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Topic: Bacteriorhodopsin

	Bacteriorhodopsin - Wikipedia, the free encyclopedia
		Bacteriorhodopsin is an integral membrane protein usually found in two-dimensional crystalline patches known as "purple membrane", which can occupy up to nearly 50% of the surface area of the archaeal cell.
		The three-dimensional tertiary structure of bacteriorhodopsin resembles that of vertebrate rhodopsins, the pigments that sense light in the retina.
		Both rhodopsin and bacteriorhodopsin belong to the 7TM receptor family of proteins, but rhodopsin is a G protein coupled receptor and bacteriorhodopsin is not.
	en.wikipedia.org /wiki/Bacteriorhodopsin (427 words)

	Fun with Bacteriorhodopsin
		Bacteriorhodopsin became an ideal choice for study because of its naturally high levels in the plasma membrane of these halophilic archaeans under conditions of low oxygen tension and high light.
		The position of the covalent attachment between the retinal and the Lys216 residue of the bacteriorhodopsin is shown here with the lysine residue in red and the retinal in white.
		determined the structure (PDB code 1CWQ) of a late M intermediate of wild-type bacteriorhodopsin at 2.25 Å resolution [6] and observed a net of water molecules involved in moving a proton from the donor group Asp96 towards the Schiff base.
	www.arches.uga.edu /~bgiri/bcmb8010 (2279 words)

	BME 220 Homework 1: Making Pictures
		Bacteriorhodopsin is a protein in some archaea that detects light using a small chromophore (light-absorbing group) named retinal that is embedded in the bacteriorhodopsin.
		Bacteriorhodopsin is a light-driven proton pump used for energy conversion, converting light to a proton gradient.
		Bacteriorhodopsin is structurally similar to the G-protein-linked receptors, but since it is not coupled to a G-protein it is not actually a type of G-protein-linked receptor.
	www.soe.ucsc.edu /~dmng/bme220hw1 (1687 words)

	Bacteriorhodopsin: Pumping Ions
		Bacteriorhodopsin (BR) is a membrane-embedded protein that can actively "pump" ions from one side of the membrane to the other, against an electrochemical gradient.
		Proteins embedded in the membranes are responsible for all forms of intercell signaling, sensing of external stimuli, and the transport of molecules and ions.
		Bacteriorhodopsin has been called the "hydrogen atom of membrane proteins" because it is a relatively small, simple protein, extracted from Halobacterium salinarum, that can provide valuable insights into the principles governing membrane-protein function.
	www-als.lbl.gov /als/science/sci_archive/rhodopsin.html (885 words)

	Method and preparation for the photochromic marking and/or for securing the authenticity of objects - Patent 6616964
		The term "chromophoric variants of bacteriorhodopsin" is to be understood as meaning in particular bacteriorhodopsin variants which differ from the wild-type by the removal or exchange of the chromophoric retinylidene group for another molecule, in particular for "retinal analogs".
		Bacteriorhodopsin whose maximum absorption is at 570 nm (B state) relaxes in the dark slowly with a half-life of about 10 to 20 minutes partly to a state of 548 nm maximum absorption, the "D state".
		Bacteriorhodopsin variants which have a reduced or absent light/dark adaptation may be obtained by using retinal analogs or by bacteriorhodopsin variants having a modified amino acid sequence.
	www.freepatentsonline.com /6616964.html (8093 words)

	Bacteriorhodopsin
		Bacteriorhodopsin is a trans-membrane protein found in the cellular membrane of Halobacterium salinarium, which functions as a light-driven proton pump.
		It is proposed to utilize a combination of ab initio quantum mechanical and molecular mechanical approaches to model (1) the initial retinal photoisomerization and (2) the proton transfer stages in the bacteriorhodopsin photocycle.
		In modelling the bacteriorhodopsin photocycle, a combination of the ab initio quantum mechanical and molecular mechanical methods will be used for the first time to do direct dynamical simulations.
	www.ks.uiuc.edu /Research/bio_ener/bR (523 words)

	21st-"Chall.Hong.Intelligent.Materials
		Bacteriorhodopsin is a purple-colored pigment occurring in natural abundance in the cell membrane of Halobacterium halobium [3].
		In the case of the purple membrane, the membrane is the "dam" and bacteriorhodopsin is the "pump" that utilizes solar energy to move protons across the membrane, resulting in a difference in proton levels (a proton is the nucleus of a hydrogen atom).
		The use of a bacteriorhodopsin mutant as a reversible holographic medium (Paper by Norbert Hampp [9] in this Symposium) and the use of chemically modified bacteriorhodopsin for construction of "Biochrom" films (Papers by N. Vsevolodov and by A. Druzhko in this Symposium) are existing successful examples.
	www.vxm.com /21R.58.html (3058 words)

	Light-induced hydrolysis and rebinding of nonisomerizable bacteriorhodopsin pigment Biophysical Journal - Find Articles
		Light-induced hydrolysis and rebinding of nonisomerizable bacteriorhodopsin pigment
		ABSTRACT Bacteriorhodopsin (bR) is characterized by a retinal-protein protonated Schiff base covalent bond, which is stable for light absorption.
		Lewis, A. The molecular mechanism of excitation in visual transduction and bacteriorhodopsin.
	www.findarticles.com /p/articles/mi_qa3938/is_200205/ai_n9026810 (610 words)

