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Three steps in the thermal unfolding of F‐actin: An experimental evidence
Author(s) -
Gicquaud Claude R.,
Heppell Benoit
Publication year - 2006
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.20567
Subject(s) - differential scanning calorimetry , chemistry , denaturation (fissile materials) , actin , biophysics , crystallography , calorimetry , nucleotide , biochemistry , thermodynamics , biology , physics , nuclear chemistry , gene
The development of differential scanning calorimetry has resulted in an increased interest in studies of the unfolding process in proteins with the aim of identifying domains and interactions with ligands or other proteins. Several of these studies were done with actin and showed that the thermal unfolding of F‐actin occurs in at least three steps; this was interpreted as the denaturation of independent domains. In the present work, we have followed the thermal unfolding of F‐actin using differential scanning calorimetry (DSC), CD spectroscopy, and probe fluorescence. We found that the three steps revealed through DSC are not the denaturation of independent domains. These three steps are a change in the environment of cys 374 at 49.5°C; a modification at the nucleotide‐binding site at 55°C; and the unfolding of the peptide chain at 64°C. Previous interpretations of the thermograms of F‐actin were thus erroneous. Since DSC is now widely used to study proteins, our experimental approach and conclusions may also be relevant in denaturation studies of proteins in general. © 2006 Wiley Periodicals, Inc. Biopolymers 83:374–380, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com