Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| specific interactions between four molybdenum-binding proteins contribute to mo-dependent gene regulation in rhodobacter capsulatus. | the phototrophic purple bacterium rhodobacter capsulatus encodes two transcriptional regulators, mopa and mopb, with partially overlapping and specific functions in molybdate-dependent gene regulation. both mopa and mopb consist of an n-terminal dna-binding helix-turn-helix domain and a c-terminal molybdate-binding di-mop domain. they formed homodimers as apo-proteins and in the molybdate-bound state as shown by yeast two-hybrid (y2h) studies, glutaraldehyde cross-linking, gel filtration chromat ... | 2009 | 19502397 |
| two-photon excitation spectroscopy of carotenoid-containing and carotenoid-depleted lh2 complexes from purple bacteria. | we applied two-photon fluorescence excitation spectroscopy to lh2 complex from purple bacteria allochromatium minutissimum and rhodobacter sphaeroides . bacteriochlorophyll fluorescence was measured under two-photon excitation of the samples within the 1200-1500 nm region. spectra were obtained for both carotenoid-containing and -depleted complexes of each bacterium to allow their direct comparison. the depletion of carotenoids did not alter the two-photon excitation spectra of either bacteria. ... | 2009 | 19650635 |
| the role of arginine-127 at the proximal no-binding site in determining the electronic structure and function of 5-coordinate no-heme in cytochrome c' of rhodobacter sphaeroides. | cytochrome c' is a heme protein from a denitrifying variant of rhodobacter sphaeroides which may serve to store and transport metabolic no while protecting against no toxicity. its heme site bears resemblance through its 5-coordinate no-binding capability to the regulatory site in soluble guanylate cyclase. a conserved arginine (arg-127) abuts the 5-coordinate no-heme binding site, and the alanine mutant r127a provided insight into the role of the arg-127 in establishing the electronic structure ... | 2009 | 19685879 |
| energetics of bacterial photosynthesis. | we report the results of extensive numerical simulations and theoretical calculations of electronic transitions in the reaction center of rhodobacter sphaeroides photosynthetic bacterium. the energetics and kinetics of five electronic transitions related to the kinetic scheme of primary charge separation have been analyzed and compared to experimental observations. nonergodic formulation of the reaction kinetics is required for the calculation of the rates due to a severe breakdown of the system ... | 2009 | 19691308 |
| spectral diffusion and electron-phonon coupling of the b800 bchl a molecules in lh2 complexes from three different species of purple bacteria. | we have investigated the spectral diffusion and the electron-phonon coupling of b800 bacteriochlorophyll a molecules in the peripheral light-harvesting complex lh2 for three different species of purple bacteria, rhodobacter sphaeroides, rhodospirillum molischianum, and rhodopseudomonas acidophila. we come to the conclusion that b800 binding pockets for rhodobacter sphaeroides and rhodopseudomonas acidophila are rather similar with respect to the polarity of the protein environment but that the p ... | 2009 | 19883604 |
| identification of the intermediate charge-separated state p+betal- in a leucine m214 to histidine mutant of the rhodobacter sphaeroides reaction center using femtosecond midinfrared spectroscopy. | energy and electron transfer in a leu m214 to his (lm214h) mutant of the rhodobacter sphaeroides reaction center (rc) were investigated by applying time-resolved visible pump/midinfrared probe spectroscopy at room temperature. this mutant replacement of the leu at position m214 resulted in the incorporation of a bacteriochlorophyll (bchl) in place of the native bacteriopheophytin in the l-branch of cofactors (denoted betal). purified lm214h rcs were excited at 600 nm (unselective excitation), at ... | 2009 | 19527655 |
| [degradation of dichlorvos by rhodobacter sphaeroides]. | rhodobacter sphaeroides possesses an extensive range of energy acquiring mechanisms including photosynthesis, lithotrophy, aerobic and anaerobic respiration. it can produce 5-aminolevulinic acid, coq10, carotenoids, hydrogen, etc. by fermentation. a rhodobacter sphaeroides strain was isolated, designated as ebl0706, from soil. the degradation of dichlorvos (ddvp) by the rhodobacter sphaeroides was investigated. 98% of ddvp could be degraded in water solution in 12 h when 5 x 10(8) cfu/ml rhodoba ... | 2009 | 19545029 |
