Bacteriorhodopsin in purple membrane

Other related systems have been studied. These include crocetin" " and rhodopsin and synthetic pigments." The effect of photoselection upon the dichroic ratio in immobilized systems of bacteriorhodopsin in purple membrane have been examined." Photochemical studies of artificial bac-teriorhodopsins have been reported." A streak camera has been used to measure a fluorescence lifetime of less than 2 ps for bacteriorhodopsin at room... 

Molecular Dynamics Simulations of Bacteriorhodopsin in Purple Membrane... 

Ferrand M, Dianoux AJ, Petty W, G. Zaccai G Thermal motions and function of bacteriorhodopsin in purple membranes effects of temperature and hydration studied by neutron scattering. Proc. Natl. Acad Sci. U. S. A 1993, 90 9668-9672. 

Fitter J, Verclas SAW, Lechner RE, Seelert H, Dencher NA Function and picosecond dynamics of bacteriorhodopsin in purple membrane at different Upidation and hydration. 

Uruga, T., Hamanaka, T., Kito, Y, Uchida, 1., Nishimura, S., and Mashimo, T, Effects of volatile anesthetics on bacteriorhodopsin in purple membrane, Halobacterium halobium cells and reconstituted vesicles, Biophys. Chem., 41,2, 157-168, 1991. 

Lee, K.H., McIntosh, A.R., and Boucher, F., The interaction between halogenated anaesthetics and bacteriorhodopsin in purple membranes as examined by intrinsic ultraviolet fluorescence, Biochem. Cell Biol, 69, 2-3, 178-184,1991. 

Lin, C.T., Chyan, Y.G., Kresheck, G.C., Bitting, H.C., Jr., and El-Sayed, M.A., Interaction of dibucaine HCl local anesthetics with bacteriorhodopsin in purple membrane a spectroscopic study,... 

Bromley, KM., Patil, A.J., Seddon, A. M., Booth, P. and Mann, S. (2007) Bio-functional mesolamellar nanocomposite based on inorganic/ polymer intercalation in purple membrane (Bacteriorhodopsin) films. Advanced Materials, 19, 2433—2438. 

Neutron diffraction of samples with added deuterated water [130], as well as hydrogen exchange studies [118], suggest that no aqueous channels exist between the protein molecules in purple membranes, or between the helices, i.e., the lipids completely fill the spaces. As expected from the crystalline structure and the relatively low lipid/protein ratio, the packing of protein in purple membrane is quite rigid, and the mobility of the protein in the lattice appears low, as determined by flash dichroism [131,132]. On the other hand, bacteriorhodopsin incorporated into liposomes at high lipid/protein ratios exists as a monomeric molecule [133], and shows rapid rotation by this criterion (relaxation time 15 /us) above the phase... 

Varga K, Aslimovska L, Watts A (2008) Advances towards resonance assignments for uniformly - C-13, N-15 enriched bacteriorhodopsin at 18.8 T in purple membranes. J Biomol NMR 41 1 ... 

We will illustrate the coupling of protein and water dynamics using results of MD simulations of several systems, including native and MG states of human a-lactalbumin (HaLA) in aqueous solution [5], ribonuclease A (RNase) in dry and hydrated powders and glycerol solution [6,7], maltose-binding protein (MBP) in a hydrated powder [8], and bacteriorhodopsin (BR) in purple membrane (PM) stacks [9,10]. Our choice of specific systems has generally been made based on the availability of experimental data to which the simulation results can be closely compared. We have accordingly set up the systems so that the simulations are very similar to the experiments, both in terms of sample composition and thermodynamic state points (i.e., temperature and pressure). 

Table 3. Assigned C chemical shifts for [3- C]Ala and [l- C]Val residues in [3- C]Ala-, [l- C]Val-labeled bacteriorhodopsin from purple membrane...

BACKBONE DYNAMICS AND STRUCTURES IN THE INTERFACIAL DOMAINS OF BACTERIORHODOPSIN FROM PURPLE MEMBRANE... 

M. Kamihira, A. Watts, Functionally relevant coupled dynamic profile of bacteriorhodopsin and lipids in purple membranes. Biochemistry 45 (2006) 4304—4313. 

Olle Edholm, Oliver Berger, and Fritz Jahnig. Structure and fluctuations of bacteriorhodopsin in the purple membrane. J. Mol. Biol., 250 94 111, 1995. 

ITowever, membrane proteins can also be distributed in nonrandom ways across the surface of a membrane. This can occur for several reasons. Some proteins must interact intimately with certain other proteins, forming multisubunit complexes that perform specific functions in the membrane. A few integral membrane proteins are known to self-associate in the membrane, forming large multimeric clusters. Bacteriorhodopsin, a light-driven proton pump protein, forms such clusters, known as purple patches, in the membranes of Halobacterium halobium (Eigure 9.9). The bacteriorhodopsin protein in these purple patches forms highly ordered, two-dimensional crystals. 

Ethanol and choline glycerolipids were isolated from calf brain and beef heart lipids by PTLC using silica gel H plates. Pure ethanol amine and choline plasmalogens were obtained with a yield of 80% [74]. Four phosphohpid components in the purple membrane (Bacteriorhodopsin) of Halobacterium halobium were isolated and identified by PTLC. Separated phosphohpids were add-hydrolyzed and further analyzed by GC. Silica gel G pates were used to fractionate alkylglycerol according to the number of carbon atoms in the aliphatic moiety [24]. Sterol esters, wax esters, free sterols, and polar lipids in dogskin hpids were separated by PTLC. The fatty acid composition of each group was determined by GC. 

Indeed, hydrophilic N- or C-terminal ends and loop domains of these membrane proteins exposed to aqueous phases are able to undergo rapid or intermediate motional fluctuations, respectively, as shown in the 3D pictures of transmembrane (TM) moieties of bacteriorhodopsin (bR) as a typical membrane protein in the purple membrane (PM) of Halobacterium salinarum.176 178 Structural information about protein surfaces, including the interhelical loops and N- and C-terminal ends, is completely missing from X-ray data. It is also conceivable that such pictures should be further modified, when membrane proteins in biologically active states are not always present as oligomers such as dimer or trimer as in 2D or 3D crystals but as monomers in lipid bilayers. 

The CP MAS NMR spectroscopy has been also extensively used for studies of proteins containing retinylidene chromophore like proteorhodopsin or bacteriorhodopsin. Bacteriorhodopsin is a protein component of purple membrane of Halobacterium salinarium.71 7 This protein contains 248 amino acids residues, forming a 7-helix bundle and a retinal chromophore covalently bound to Lys-216 via a Schiff base linkage. It is a light-driven proton pump that translocates protons from the inside to the outside of the cell. After photoisomerization of retinal, the reaction cycle is described by several intermediate states (J, K, L, M, N, O). Between L and M intermediate states, a proton transfer takes place from the protonated Schiff base to the anionic Asp85 at the central part of the protein. In the M and/or N intermediate states, the global conformational changes of the protein backbone take place. 

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