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Purple Membrane (0):
Recent article
Purple Membrane
Abstract
A poly-L-lysine (PLL)/bacteriorhodopsin-embedded purple membrane (bR-PM) multilayer film has been successfully constructed by a layer-by-layer (LbL) assembly process to enhance the photoelectric response of bR. The assembly conditions were investigated and optimized. The PLL/bR-PM adsorption process...
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PMID: 20056227
PDF is available here.
PDF is available here.
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Biochemistry (New York) (74)12 2009
Abstract
We have investigated the character of melittin-regenerated purple membrane. Adding melittin to blue membrane causes the color transition and partial regeneration of the photocycle and the proton pump. The reconstitution of bacteriorhodopsin by melittin is proved to be charge-dependent. In studying t...
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PMID: 19961420
PDF is available here.
PDF is available here.
Physical Review Letters (102)6 2009
Abstract
We demonstrate a new scanning probe spectroscopy capable of resolving with high sensitivity the variations in the elasticity of soft biological materials in liquids....
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PMID: 19257574
PDF is available here.
PDF is available here.
Faraday Discussions (141) 2009
Abstract
An integrated picture of hydration shell dynamics and of its coupling to functional macromolecular motions is proposed from studies on a soluble protein, on a membrane protein in its natural lipid environment, and on the intracellular environment in bacteria and red blood cells. Water dynamics in mu...
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PMID: 19227354
PDF is available here.
PDF is available here.
Faraday Discussions (141) 2009
Abstract
We report a molecular dynamics simulation study of the dynamics of water hydrating purple membranes (PM). We validate our simulations by comparing the temperature and hydration dependence of crystal lattice parameters and water and protein/lipid dynamics with neutron diffraction and spectroscopic da...
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PMID: 19227353
PDF is available here.
PDF is available here.
Biochemistry (Washington) (47)42 2008
Abstract
We were unable to correlate it with any FTIR-detectable transition of the lipids. Therefore, we attribute the change from distributed to conventional kinetics to a thermodynamic phase transition in the protein. Most probably, it is related to the freezing and thawing of internal fluctuations of the...
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PMID: 18821776
PDF is available here.
PDF is available here.
Abstract
These results are informative for future work on bioconjugation of BR as well as work on oriented assembly and the design of BR-based photoelectric devices....
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PMID: 18619849
PDF is available here.
PDF is available here.
Journal of Molecular Biology (380)3 2008
Abstract
Components of biological macromolecules, complexes and membranes are animated by motions occurring over a wide range of time and length scales, the synergy of which is at the basis of biological activity. Understanding biological function thus requires a detailed analysis of the underlying dynamical...
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PMID: 18565346
PDF is available here.
PDF is available here.
Biophysical Journal (95)1 2008
Abstract
We used neutron scattering and specific hydrogen-deuterium labeling to investigate the thermal dynamics of isotope-labeled amino acids and retinal, predominantly in the active core and extracellular moiety of bacteriorhodopsin (BR) in the purple membrane and the dynamical response to hydration. Meas...
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PMID: 18339747
PDF is available here.
PDF is available here.
Ultramicroscopy (108)7 2008
Abstract
We conclude that TiSi support films are ideal for high-resolution electron cryo-microscopy (cryo-EM) of biological specimens, as they reduce beam-induced movement significantly, due to their high electrical conductivity at low temperature and their favorable mechanical properties....
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PMID: 18164549
PDF is available here.
PDF is available here.
Abstract
We have measured the dynamics of PM and water separately, at a low-hydration level corresponding to the first layer of hydration water only. As in the case of the higher hydration samples previously studied, the dynamics of PM and water display different temperature dependencies, with a transition i...
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PMID: 18286273
PDF is available here.
PDF is available here.
Abstract
We report an investigation of this contact effect on electronic transport properties using metal-insulator-metal planar junctions with a 5 nm thick bacteriorhodopsin-based insulator as model system. We demonstrate that the experimentally observed rectifying behavior is not an intrinsic property of t...
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PMID: 18399666
PDF is available here.
PDF is available here.
Abstract
Solid state NMR spectra from uniformly (13)C, (15)N enriched bacteriorhodospin (bR) purified from H. salinarium were acquired at 18.8 T using magic angle spinning methods. Isolated resonances of 2D (13)C-(13)C spectra exhibited 0.50-0.55 ppm line-widths. Several amino acid types could be assigned, a...
