Document Detail

High-pressure SAXS study of folded and unfolded ensembles of proteins.
MedLine Citation:
PMID:  21081092     Owner:  NLM     Status:  MEDLINE    
A structural interpretation of the thermodynamic stability of proteins requires an understanding of the structural properties of the unfolded state. High-pressure small-angle x-ray scattering was used to measure the effects of temperature, pressure, denaturants, and stabilizing osmolytes on the radii of gyration of folded and unfolded state ensembles of staphylococcal nuclease. A set of variants with the internal Val-66 replaced with Ala, Tyr, or Arg was used to examine how changes in the volume and polarity of an internal microcavity affect the dimensions of the native state and the pressure sensitivity of the ensemble. The unfolded state ensembles achieved for these proteins with high pressure were more compact than those achieved at high temperature, and were all very sensitive to the presence of urea and glycerol. Substitutions at the hydrophobic core detectably altered the conformation of the protein, even in the folded state. The introduction of a charged residue, such as Arg, inside the hydrophobic interior of a protein could dramatically alter the structural properties, even those of the unfolded state. The data suggest that a charge at an internal position can interfere with the formation of transient hydrophobic clusters in the unfolded state, and ensure that the pressure-unfolded form of a protein occupies the maximum volume possible. Only at high temperatures does the radius of gyration of the unfolded state ensemble approach the value for a statistical random coil.
Martin A Schroer; Michael Paulus; Christoph Jeworrek; Christina Krywka; Saskia Schmacke; Yong Zhai; D C Florian Wieland; Christoph J Sahle; Michael Chimenti; Catherine A Royer; Bertrand Garcia-Moreno; Metin Tolan; Roland Winter
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biophysical journal     Volume:  99     ISSN:  1542-0086     ISO Abbreviation:  Biophys. J.     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-11-18     Completed Date:  2011-03-02     Revised Date:  2013-07-03    
Medline Journal Info:
Nlm Unique ID:  0370626     Medline TA:  Biophys J     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3430-7     Citation Subset:  IM    
Copyright Information:
Copyright © 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.
Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany.
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MeSH Terms
Atmospheric Pressure*
Calorimetry, Differential Scanning
Hydrogen-Ion Concentration
Micrococcal Nuclease / chemistry*,  metabolism*
Mutant Proteins / chemistry,  metabolism
Protein Structure, Secondary
Protein Unfolding*
Scattering, Small Angle*
X-Ray Diffraction / methods*
Reg. No./Substance:
0/Mutant Proteins; 0/Solvents; EC Nuclease

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