| differential charge polarization of axial histidines in bacterial reaction centers balances the asymmetry of the special pair. | in photosynthesis, light energy is transformed into chemical energy that sustains most forms of life on earth. solid-state nmr spectroscopy in conjunction with density functional theory modeling can resolve electronic structure down to the atomic level in large membrane proteins. in this work, we have used this technique to address the mechanisms underlying the photochemical reactivity of the special pair in the bacterial reaction center. for charge separation, the electrostatics is important, a ... | 2009 | 19548676 |
| export or recombination of charges in reaction centers in intact cells of photosynthetic bacteria. | the kinetics and thermodynamics of forward and reverse electron transfer around the reaction center of purple bacterium rhodobacter sphaeroides were studied in vivo by flash-excited delayed fluorescence, prompt fluorescence (induction) and kinetic difference absorption. by protection of the photomultiplier from intense bacteriochlorophyll prompt fluorescence evoked by laser excitation, the time resolution of the fluorometer was reduced typically 10 micros. two precursor states of the delayed flu ... | 2009 | 19555655 |
| expression and regulation of ribulose 1,5-bisphosphate carboxylase/oxygenase genes in mycobacterium sp. strain jc1 dsm 3803. | ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) is the key enzyme of the calvin reductive pentose phosphate cycle. two sets of structural genes (cbbls-1 and -2) for form i rubisco have been previously identified in the mycobacterium sp. strain jc1, which is able to grow on carbon monoxide (co) or methanol as sole sources of carbon and energy. northern blot and reverse transcriptase pcr showed that the cbbls-1 and -2 genes are expressed in cells grown on either carbon monoxide (co) or m ... | 2009 | 19557347 |
| arg-85 and thr-430 in murine 5-aminolevulinate synthase coordinate acyl-coa-binding and contribute to substrate specificity. | 5-aminolevulinate synthase (alas) controls the rate-limiting step of heme biosynthesis in mammals by catalyzing the condensation of succinyl-coenzyme a and glycine to produce 5-aminolevulinate, coenzyme-a (coa), and carbon dioxide. alas is a member of the alpha-oxoamine synthase family of pyridoxal 5'-phosphate (plp)-dependent enzymes and shares high degree of structural similarity and reaction mechanism with the other members of the family. the x-ray crystal structure of alas from rhodobacter c ... | 2009 | 19562746 |
| extracellular iron biomineralization by photoautotrophic iron-oxidizing bacteria. | iron oxidation at neutral ph by the phototrophic anaerobic iron-oxidizing bacterium rhodobacter sp. strain sw2 leads to the formation of iron-rich minerals. these minerals consist mainly of nano-goethite (alpha-feooh), which precipitates exclusively outside cells, mostly on polymer fibers emerging from the cells. scanning transmission x-ray microscopy analyses performed at the c k-edge suggest that these fibers are composed of a mixture of lipids and polysaccharides or of lipopolysaccharides. th ... | 2009 | 19592528 |
| internal electrostatic control of the primary charge separation and recombination in reaction centers from rhodobacter sphaeroides revealed by femtosecond transient absorption. | we report the observation of two conformational states of closed rcs from rhodobacter sphaeroides characterized by different p(+)h(a)(-) --> ph(a) charge recombination lifetimes, one of which is of subnanosecond value (700 +/- 200 ps). these states are also characterized by different primary charge separation lifetimes. it is proposed that the distinct conformations are related to two protonation states either of reduced secondary electron acceptor, q(a)(-), or of a titratable amino acid residue ... | 2009 | 19603803 |
| a cryptochrome-like protein is involved in the regulation of photosynthesis genes in rhodobacter sphaeroides. | blue light receptors belonging to the cryptochrome/photolyase family are found in all kingdoms of life. the functions of photolyases in repair of uv-damaged dna as well as of cryptochromes in the light-dependent regulation of photomorphogenetic processes and in the circadian clock in plants and animals are well analysed. in prokaryotes, the only role of members of this protein family that could be demonstrated is dna repair. recently, we identified a gene for a cryptochrome-like protein (cryb) i ... | 2009 | 19878455 |