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PMID: 18427930
PDF is available here.
PDF is available here.
Biophysical Journal (94)9 2008
Abstract
The membrane protein bacteriorhodopsin (BR) can be kept soluble in its native state for months in the absence of detergent by amphipol (APol) A8-35, an amphiphilic polymer. After an actinic flash, A8-35-complexed BR undergoes a complete photocycle, with kinetics intermediate between that in detergen...
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PMID: 18192360
PDF is available here.
PDF is available here.
Journal of Physical Chemistry B (112)15 2008
Abstract
The formation of blue membrane from purple membranes (PM) has been observed in glassy films made from PM and various sugars. The phase transition of PM at about 70 degrees C causes the complexation of divalent cations to be weakened. The vicinal diol structures in sugars are capable to complex dival...
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PMID: 18358028
PDF is available here.
PDF is available here.
Journal of Molecular Biology (375)5 2008
Abstract
Archaerhodopsin-2 (aR2), a retinal protein-carotenoid complex found in the claret membrane of Halorubrum sp. aus-2, functions as a light-driven proton pump. In this study, the membrane fusion method was utilized to prepare trigonal P321 crystals (a=b=98.2 A, c=56.2 A) and hexagonal P6(3) crystals (a...
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PMID: 18082767
PDF is available here.
PDF is available here.
Acta Crystallographica Section A (64)Pt 1 2008
Abstract
Following the seminal work of Von Dreele, powder X-ray diffraction studies on proteins are being established as a valuable complementary technique to single-crystal measurements. A wide range of small proteins have been found to give synchrotron powder diffraction profiles where the peak widths are...
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PMID: 18156682
PDF is available here.
PDF is available here.
Acta Crystallographica Section A (64)Pt 1 2008
Abstract
Methods of contrast variation are tools that are essential in macromolecular structure research. Anomalous dispersion of X-ray diffraction is widely used in protein crystallography. Recent attempts to extend this method to native resonant labels like sulfur and phosphorus are promising. Substitution...
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PMID: 18156683
PDF is available here.
PDF is available here.
Biochemistry (77) 2008
Abstract
Evolution has tuned membrane proteins to exist in a lipid bilayer, provide for cell-cell communication, transport solutes, and convert energies. These proteins exhibit a hydrophobic belt that interacts with the lipid bilayer. Detergents are therefore used to extract membrane proteins and keep them i...
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PMID: 18518819
PDF is available here.
PDF is available here.
Biochimica et Biophysica Acta (1768)12 2007
Abstract
The effect of deuteration on the 13C linewidths of U-13C, 15N 2D crystalline bacteriorhodopsin (bR) from Halobacterium salinarium, a 248-amino acid protein with seven-transmembrane (7TM) spanning regions, has been studied in purple membranes as a prelude to potential structural studies. Spectral dou...
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PMID: 18001693
PDF is available here.
PDF is available here.
Abstract
Highly oriented monolayers of bacteriorhodopsin (BR) in purple membrane (PM) form are obtained by the reaction of BR-Q3C, where a cysteine was introduced into the N-terminal region, with a gold surface. Single molecule force spectroscopy was used to show that about 50% of the BRs are covalently boun...
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PMID: 17887782
PDF is available here.
PDF is available here.
Biophysical Journal (93)6 2007
Abstract
We show that tryptophan (Trp) residues use steric specific interactions to create a rigid scaffold in bR extracellular region and are responsible for the main unfolding barriers. This scaffold, which encloses the retinal, controls bR local mechanical properties and anchors the protein into the membr...
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PMID: 17513362
PDF is available here.
PDF is available here.
Biochimica et Biophysica Acta (1768)9 2007
Abstract
We show that purple membranes isolated from envelopes have a lower content of glycocardiolipin than standard purple membranes isolated from cells. The properties of bacteriorhodopsin in the two different purple membrane preparations are compared; although some differences in the absorption spectrum...
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PMID: 17669358
PDF is available here.
PDF is available here.
