--- res: bibo_abstract: - The combination of high-resolution atomic force microscopy (AFM) imaging and single-molecule force-spectroscopy was employed to unfold single bacteriorhodopsins (BR) from native purple membrane patches at various physiologically relevant temperatures. The unfolding spectra reveal detailed insight into the stability of individual structural elements of BR against mechanical unfolding. Intermittent states in the unfolding process are associated with the stepwise unfolding of alpha-helices, whereas other states are associated with the unfolding of polypeptide loops connecting the alpha-helices. It was found that the unfolding forces of the secondary structures considerably decreased upon increasing the temperature from 8 to 52°C. Associated with this effect, the probability of individual unfolding pathways of BR was significantly influenced by the temperature. At lower temperatures, transmembrane alpha-helices and extracellular polypeptide loops exhibited sufficient stability to individually establish potential barriers against unfolding, whereas they predominantly unfolded collectively at elevated temperatures. This suggests that increasing the temperature decreases the mechanical stability of secondary structural elements and changes molecular interactions between secondary structures, thereby forcing them to act as grouped structures.@eng bibo_authorlist: - 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: Max foaf_name: Kessler, Max foaf_surname: Kessler - foaf_Person: foaf_givenName: Dieter foaf_name: Oesterhelt, Dieter foaf_surname: Oesterhelt - foaf_Person: foaf_givenName: Hermann foaf_name: Gaub, Hermann foaf_surname: Gaub - foaf_Person: foaf_givenName: Daniel foaf_name: Mueller, Daniel J foaf_surname: Mueller bibo_doi: 10.1093/emboj/cdg509 bibo_issue: '19' bibo_volume: 22 dct_date: 2003^xs_gYear dct_publisher: Wiley-Blackwell@ dct_title: Unfolding pathways of native bacteriorhodopsin depend on temperature@ ...