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Issue 17, 2010
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Bending of purple membranes in dependence on the pH analyzed by AFM and single molecule force spectroscopy

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Abstract

The first AFM images of strongly bent purple membranes as well as the first single molecule force spectra of bacteriorhodopsins embedded therein are presented. AFM images of purple membranes to date always showed a flat membrane topology. Bacteriorhodopsin variants like BR-D85N and BR-D85T resemble an intermediate state of wild-type BR which is slightly ‘wedge’-shaped. Due to the strong interaction within the 2-D crystalline lattice of the purple membrane, the geometrical anisotropy of the individual bacteriorhodopsins adds up to a macroscopic change in the geometry of the purple membranes. Instead of being flat they appear like domes at physiological conditions. Single molecule force spectroscopy was employed to determine the absolute sign of the membrane curvature. As the bacteriorhodopsins in the center of the dome-like purple membranes are not supported by any solid state substrate, the presented force spectra are the first of non-supported bacteriorhodopsin, resembling the natural occurrence in the halobacterial cell.

Graphical abstract: Bending of purple membranes in dependence on the pH analyzed by AFM and single molecule force spectroscopy

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Publication details

The article was received on 22 Sep 2009, accepted on 18 Jan 2010 and first published on 23 Feb 2010


Article type: Paper
DOI: 10.1039/B919729J
Citation: Phys. Chem. Chem. Phys., 2010,12, 4329-4335
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    Bending of purple membranes in dependence on the pH analyzed by AFM and single molecule force spectroscopy

    R.-P. Baumann, M. Schranz and N. Hampp, Phys. Chem. Chem. Phys., 2010, 12, 4329
    DOI: 10.1039/B919729J

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