Journal of Molecular Biology (371)4 2007
Abstract
We investigated the influence of hydration water on the relationship between structure, dynamics and function in a biological membrane system. For the example of the purple membrane (PM) with its protein bacteriorhodopsin (BR), a light-driven proton pump, complementary information from neutron diffr...
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PMID: 17599349
PDF is available here.
PDF is available here.
Abstract
We have studied multilamellar phospholipid membrane stacks with reconstituted transmembrane protein bacteriorhodopsin (BR) under different illumination conditions by X-ray scattering. The light-active protein is considered as an active constituent which drives the system out of equilibrium and is pr...
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PMID: 17712523
PDF is available here.
PDF is available here.
Abstract
We describe a rapid cooperative assembly process directed by universal electrostatic interactions that spontaneously organizes proteorhodopsin molecules into ordered arrays with well defined orientation and packing density. We demonstrate the charge density-matching mechanism that selectively contro...
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PMID: 17488827
PDF is available here.
PDF is available here.
Abstract
The present work describes the results of a study aimed at identifying candidate cation binding sites on the extracellular region of bacteriorhodopsin, including a site near the retinal pocket. The approach used is a combined effort involving computational chemistry methods (computation of cation af...
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PMID: 17266122
PDF is available here.
PDF is available here.
Journal of Molecular Biology (368)3 2007
Abstract
The behavior of the D115A mutant was analyzed by time-resolved UV-Vis and Fourier transformed infrared (FTIR) spectroscopies, aiming to clarify the role of Asp115 in the intra-protein signal transductions occurring during the bacteriorhodopsin photocycle. UV-Vis data on the D115A mutant show severel...
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PMID: 17367807
PDF is available here.
PDF is available here.
Abstract
Earlier it was an orthodoxy that purple membranes (PMs) in aqueous medium are shaped as flat hard disks. In a few newer articles it has been shown that PMs are bent and their curvature varies with surface charge density. The purpose of this work is to answer which is the dominant factor for PM bendi...
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PMID: 17218085
PDF is available here.
PDF is available here.
Abstract
We proved that the membrane surfaces with flat topography were on the extracellular side while the surfaces with domelike topography were on the cytoplasmic side. Hence, this provides a straightforward method to distinguish the two sides of PM without the requirement of high-resolution imaging. Forc...
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PMID: 17358085
PDF is available here.
PDF is available here.
Biophysical Journal (91)9 2006
Abstract
Multiple molecular dynamics simulations of bacterioopsin pulling from its C-terminus show that its alpha-helices unfold individually. In the first metastable state observed in the simulations, helix G is unfolded at its C-terminal segment while the rest of helix G (residues 200-216) is folded and op...
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PMID: 16861280
PDF is available here.
PDF is available here.
Abstract
We show that electronic current passes through bR-containing artificial lipid bilayers in solid "electrode-bilayer-electrode" structures and that the current through the protein is more than four orders of magnitude higher than would be estimated for direct tunneling through 5-nm, water-free peptide...
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PMID: 16731629
PDF is available here.
PDF is available here.
Abstract
We are comparing the structure of bR with the homology model of octopus rhodopsin (octR), which is similar in topology to bR and as highly ordered in its native membranes as bR in purple membranes. Such comparison provides insights for optimization of present octR experimentation both for crystalliz...
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PMID: 16289210
PDF is available here.
PDF is available here.
Journal of Synchrotron Radiation (13)Pt 3 2006
Abstract
X-ray diffraction patterns from a film of oriented purple membranes, which comprise two-dimensional crystals of bacteriorhodopsin (BR) trimers, were recorded with a 1 m-pathlength Guinier-type camera at SPring-8 BL40B2. A well focused X-ray beam and a camera with a high angular resolution of 0.024 d...
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PMID: 16645256
PDF is available here.
PDF is available here.
Acta Crystallographica Section D (62)Pt 4 2006
Abstract
A comparative study of absorption spectroscopy at 100 K has been performed on three-dimensional crystals of bacteriorhodopsin extracted from a lipidic cubic phase and on native purple membrane. A modified microspectrophotometer has been designed which yields absorption data with a high signal-to-noi...
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PMID: 16552137
PDF is available here.
PDF is available here.
Biochemistry (Washington) (45)13 2006
Abstract
These results suggest that motions in the 10s micros correlation regime may be functionally important for the photocycle of bR, and protein-lipid interactions are motionally coupled in this dynamic regime....