| exploration of the hydrogen producing potential of rhodobacter capsulatus chemostat cultures: the application of deceleration-stat and gradient-stat methodology. | in this work, the dependency of the volumetric hydrogen production rate of ammonium-limited rhodobacter capsulatus chemostat cultures on their imposed biomass concentration and dilution rate was investigated. a deceleration-stat experiment was performed by lowering the dilution rate from 1.0 d(-1) to zero aimed at a constant biomass concentration of 4.0 g l(-1) at constant incident light intensity. the results displayed a maximal volumetric hydrogen production rate of 0.6 mmol m(-3) s(-1), well ... | 2009 | 19626702 |
| stark realities. | electric fields affect any process or transition that involves the movement of charge. stark spectroscopy is a general term describing the study of spectral changes in the presence of electric fields, and it has proven to be a broadly useful approach for characterizing the change in dipole moment and polarizability for electronic and vibrational transitions. this article focuses primarily on the evolution of the approach and interconnected applications in diverse fields from our laboratory and p ... | 2009 | 19708160 |
| membrane curvature induced by aggregates of lh2s and monomeric lh1s. | the photosynthetic apparatus of purple bacteria is contained within organelles called chromatophores, which form as extensions of the cytoplasmic membrane. the shape of these chromatophores can be spherical (as in rhodobacter sphaeroides), lamellar (as in rhodopseudomonas acidophila and phaeospirillum molischianum), or tubular (as in certain rb. sphaeroides mutants). chromatophore shape is thought to be influenced by the integral membrane proteins light harvesting complexes i and ii (lh1 and lh2 ... | 2009 | 19948127 |
| rhodobacter capsulatus catalyzes light-dependent fe(ii) oxidation under anaerobic conditions as a potential detoxification mechanism. | diverse bacteria are known to oxidize millimolar concentrations of ferrous iron [fe(ii)] under anaerobic conditions, both phototrophically and chemotrophically. yet whether they can do this under conditions that are relevant to natural systems is understood less well. in this study, we tested how light, fe(ii) speciation, ph, and salinity affected the rate of fe(ii) oxidation by rhodobacter capsulatus sb1003. although r. capsulatus cannot grow photoautotrophically on fe(ii), it oxidizes fe(ii) a ... | 2009 | 19717624 |
| spin labeling epr. | site-directed spin labeling in combination with electron paramagnetic resonance spectroscopy has emerged as an efficient tool to elucidate the structure and conformational dynamics of biomolecules under native-like conditions. this article summarizes the basics as well as recent progress of site-directed spin labeling. continuous wave epr spectra analyses and pulse epr techniques are reviewed with special emphasis on applications to the sensory rhodopsin-transducer complex mediating the photopho ... | 2009 | 19728138 |
| modification of a french pressure cell to improve microbial cell disruption. | a procedure for modification of the valve stem of a 40 k french pressure cell is described. the modification should be done by a machinist and requires a metalworking lathe. after modification of the valve stem, a torlon 4203 plastic ball is used between the valve stem and valve seat to control the pressure within the cell. the torlon plastic ball is a key component needed to obtain the high pressures required for efficient disruption of microbial cells. | 2009 | 19731071 |
| spectroscopic studies of the appa bluf domain from rhodobacter sphaeroides: addressing movement of tryptophan 104 in the signaling state. | previous crystallographic studies of the appa bluf domain indicated that trp104 is capable of undertaking alternate conformations depending on the length of the bluf domain. a bluf domain containing a c-terminal deletion (appa1-126) reveals that trp104 is partially solvent exposed while a bluf domain containing a slightly longer carboxyl terminal region (appa17-133) shows that trp104 is deeply buried. this observation has led to a model proposing that trp104 moves from a deeply buried position i ... | 2009 | 19746968 |
| features of structural organization and expression regulation of malate dehydrogenase isoforms from rhodobacter sphaeroides strain 2r. | two isoforms of malate dehydrogenase (mdh), dimeric and tetrameric, have been found in the purple non-sulfur bacterium rhodobacter sphaeroides strain 2r, devoid of the glyoxylate shunt, which assimilate acetate via the citramalate cycle. inhibitory analysis showed that the 74-kda protein is involved in tricarboxylic acid cycle, while the 148-kda mdh takes part in the citramalate pathway. a single gene encoding synthesis of the isologous subunits of the mdh isoforms was found during molecular-bio ... | 2009 | 19747101 |
