Single-molecule force spectroscopy of membrane proteins from membranes freely spanning across nanoscopic pores.

Petrosyan, Rafayel; Bippes, Christian A; Walheim, Stefan; Harder, Daniel; Fotiadis, Dimitrios José; Schimmel, Thomas; Alsteens, David; Müller, Daniel J (2015). Single-molecule force spectroscopy of membrane proteins from membranes freely spanning across nanoscopic pores. Nano letters, 15(5), pp. 3624-3633. American Chemical Society 10.1021/acs.nanolett.5b01223

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Single-molecule force spectroscopy (SMFS) provides detailed insight into the mechanical (un)folding pathways and structural stability of membrane proteins. So far, SMFS could only be applied to membrane proteins embedded in native or synthetic membranes adsorbed to solid supports. This adsorption causes experimental limitations and raises the question to what extent the support influences the results obtained by SMFS. Therefore, we introduce here SMFS from native purple membrane freely spanning across nanopores. We show that correct analysis of the SMFS data requires extending the worm-like chain model, which describes the mechanical stretching of a polypeptide, by the cubic extension model, which describes the bending of a purple membrane exposed to mechanical stress. This new experimental and theoretical approach allows to characterize the stepwise (un)folding of the membrane protein bacteriorhodopsin and to assign the stability of single and grouped secondary structures. The (un)folding and stability of bacteriorhodopsin shows no significant difference between freely spanning and directly supported purple membranes. Importantly, the novel experimental SMFS setup opens an avenue to characterize any protein from freely spanning cellular or synthetic membranes.

Item Type:

Journal Article (Original Article)


04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Biochemistry and Molecular Medicine

UniBE Contributor:

Harder, Daniel, Fotiadis, Dimitrios José


500 Science > 570 Life sciences; biology
600 Technology > 610 Medicine & health




American Chemical Society




Barbara Franziska Järmann-Bangerter

Date Deposited:

26 Feb 2016 13:39

Last Modified:

05 Dec 2022 14:51

Publisher DOI:


PubMed ID:


Uncontrolled Keywords:

AFM; atomic force microscopy; freely spanning membrane; molecular interactions; polymer blend lithography; unfolding intermediates




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