	PDB Molecule of the Month: Bacteriorhodopsin (Site not responding. Last check: 2007-10-21)
		Bacteriorhodopsin is a compact molecular machine that pumps protons across a membrane powered by green sunlight.
		Bacteriorhodopsin, shown here from PDB entry 1fbb, is composed of three protein chains.
		In bacteriorhodopsin, this is a change from a straight form to a bent form, as shown on a later page.
	pdbdev.sdsc.edu:48346 /pdb/molecules/pdb27_1.html (392 words)

	Binding of Calcium Ions to Bacteriorhodopsin -- Váró et al. 76 (6): 3219 -- Biophysical Journal
		H is plotted for wild-type bacteriorhodopsin and the E194Q, E204Q, E194/E204Q, and D36N/D38N/D102N mutants.
		Existence of a proton transfer chain in bacteriorhodopsin: participation of Glu-194 in the release of protons to the extracellular surface.
		Importance of bound divalent cations to the tyrosine deprotonation during the photocycle of bacteriorhodopsin.
	www.biophysj.org /cgi/content/full/76/6/3219 (4479 words)

	NAI News Article: Terrestrial Powerhouses (Site not responding. Last check: 2007-10-21)
		Bacteriorhodopsin is an intensely purple-colored protein found in microbes that live in extreme environments such as salt marshes and salt lakes.
		In this way, bacteriorhodopsin is a protein powerhouse that turns on in times of famine, changing color from purple to yellow as it absorbs light.
		Bacteriorhodopsin is also an attractive material for all-optical 'light' computers because of its two stable protein forms, one purple and one yellow.
	nai.arc.nasa.gov /news_stories/news_print.cfm?ID=216 (1014 words)

	Faculty Profile for Janos K. Lanyi
		The results indicate that after absorption of light the all-trans retinal in bacteriorhodopsin is isomerized to 13-cis.
		Transport Mechanism of Bacteriorhodopsin from Crystal Structures of the K, L, M1, M2 and M2’ Intermediates of the Photocycle.
		Crystallographic Structures of the M and N Intermediates of Bacteriorhodopsin: Assembly of a Hydrogen-bonded Chain of Water Molecules Between Asp-96 and the Retinal Schiff base.
	www.faculty.uci.edu /profile.cfm?faculty_id=2216 (805 words)

	Bacteriorhodopsin
		Bacteriorhodopsin (bR) is a proton pump located in the cytoplasmic membrane of purple bacteria.
		N Grigorieff et al, Electron-crystallographic refinement of the structure of bacteriorhodopsin, J. Mol.
		JK Lanyi, Understanding structure and function in the light-driven proton pump bacteriorhodopsin, J. Struct.
	www.biologie.uni-hamburg.de /lehre/bza/kanal/transp/rhod/e2brdstext.htm (698 words)

	How Environment Supports a State: Molecular Dynamics Simulations of Two States in Bacteriorhodopsin Suggest Lipid and ...
		In the top figure, a water molecule is shown as red (oxygen) and white beads (hydrogen), a lipid tail is shown as a thread, phosphate in the lipid headgroup is shown as a blue bead, sodium is shown as a green bead, and chloride is shown as a purple bead.
		Elucidation of the nature of the conformational changes of the EF-interhelical loop in bacteriorhodopsin and of the helix VIII on the cytoplasmic surface of bovine rhodopsin: a time-resolved fluorescence depolarization study.
		Crystallographic intermediates of structures of the M and N bacteriorhodopsin: assembly of a hydrogen-bonded chain of water molecules between Asp-96 and the retinal Schiff base.
	www.biophysj.org /cgi/content/full/87/1/129 (7934 words)

	[No title]
		A schlieren apparatus using a bacteriorhodopsin film as an adaptive image grid with white light illumination is demonstrated for the first time.
		Though the general spectral properties of bacteriorhodopsin films are well established, a presentation of relevant optical behavior using the common low-cost sources and filters used here is of value, since a previous effort using different optics reported failure[5].
		The bacteriorhodopsin film was obtained from Bend Research and had a nominal optical density of 2.8 at 570 nm (absorbance of 6.5).
	www.physics.ucf.edu /~rep/schlieren (2548 words)

	Today@UCI: Press Releases:
		Although it is found in a highly specialized, salt marsh-dwelling bacteria called Halobacterium salinarum, bacteriorhodopsin’s structure and activity is a blueprint for other cell receptors, enzymes and energy-producing proteins.
		The researchers, who last year used X-rays to create the most accurate picture ever of the bacteriorhodopsin protein, used the same technique to create three-dimensional pictures of the protein as it went through the pumping motion of generating energy.
		On the left, in purple, bacteriorhodopsin is in its resting state.
	today.uci.edu /news/release_detail.asp?key=785 (781 words)

