--- res: bibo_abstract: - 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.@eng bibo_authorlist: - foaf_Person: foaf_givenName: Johannes foaf_name: Preiner, Johannes foaf_surname: Preiner - foaf_Person: foaf_givenName: Harald L foaf_name: Harald Janovjak foaf_surname: Janovjak foaf_workInfoHomepage: http://www.librecat.org/personId=33BA6C30-F248-11E8-B48F-1D18A9856A87 orcid: 0000-0002-8023-9315 - foaf_Person: foaf_givenName: Christian foaf_name: Rankl, Christian foaf_surname: Rankl - foaf_Person: foaf_givenName: Helene foaf_name: Knaus, Helene foaf_surname: Knaus - foaf_Person: foaf_givenName: David foaf_name: Cisneros, David A foaf_surname: Cisneros - foaf_Person: foaf_givenName: Alexej foaf_name: Kedrov, Alexej foaf_surname: Kedrov - foaf_Person: foaf_givenName: Ferry foaf_name: Kienberger, Ferry foaf_surname: Kienberger - foaf_Person: foaf_givenName: Daniel foaf_name: Mueller, Daniel J foaf_surname: Mueller - foaf_Person: foaf_givenName: Peter foaf_name: Hinterdorfer, Peter foaf_surname: Hinterdorfer bibo_doi: 10.1529/biophysj.106.096982 bibo_issue: '3' bibo_volume: 93 dct_date: 2007^xs_gYear dct_publisher: Biophysical Society@ dct_title: Free energy of membrane protein unfolding derived from single-molecule force measurements@ ...