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PMID: 16566605
PDF is available here.
PDF is available here.
Abstract
Acetylation of purple membranes (PM) significantly enhances the surface photovoltage that they exhibit, if adsorbed as a monolayer on a solid surface; we suggest that this increase is due to the improved orientation of the PM on the surface.
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PMID: 16538257
PDF is available here.
PDF is available here.
Biophysical Journal (90)6 2006
Abstract
Purple membranes (PM) are two-dimensional crystals formed by bacteriorhodopsin and a variety of lipids. The lipid composition and density in the cytoplasmic (CP) leaflet differ from those of the extracellular (EC) leaflet. A new way of differentiating the two sides of such asymmetric membranes using...
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PMID: 16387758
PDF is available here.
PDF is available here.
Abstract
We extracted and unfolded bacteriorhodopsin monomers from the purple membrane not only from the cytoplasmic side, but also from the extracellular side, and recorded the force extension profiles. This way different pathways through the potential landscape are explored. A map of the 21 most dominant b...
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PMID: 16531236
PDF is available here.
PDF is available here.
Abstract
Abstract
Purple membrane (bacteriorhodopsin) and plant light-harvesting complexes (LHCII) were dried on the optical waveguide sensor with varying thicknesses in a wide range (from 20 to several hundreds of nanometers) and the optical parameters were studied with optical waveguide lightmode spectroscopy. It w...
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PMID: 16213133
PDF is available here.
PDF is available here.
Abstract
Our results support the idea of conformational heterogeneity of the chromophores in the bR in the trimer, suggesting that the three bR subunits in the trimer are not conformationally equal, and therefore, the bisignate CD spectrum of bR in the purple membrane occurs rather due to a superposition of...
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PMID: 16385624
PDF is available here.
PDF is available here.
Abstract
We report several properties of the bacteriorhodopsin mutants P50A (helix B), P91A (helix C) and P186A (helix F). Compared to wild type, strongly perturbed behaviour has been found for these mutants. In the resting state, increased hydroxylamine accessibility and altered Asp-85 pKa and light-dark ad...
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PMID: 16754356
PDF is available here.
PDF is available here.
Biophysical Journal (89)5 2005
Abstract
Our results provide model-free evidence for translational diffusion of confined water in the no-man's land. Potential effects of the confined-water glass transition on nanosecond membrane dynamics were investigated by incoherent elastic neutron scattering experiments. These revealed no differences b...
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PMID: 16055529
PDF is available here.
PDF is available here.
Biophysical Journal (89)5 2005
Abstract
Purple membranes (PM) from halobacteria were hydrated to approximately 0.4 and approximately 0.2 g H(2)O/g of PM and studied by dielectric spectroscopy and differential scanning calorimetry between 120 and 300 K. The dielectric process, attributed to a local (beta) relaxation of the confined superco...
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PMID: 16055533
PDF is available here.
PDF is available here.
Applied Optics (44)30 2005
Abstract
We discuss the relationship between parameters of a bacteriorhodopsin film and the quality of a novelty filter image. For both fixed and moving velocities of the input image, differences in the novelty filter's image as a function of thickness, lifetime of the M state, and molecular concentration ar...
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PMID: 16252649
PDF is available here.
PDF is available here.
Applied Optics (44)26 2005
Abstract
We report experiments with nonlinear-absorption-based, high-contrast, all-optical switching in photochromic bacteriorhodopsin (BR) films. The switching action is accomplished by control of the transmission of a weak probe beam through a BR sample with the help of strong pump beam illumination at 532...
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PMID: 16161665
PDF is available here.
PDF is available here.
Biochimica et Biophysica Acta (1751)2 2005
Abstract
Bacteriorhodopsin (bR) is solubilized efficiently as a monomer by a novel surfactant, a tripod amphiphile (TPA), which permits the formation of purple hexagonal bR crystals under several conditions. The crystals, although small, diffract to 2.5 A resolution using synchrotron radiation. TPA may be us...
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PMID: 15963773
PDF is available here.
PDF is available here.
Abstract
We avoided any separation or modification steps that might modify the lipid composition or even the lipid molecules themselves. Our analysis of integral PM preparations should resolve partially conflicting literature data on the lipid composition of the PM. Using 31P and 1H NMR of detergent-solubili...
