Molten globule–like transition state of protein barnase measured with calorimetric force spectroscopy
| Autor: | Marc Rico-Pasto, Annamaria Zaltron, Sebastian J. Davis, Silvia Frutos, Felix Ritort |
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| Rok vydání: | 2022 |
| Předmět: |
folding
Protein Denaturation Protein Folding Optical Tweezers Protein Conformation denaturation FOS: Physical sciences Calorimetry Condensed Matter - Soft Condensed Matter single-molecule experiments molten globule thermodynamics Ribonucleases Bacterial Proteins intermediate Quantitative Biology::Biomolecules Multidisciplinary energy landscape optical-trap folding pathways transition state Single Molecule Imaging heat-capacity temperature-dependence kinetics Soft Condensed Matter (cond-mat.soft) protein |
| Zdroj: | Proceedings of the National Academy of Sciences. 119 |
| ISSN: | 1091-6490 0027-8424 |
| Popis: | 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$^\circ$C to 37$^\circ$C using a temperature-jump optical trap. We derive the folding free energy, entropy and enthalpy, and heat capacity change ($\Delta C_p = 1050\pm50$ cal/mol$\cdot$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 $\Delta C_p$ ($\sim$ 90$\%$) between the unfolded and the transition states. In contrast, the major change in enthalpy ($\sim$ 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. Comment: 10 pages, 6 figures |
| Databáze: | OpenAIRE |
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