Critical structural fluctuations of proteins upon thermal unfolding challenge the Lindemann criterion

Internal subnanosecond timescale motions are key for the function of proteins, and are coupled to the surrounding solvent environment. These fast fluctuations guide protein conformational changes, yet their role for protein stability, and for unfolding, remains elusive. Here, in analogy with the Lin...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2017-08, Vol.114 (35), p.9361-9366
Main Authors: Katava, Marina, Stirnemann, Guillaume, Zanatta, Marco, Capaccioli, Simone, Pachetti, Maria, Ngai, K. L., Sterpone, Fabio, Paciaroni, Alessandro
Format: Article
Language:English
Subjects:
Biological Sciences
Chemical Sciences
Computer Simulation
Criteria
Egg Proteins - chemistry
Egg Proteins - metabolism
Elastic scattering
Entropy
Fluctuations
Lysozyme
Melting
Models, Chemical
Models, Molecular
Molecular structure
Muramidase - chemistry
Muramidase - metabolism
Neutron scattering
Neutrons
or physical chemistry
Protein Conformation
Protein folding
Protein Stability
Protein Unfolding
Proteins
Scaling
Scattering
Solvation
Solvents
Studies
Temperature
Theoretical and
Transition Temperature
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Summary:Internal subnanosecond timescale motions are key for the function of proteins, and are coupled to the surrounding solvent environment. These fast fluctuations guide protein conformational changes, yet their role for protein stability, and for unfolding, remains elusive. Here, in analogy with the Lindemann criterion for the melting of solids, we demonstrate a common scaling of structural fluctuations of lysozyme protein embedded in different environments as the thermal unfolding transition is approached. By combining elastic incoherent neutron scattering and advanced molecular simulations, we show that, although different solvents modify the protein melting temperature, a unique dynamical regime is attained in proximity of thermal unfolding in all solvents that we tested. This solvation shell-independent dynamical regime arises from an equivalent sampling of the energy landscape at the respective melting temperatures. Thus, we propose that a threshold for the conformational entropy provided by structural fluctuations of proteins exists, beyond which thermal unfolding is triggered.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1707357114