Preiner, Johannes ; Janovjak, Harald LIST Austria ; Rankl, Christian ; Knaus, Helene ; Cisneros, David A ; Kedrov, Alexej ; Kienberger, Ferry ; Mueller, Daniel J ; Hinterdorfer, Peter
Mechanical single-molecule techniques offer exciting possibilities to investigate protein folding and stability in native environments at submolecular resolution. By applying a free-energy reconstruction procedure developed by Hummer and Szabo, which is based on a statistical theorem introduced by Jarzynski, we determined the unfolding free energy of the membrane proteins bacteriorhodopsin (BR), halorhodopsin, and the sodium-proton antiporter NhaA. The calculated energies ranged from 290.5kcal/mol for BR to 485.5kcal/mol for NhaA. For the remarkably stable BR, the equilibrium unfolding free energy was independent of pulling rate and temperature ranging between 18 and 42°C. Our experiments also revealed heterogeneous energetic properties in individual transmembrane helices. In halorhodopsin, the stabilization of a short helical segment yielded a characteristic signature in the energy profile. In NhaA, a pronounced peak was observed at a functionally important site in the protein. Since a large variety of single- and multispan membrane proteins can be tackled in mechanical unfolding experiments, our approach provides a basis for systematically elucidating energetic properties of membrane proteins with the resolution of individual secondary-structure elements.
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Preiner J, Janovjak HL, Rankl C, et al. Free energy of membrane protein unfolding derived from single-molecule force measurements. Biophysical Journal. 2007;93(3):930-937. doi:10.1529/biophysj.106.096982
Preiner, J., Janovjak, H. L., Rankl, C., Knaus, H., Cisneros, D., Kedrov, A., … Hinterdorfer, P. (2007). Free energy of membrane protein unfolding derived from single-molecule force measurements. Biophysical Journal, 93(3), 930–937. https://doi.org/10.1529/biophysj.106.096982
Preiner, Johannes, Harald L Janovjak, Christian Rankl, Helene Knaus, David Cisneros, Alexej Kedrov, Ferry Kienberger, Daniel Mueller, and Peter Hinterdorfer. “Free Energy of Membrane Protein Unfolding Derived from Single-Molecule Force Measurements.” Biophysical Journal 93, no. 3 (2007): 930–37. https://doi.org/10.1529/biophysj.106.096982.
J. Preiner et al., “Free energy of membrane protein unfolding derived from single-molecule force measurements,” Biophysical Journal, vol. 93, no. 3, pp. 930–937, 2007.
Preiner J, Janovjak HL, Rankl C, Knaus H, Cisneros D, Kedrov A, Kienberger F, Mueller D, Hinterdorfer P. 2007. Free energy of membrane protein unfolding derived from single-molecule force measurements. Biophysical Journal. 93(3), 930–937.
Preiner, Johannes, et al. “Free Energy of Membrane Protein Unfolding Derived from Single-Molecule Force Measurements.” Biophysical Journal, vol. 93, no. 3, Biophysical Society, 2007, pp. 930–37, doi:10.1529/biophysj.106.096982.
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