Mechanical and chemical unfolding of a single protein: A comparison

Citation
M. Carrion-vazquez et al., Mechanical and chemical unfolding of a single protein: A comparison, P NAS US, 96(7), 1999, pp. 3694-3699
Citations number
31
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
ISSN journal
00278424 → ACNP
Volume
96
Issue
7
Year of publication
1999
Pages
3694 - 3699
Database
ISI
SICI code
0027-8424(19990330)96:7<3694:MACUOA>2.0.ZU;2-O
Abstract
Is the mechanical unraveling of protein domains by atomic force microscopy (AFM) just a technological feat or a true measurement of their unfolding? B y engineering a protein made of tandem repeats of identical Ig modules, we were able to get explicit AFM data on the unfolding rate of a single protei n domain that can be accurately extrapolated to zero force. We compare this with chemical unfolding rates for untethered modules extrapolated to 0 M d enaturant. The unfolding rates obtained by the two methods are the same. Fu rthermore, the transition state for unfolding appears at the same position on the folding pathway when assessed by either method, These results indica te that mechanical unfolding of a single protein by AFM does indeed reflect the same event that is observed in traditional unfolding experiments, The way is now open for the extensive use of AFM to measure folding reactions a t the single-molecule level. Single-molecule AFM recordings have the added advantage that they define the reaction coordinate and expose rare unfoldin g events that cannot be observed in the absence of chemical denaturants.