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Rhinow D, Imhof M, Chizhik I, Baumann RP, Hampp N. Structural Changes in Bacteriorhodopsin Caused by Two-Photon-Induced Photobleaching. J Phys Chem B 2012; 116:7455-62. [DOI: 10.1021/jp2112846] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Daniel Rhinow
- Department of Structural
Biology, Max-Planck-Institute of Biophysics, Max-von-Laue-Str. 3, D-60438 Frankfurt, Germany
| | - Martin Imhof
- Department of Chemistry, Philipps-University of Marburg, Hans-Meerwein-Str. Bldg. H, D-35032 Marburg,
Germany
| | - Ivan Chizhik
- Department of Chemistry, Philipps-University of Marburg, Hans-Meerwein-Str. Bldg. H, D-35032 Marburg,
Germany
| | - Roelf-Peter Baumann
- Department of Chemistry, Philipps-University of Marburg, Hans-Meerwein-Str. Bldg. H, D-35032 Marburg,
Germany
| | - Norbert Hampp
- Department of Chemistry, Philipps-University of Marburg, Hans-Meerwein-Str. Bldg. H, D-35032 Marburg,
Germany
- Material Sciences Center, D-35032 Marburg, Germany
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Baumann RP, Busch AP, Heidel B, Hampp N. A new class of purple membrane variants for the construction of highly oriented membrane assemblies on the basis of noncovalent interactions. J Phys Chem B 2012; 116:4134-40. [PMID: 22420766 DOI: 10.1021/jp210825x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Purple membranes (PM) from Halobacterium salinarum have been discussed for several technical applications. These ideas started just several years after its discovery. The biological function of bacteriorhodopsin (BR), the only protein in PM, is the light-driven proton translocation across the membrane thereby converting light energy into chemical energy. The astonishing physicochemical robustness of this molecular assembly and the ease of its isolation triggered ideas for technical uses. All basic molecular functions of BR, that is, photochromism, photoelectrism, and proton pumping, are key elements for technical applications like optical data processing and data storage, ultrafast light detection and processing, and direct utilization of sunlight in adenosine 5'-triphospate (ATP) generation or seawater desalination. In spite of the efforts of several research groups worldwide, which confirmed the proof-of-principle for all these potential applications, only the photochromism-based applications have reached a technical level. The physical reason for this is that no fixation or orientation of the PMs is required. The situation is quite different for photoelectrism and proton pumping where the macroscopic orientation of PMs is a prerequisite. For proton pumping, in addition, the formation of artificial membranes which prevent passive proton leakage is necessary. In this manuscript, we describe a new class of PM variants with oppositely charged membrane sides which enable an almost 100% orientation on a surface, which is the key element for photoelectric applications of BR. As an example, the mutated BR, BR-E234R7, was prepared and analyzed. A nearly 100% self-orientation on mica was obtained.
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Affiliation(s)
- Roelf-Peter Baumann
- Philipps University of Marburg, Department of Chemistry, Hans-Meerwein-Str., Bldg. H, D-35032, Germany
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Baumann RP, Eussner J, Hampp N. pH-dependent bending in and out of purple membranes comprising BR-D85T. Phys Chem Chem Phys 2011; 13:21375-82. [DOI: 10.1039/c1cp22098e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Rhinow D, Chizhik I, Baumann RP, Noll F, Hampp N. Crystallinity of Purple Membranes Comprising the Chloride-Pumping Bacteriorhodopsin Variant D85T and Its Modulation by pH and Salinity. J Phys Chem B 2010; 114:15424-8. [DOI: 10.1021/jp108502p] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daniel Rhinow
- Max-Planck-Institute of Biophysics, Department of Structural Biology, Max-von-Laue-Str. 3, D-60438 Frankfurt, Germany, Philipps-University of Marburg, Department of Chemistry, Hans-Meerwein-Str. Bldg. H, D-35032 Marburg, Germany, and Material Sciences Center, D-35032 Marburg, Germany
| | - Ivan Chizhik
- Max-Planck-Institute of Biophysics, Department of Structural Biology, Max-von-Laue-Str. 3, D-60438 Frankfurt, Germany, Philipps-University of Marburg, Department of Chemistry, Hans-Meerwein-Str. Bldg. H, D-35032 Marburg, Germany, and Material Sciences Center, D-35032 Marburg, Germany
| | - Roelf-Peter Baumann
- Max-Planck-Institute of Biophysics, Department of Structural Biology, Max-von-Laue-Str. 3, D-60438 Frankfurt, Germany, Philipps-University of Marburg, Department of Chemistry, Hans-Meerwein-Str. Bldg. H, D-35032 Marburg, Germany, and Material Sciences Center, D-35032 Marburg, Germany
| | - Frank Noll