| the cobinamide amidohydrolase (cobyric acid-forming) cbiz enzyme: a critical activity of the cobamide remodelling system of rhodobacter sphaeroides. | the chemical structures of cobamides [cobalamin (cbl)-like compounds] are the same, except for the lower ligand, which in adenosylcobalamin (adocbl) is 5,6-dimethylbenzimidazole, and in adenosylpseudocobalamin (adopseudocbl) is adenine. why the lower ligand of cobamides varies and what the mechanism of lower ligand replacement is are long-standing questions in the field of b(12) biosynthesis. work reported here uncovers the strategy used by the photosynthetic alpha-proteobacterium rhodobacter sp ... | 2009 | 19889098 |
| m234glu is a component of the proton sponge in the reaction center from photosynthetic bacteria. | bacterial reaction centers use light energy to couple the uptake of protons to the successive semi-reduction of two quinones, namely q(a) and q(b). these molecules are situated symmetrically in regard to a non-heme iron atom. four histidines and one glutamic acid, m234glu, constitute the five ligands of this atom. by flash-induced absorption spectroscopy and delayed fluorescence we have studied in the m234eh and m234el variants the role played by this acidic residue on the energetic balance betw ... | 2009 | 19632193 |
| a glycophorin a-like framework for the dimerization of photosynthetic core complexes. | the core complex in photosynthetic bacteria plays a central role in photosynthesis. this molecular assembly is composed of two protein complexes, viz., the light-harvesting complex i (lh1), which absorbs sunlight by means of the protein-bound bacteriochlorophylls, and the reaction center (rc), which uses the light-excitation energy absorbed by the lh complexes to produce a transmembrane (tm) charge gradient, subsequently employed for energy conversion. in rhodobacter (rba.) sphaeroides, the core ... | 2009 | 19891482 |
| characteristics of light-harvesting complex ii mutant of rhodobacter sphaeroides with alterations at the transmembrane helices of beta-subunit. | the peripheral light-harvesting complex ii (lhii) is an important component of the photosynthetic apparatus of rhodobacter sphaeroides. in this study, genetic, biochemical, and spectroscopic approaches were applied to investigate the spectral properties and functions of lhii in which two amino acid residues phe32 and leu42 in the transmembrane helix domain of pucb-encoded beta-apoprotein were replaced by leu and pro. the mutated lhii complex showed blue shift of absorbance peaks in the near infr ... | 2009 | 19747103 |
| theoretical examination of quantum coherence in a photosynthetic system at physiological temperature. | the observation of long-lived electronic coherence in a photosynthetic pigment-protein complex, the fenna-matthews-olson (fmo) complex, is suggestive that quantum coherence might play a significant role in achieving the remarkable efficiency of photosynthetic electronic energy transfer (eet), although the data were acquired at cryogenic temperature [engel gs, et al. (2007) evidence for wavelike energy transfer through quantum coherence in photosynthetic systems. nature 446:782-786]. in this pape ... | 2009 | 19815512 |
| proton environment of reduced rieske iron-sulfur cluster probed by two-dimensional eseem spectroscopy. | the proton environment of the reduced [2fe-2s] cluster in the water-soluble head domain of the rieske iron-sulfur protein (isf) from the cytochrome bc(1) complex of rhodobacter sphaeroides has been studied by orientation-selected x-band 2d eseem. the 2d spectra show multiple cross-peaks from protons, with considerable overlap. samples in which (1)h(2)o water was replaced by (2)h(2)o were used to determine which of the observed peaks belong to exchangeable protons, likely involved in hydrogen bon ... | 2009 | 19099453 |
| proteomic analysis and identification of the structural and regulatory proteins of the rhodobacter capsulatus gene transfer agent. | the gene transfer agent of rhodobacter capsulatus (gta) is a unique phage-like particle that exchanges genetic information between members of this same species of bacterium. besides being an excellent tool for genetic mapping, the gta has a number of advantages for biotechnological and nanoengineering purposes. to facilitate the gta purification and identify the proteins involved in gta expression, assembly and regulation, in the present work we construct and transform into r. capsulatus y262 a ... | 2009 | 19105630 |