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PMID: 15930511
PDF is available here.
PDF is available here.
Biophysical Journal (89)2 2005
Abstract
Purple membranes were adsorbed on freestanding lipid bilayers, termed nano-black lipid membranes (nano-BLMs), suspending the pores of porous alumina substrates with average pore diameters of 280 nm. Nano-BLMs were obtained by first coating the upper surface of the highly ordered porous alumina subst...
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PMID: 15908580
PDF is available here.
PDF is available here.
Journal of Synchrotron Radiation (12)Pt 4 2005
Abstract
Phosphorus is an abundant element in living organisms. It is traceable by its X-ray absorption spectrum which shows a strong white line at its K-edge, comparable with that observed for the L(III) edges of rare earth ions. With purple membrane, the variation of the imaginary part of the anomalous dis...
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PMID: 15968115
PDF is available here.
PDF is available here.
Journal of Physical Chemistry B (109)22 2005
Abstract
Bacteriorhodopsin (bR) trimers naturally form two-dimensional hexagonal crystals in purple membrane (PM), which make it very stable. However, the dnaturation of bR was found to occur during a very narrow pH range when the pH was increased above 12.0, as indicated by inactivation of the photochemical...
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PMID: 16852376
PDF is available here.
PDF is available here.
Abstract
We suggest that this is due to the smaller side chains of the mutant residues liberating space for more water molecules in the proton channel, which would then be able to participate in the proton translocation network. PM thermal dynamics has been shown to be very sensitive to membrane hydration (L...
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PMID: 15688183
PDF is available here.
PDF is available here.
Biochimica et Biophysica Acta (1669)1 2005
Abstract
We found that organic cations such as the amine anesthetics can also regenerate the proton pump in the bR protein. The inhibition of proton transport in the bR protein by the anesthetic cations was elucidated using the wild type, the E204Q and the D96N mutated bRs. The hydrophobic interaction of the...
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PMID: 15842995
PDF is available here.
PDF is available here.
Abstract
The organization of bacteriorhodopsin (bR) within reconstituted purple membranes (RPM) was examined using atomic force microscopy (AFM). Five reconstituted species were examined: RPM 3 (bR/native polar lipids/dimyristoylphosphatidylcholine (DMPC) in a 1:9:14 molar ratio), RPM 4 (bR/native polar lipi...
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PMID: 15748822
PDF is available here.
PDF is available here.
Journal of Molecular Biology (347)3 2005
Abstract
We investigated molecular recognition of antibodies to membrane-antigens and extraction of the antigens out of membranes at the single molecule level. Using dynamic force microscopy imaging and enzyme immunoassay, binding of anti-sendai antibodies to sendai-epitopes genetically fused into bacteriorh...
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PMID: 15755453
PDF is available here.
PDF is available here.
Abstract
We report for the first time, oriented-sample solid-state NMR experiments, specifically polarization inversion spin exchange at the magic angle (PISEMA) and 1H-15N heteronuclear chemical shift correlation (HETCOR), applied to an integral seven-transmembrane protein, bacteriorhodopsin (bR), in natura...
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PMID: 15629653
PDF is available here.
PDF is available here.
Biophysical Journal (88)1 2005
Abstract
These results showed that the conformational changes characterizing structurally the M-intermediate predominantly occur at a later stage of the deprotonation of the Schiff base. Thus, the M-intermediate can be divided into two metastable stages with different physical characteristics....
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PMID: 15516520
PDF is available here.
PDF is available here.
Abstract
We describe a series of experiments that help to characterize the charging phenomenon, which has been termed the Berriman effect. The pattern of buildup and disappearance of the charge pattern has led to several suggestions for how to alleviate the effect. Experiments are described that demonstrate...
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PMID: 19780320
PDF is available here.
PDF is available here.
Abstract
This review provides detailed procedures for the crystallization of membrane proteins via the lipidic cubic phase method. Bacteriorhodopsin-specific, hands-on protocols are given for (i) the preparation of bacteriohordopsin from purple membrane by monomerization in octylglucoside and gel filtration...
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PMID: 15325652
PDF is available here.
PDF is available here.