	Bacteriorhodoopsin Memory
		Bacteriorhodopsin is a light-harvesting protein from bacteria that live in salt marshes that has shown some promise as a feasible optical data storage.
		Bacteriorhodopsin is a protein found in the purple membranes of several species of bacteria, most notably Halobacterium halobium.
		Bacteriorhodopsin, after being initially exposed to light (in our case a laser beam), will change to between photoisomers during the main photochemical event when it absorbs energy from a second laser beam.
	www.cem.msu.edu /~cem181h/projects/96/memory/index.html (2069 words)

	Science News Online (3/8/97): Bacteria give new meaning to 'computer bug'
		Bacteriorhodopsin is an attractive material for optical computers because it exists in two stable forms, one purple and one yellow.
		Several groups have used bacteriorhodopsin as computer memory and as the light-sensitive element in artificial retinas.
		That varying intensity altered the relative concentrations of the purple and yellow forms of bacteriorhodopsin.
	www.sciencenews.org /sn_arc97/3_8_97/fob2.htm (417 words)

	Memory of the future: two directions
		This bacterium lives in salt bogs where the temperature can reach +150 °C. When a level of oxygen contents is so low in the ambient that to obtain power breathing (oxidation) is not enough, it uses protein for photosynthesis.
		Bacteriorhodopsin was chosen because a photocycle (a sequence of structural changes undergone by a molecule when reacting with light) makes this molecule an ideal logically storing element of "and" type or a type of a switch from one condition into another (trigger).
		Another important feature of the bacteriorhodopsin is that these both states have different absorption spectra.
	www.digit-life.com /articles/memorytwodirections (2735 words)

	Janos Lanyi
		In bacteriorhodopsin, the reversible loss of a proton during the photocycle is thought to be the central event in the transport cycle.
		Structures of Aspartic Acid-96 in the L and N Intermediates of Bacteriorhodopsin: Analysis by Fourier Transform Infrared Spectroscopy.
		Photoreaction of the N Intermediate of Bacteriorhodopsin and its Relationship to the Decay Kinetics of the M Intermediate.
	www.ucihs.uci.edu /microbio/facultyResearch/faculty/lanyi.html (2323 words)

	Learn more about the University of Miami's Dept of Physiology & Biophysics
		Bacteriorhodopsin is structurally homologous to the G protein-coupled receptor family and is the best system available for structure-function studies of this class of protein.
		Mutagenic approaches have revealed a number of the critical amino acids involved in bacteriorhodopsin function, but that analysis is incomplete.
		This is an excellent system for thermodynamic characterization of bacteriorhodopsin conformational transitions, and structural studies on isolated intermediate species.
	pirate.shu.edu /~turnerge (642 words)

	Unraveling Bacteriorhodopsin Biophysical Journal - Find Articles
		Furthermore, careful analysis of the recorded force during pulling revealed a discontinuous release, in which each peak in the pulling force can be attributed to single or pairs of the seven transmembrane α-helices that form a single bacteriorhodopsin.
		Not only the complete disruption of one or two of the α-helices can be observed but new force peaks are found about halfway of two of the helices.
		The authors argue that the ability to identify these new unfolding pathways is a result of an effective increase of the pulling rate as the tip moves upward during the oscillation.
	www.findarticles.com /p/articles/mi_qa3938/is_200502/ai_n10298203 (842 words)

	NAI: News Stories (Site not responding. Last check: 2007-10-21)
		"Ball and Stick" molecular structure of the transmembrane protein bacteriorhodopsin: Bacteriorhodopsin is quite similar to rhodopsin, the light-detecting pigment found in the retinas of vertebrates (like humans).
		Simplified schematic of how bacteriorhodopsin works: Incoming light is converted to create a charge (pH) difference across the cell membrane (symbolized by darker green).
		NASA researchers in the Intelligent Physics group are studying the use of bacteriorhodopsin as a real-time holographic material for holographic optical data storage.
	nai.arc.nasa.gov /news_stories/news_detail.cfm?article=old/powerhouses.htm (1127 words)

	Bacteriorhodopsin Photocycle
		Bacteriorhodopsin is a photochemically active protein found in the purple membrane of the bacteria Halobacterium salinarium, which was known as Halobacterium halobium.
		This network exhibits changes most often in the bR to L transformation, which would be the first step in writing to a block of bacteriorhodopsin memory.
		In the K intermediate, a H-bonding change of the peptide C to O double bond of a valine residue, called Val49, occurs.
	www.cem.msu.edu /~cem181h/projects/96/memory/photocycle.html (892 words)

	New role for bacteriorhodopsin (Site not responding. Last check: 2007-10-21)
		The light energy of the bacteriorhodopsin can be converted to electrical energy, which is the key to its utility.
		Naturally occurring bacteriorhodopsin shifts from purple to yellow and back almost instantaneously, but Dr. Needleman is genetically engineering mutants that will maintain the color changes for longer periods of time, depending on the proposed use.
		The mutants that retain the color indefinitely would be important for computer memories while those that change back and forth would be effective as optical switches and other devices.
	www.med.wayne.edu /Scribe/scribe97-98/scribes98/role_for_bacterio.htm (381 words)

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