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Molten globule–like transition state of protein barnase measured with calorimetric force spectroscopy

Understanding how proteins fold into their native structure is a fundamental problem in biophysics, crucial for protein design. It has been hypothesized that the formation of a molten globule intermediate precedes folding to the native conformation of globular proteins; however, its thermodynamic pr...

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Detalles Bibliográficos
Autores principales: Rico-Pasto, Marc, Zaltron, Annamaria, Davis, Sebastian J., Frutos, Silvia, Ritort, Felix
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8931224/
https://www.ncbi.nlm.nih.gov/pubmed/35271392
http://dx.doi.org/10.1073/pnas.2112382119
Descripción
Sumario:Understanding how proteins fold into their native structure is a fundamental problem in biophysics, crucial for protein design. It has been hypothesized that the formation of a molten globule intermediate precedes folding to the native conformation of globular proteins; however, its thermodynamic properties are poorly known. We perform single-molecule pulling experiments of protein barnase in the range of 7 (∘)C to 37 (∘)C using a temperature-jump optical trap. We derive the folding free energy, entropy and enthalpy, and heat capacity change ([Formula: see text] = 1,050 ± 50 cal/mol [Formula: see text] K) at low ionic strength conditions. From the measured unfolding and folding kinetic rates, we also determine the thermodynamic properties of the transition state, finding a significant change in [Formula: see text] (∼90%) between the unfolded and the transition states. In contrast, the major change in enthalpy (∼80%) occurs between the transition and native states. These results highlight a transition state of high energy and low configurational entropy structurally similar to the native state, in agreement with the molten globule hypothesis.