Document Detail


Comparing proteins by their unfolding pattern.
MedLine Citation:
PMID:  18550806     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Single molecule force spectroscopy has evolved into an important and extremely powerful technique for investigating the folding potentials of biomolecules. Mechanical tension is applied to individual molecules, and the subsequent, often stepwise unfolding is recorded in force extension traces. However, because the energy barriers of the folding potentials are often close to the thermal energy, both the extensions and the forces at which these barriers are overcome are subject to marked fluctuations. Therefore, force extension traces are an inadequate representation despite widespread use particularly when large populations of proteins need to be compared and analyzed. We show in this article that contour length, which is independent of fluctuations and alterable experimental parameters, is a more appropriate variable than extension. By transforming force extension traces into contour length space, histograms are obtained that directly represent the energy barriers. In contrast to force extension traces, such barrier position histograms can be averaged to investigate details of the unfolding potential. The cross-superposition of barrier position histograms allows us to detect and visualize the order of unfolding events. We show with this approach that in contrast to the sequential unfolding of bacteriorhodopsin, two main steps in the unfolding of the enzyme titin kinase are independent of each other. The potential of this new method for accurate and automated analysis of force spectroscopy data and for novel automated screening techniques is shown with bacteriorhodopsin and with protein constructs containing GFP and titin kinase.
Authors:
Elias M Puchner; Gereon Franzen; Mathias Gautel; Hermann E Gaub
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biophysical journal     Volume:  95     ISSN:  1542-0086     ISO Abbreviation:  Biophys. J.     Publication Date:  2008 Jul 
Date Detail:
Created Date:  2008-06-13     Completed Date:  2008-07-10     Revised Date:  2010-09-22    
Medline Journal Info:
Nlm Unique ID:  0370626     Medline TA:  Biophys J     Country:  United States    
Other Details:
Languages:  eng     Pagination:  426-34     Citation Subset:  IM    
Affiliation:
Lehrstuhl für Angewandte Physik and Center for Nanoscience, LMU München, Munich, Germany. elias.puchner@physik.lmu.de
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MeSH Terms
Descriptor/Qualifier:
Algorithms*
Computer Simulation
Microscopy, Atomic Force / methods*
Models, Chemical*
Models, Molecular*
Protein Denaturation*
Protein Folding*
Proteins / chemistry*,  ultrastructure*
Chemical
Reg. No./Substance:
0/Proteins
Comments/Corrections

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