jul 
Date Detail:
Created Date:  1995-08-31     Completed Date:  1995-08-31     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985088R     Medline TA:  J Mol Biol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  689-94     Citation Subset:  IM    
Division of Material Science, Graduate School of Science and Technology Kobe University, Japan.
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MeSH Terms
Magnetic Resonance Spectroscopy / methods
Protein Folding*
Ribonuclease, Pancreatic / chemistry*
Reg. No./Substance:
EC, Pancreatic

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