- Max-Planck-Institute of Biophysics, Department of Structural Biology, Max-von-Laue-Str. 3, D-60438 Frankfurt, Germany, Philipps-University of Marburg, Department of Chemistry, Hans-Meerwein-Str. Bldg. H, D-35032 Marburg, Germany, and Material Sciences Center, D-35032 Marburg, Germany
| | - Norbert Hampp
- Max-Planck-Institute of Biophysics, Department of Structural Biology, Max-von-Laue-Str. 3, D-60438 Frankfurt, Germany, Philipps-University of Marburg, Department of Chemistry, Hans-Meerwein-Str. Bldg. H, D-35032 Marburg, Germany, and Material Sciences Center, D-35032 Marburg, Germany
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Grosfils P, Lutsko JF. Low-density/high-density liquid phase transition for model globular proteins. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:8510-8516. [PMID: 20222718 DOI: 10.1021/la904487z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The effect of molecule size (excluded volume) and the range of interaction on the surface tension, phase diagram, and nucleation properties of a model globular protein is investigated using a combination of Monte Carlo simulations and finite temperature classical density functional theory calculations. We use a parametrized potential that can vary smoothly from the standard Lennard-Jones interaction characteristic of simple fluids to the ten Wolde-Frenkel model for the effective interaction of globular proteins in solution. We find that the large excluded volume characteristic of large macromolecules such as proteins is the dominant effect in determining the liquid-vapor surface tension and nucleation properties. The variation of the range of the potential is important only in the case of small excluded volumes such as for simple fluids. The DFT calculations are then used to study the homogeneous nucleation of the high-density phase from the low-density phase including the nucleation barriers, nucleation pathways, and rate. It is found that the nucleation barriers are typically only a few k(B)T and that the nucleation rates are substantially higher than would be predicted by classical nucleation theory.
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Affiliation(s)
- Patrick Grosfils
- Microgravity Research Center, Chimie Physique E.P. CP 165/62, Université Libre de Bruxelles, Av. F. D. Roosevelt 50, 1050 Brussels, Belgium
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Rhinow D, Hampp N. Curvature of purple membranes comprising permanently wedge-shaped bacteriorhodopsin molecules is regulated by lipid content. J Phys Chem B 2010; 114:549-56. [PMID: 19908872 DOI: 10.1021/jp908408d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Purple membrane (PM) from Halobacterium salinarum has been studied by many groups and is commonly described as a flat 2-D crystalline membrane microdomain which contains a hexagonal crystalline lattice of bacteriorhodopsin (BR) trimers in a stoichiometric ratio of 10:1 between lipids and BR. BR is the key protein in the halobacterial photosynthetic system and acts as a light-driven proton pump. Upon absorption of a photon, BR undergoes a cyclic series of intramolecular changes, among them a transient "wedge-like" geometrical change of the protein due to a tilt in helix F, one of the seven alpha-helical domains of BR. Due to the strong coupling between the BRs in the crystalline lattice, this may affect membrane topography. In nature, only low light levels occur and the total number of BRs in the "wedge-shaped" state is negligible. For mutated PMs like PM-D85T and PM-D85N (PM-D85X, X = neutral residue), the change of the membrane topography can be triggered in a pH-dependent manner. PMs containing BR-D85X look like "cups" at certain pH values. How does nature deal with a mutated PM like PM-D96G/F171C/F219L (PM-Tri) which comprises permanently "wedge-shaped" BRs and how does this influence membrane assembly? Astonishingly, we observed that PM-Tri is flat. Obviously, the morphology of Halobacterium salinarum is highly conserved and requires flat PMs to be assembled. We found that the lipid content of PM-Tri is specifically altered to assemble a hexagonal crystalline PM-Tri lattice of flat topography.
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Affiliation(s)
- Daniel Rhinow
- Department of Chemistry, University of Marburg, Hans-Meerwein-Strasse, D-35032 Marburg, Germany
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Baumann RP, Schranz M, Hampp N. Bending of purple membranes in dependence on the pH analyzed by AFM and single molecule force spectroscopy. Phys Chem Chem Phys 2010; 12:4329-35. [DOI: 10.1039/b919729j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Rhinow D, Vonck J, Schranz M, Beyer A, Gölzhäuser A, Hampp N. Ultrathin conductive carbon nanomembranes as support films for structural analysis of biological specimens. Phys Chem Chem Phys 2010; 12:4345-50. [DOI: 10.1039/b923756a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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