| in vivo analysis of cobinamide salvaging in rhodobacter sphaeroides strain 2.4.1. | the genome of rhodobacter sphaeroides encodes the components of two distinct pathways for salvaging cobinamide (cbi), a precursor of adenosylcobalamin (adocbl, coenzyme b(12)). one pathway, conserved among bacteria, depends on a bifunctional kinase/guanylyltransferase (cobp) enzyme to convert adenosylcobinamide (adocbi) to adocbi-phosphate (adocbi-p), an intermediate in de novo adocbl biosynthesis. the other pathway, of archaeal origin, depends on an adocbi amidohydrolase (cbiz) enzyme to genera ... | 2009 | 19376876 |
| comparative metagenomics of daphnia symbionts. | shotgun sequences of dna extracts from whole organisms allow a comprehensive assessment of possible symbionts. the current project makes use of four shotgun datasets from three species of the planktonic freshwater crustaceans daphnia: one dataset from clones of d. pulex and d. pulicaria and two datasets from one clone of d. magna. we analyzed these datasets with three aims: first, we search for bacterial symbionts, which are present in all three species. second, we search for evidence for cyanob ... | 2009 | 19383155 |
| mechanism of substrate and inhibitor binding of rhodobacter capsulatus xanthine dehydrogenase. | rhodobacter capsulatus xanthine dehydrogenase (xdh) is an (alphabeta)(2) heterotetrameric cytoplasmic enzyme that resembles eukaryotic xanthine oxidoreductases in respect to both amino acid sequence and structural fold. to obtain a detailed understanding of the mechanism of substrate and inhibitor binding at the active site, we solved crystal structures of r. capsulatus xdh in the presence of its substrates hypoxanthine, xanthine, and the inhibitor pterin-6-aldehyde using either the inactive des ... | 2009 | 19109249 |
| unusual temperature dependence of photosynthetic electron transfer due to protein dynamics. | the initial electron transfer rate and protein dynamics in wild type and five mutant reaction centers from rhodobacter sphaeroides have been studied as a function of temperature (10-295 k). detailed kinetic measurements of initial electron transfer in rhodobacter sphaeroides reaction centers can be quantitatively described by a reaction diffusion formalism at all temperatures from 10 to 295 k. in this model, the time course of electron transfer is determined by the ability of the protein to inte ... | 2009 | 19115814 |
| in vivo sensitivity of blue-light-dependent signaling mediated by appa/ppsr or prrb/prra in rhodobacter sphaeroides. | formation of photosynthesis complexes in rhodobacter sphaeroides is regulated in a redox- and light-dependent manner by the appa/ppsr and prrb/prra systems. while on the one hand, blue light is sensed by the flavin adenine dinucleotide-binding bluf domain of appa, on the other, light is absorbed by bacteriochlorophyll signals through prrb/prra. we show that much smaller quantities initiate the appa-mediated response to blue light than the bacteriochlorophyll-mediated response. | 2009 | 19395480 |
| active site of cytochrome cbb3. | cytochrome cbb(3) is the most distant member of the heme-copper oxidase family still retaining the following major feature typical of these enzymes: reduction of molecular oxygen to water coupled to proton translocation across the membrane. the thermodynamic properties of the six redox centers, five hemes and a copper ion, in cytochrome cbb(3) from rhodobacter sphaeroides were studied using optical and epr spectroscopy. the low spin heme b in the catalytic subunit was shown to have the highest m ... | 2009 | 19252222 |
| across membrane communication between the q(o) and q(i) active sites of cytochrome bc(1). | the ubihydroquinone:cytochrome c oxidoreductase (cyt bc(1)) contains two catalytically active domains, termed the hydroquinone oxidation (q(o)) and quinone reduction (q(i)) sites, which are distant from each other by over 30 a. previously, we have reported that binding of inhibitors to the q(i) site on one (n) side of the energy-transducing membrane changes the local environment of the iron-sulfur (fe/s) protein subunit residing in the q(o) site on the other (p) side of the lipid bilayer [cooley ... | 2009 | 19254042 |
| atomic force microscopy studies of native photosynthetic membranes. | in addition to providing the earliest surface images of a native photosynthetic membrane at submolecular resolution, examination of the intracytoplasmic membrane (icm) of purple bacteria by atomic force microscopy (afm) has revealed a wide diversity of species-dependent arrangements of closely packed light-harvesting (lh) antennae, capable of fulfilling the basic requirements for efficient collection, transmission, and trapping of radiant energy. a highly organized architecture was observed with ... | 2009 | 19265434 |
| microscopic pka analysis of glu286 in cytochrome c oxidase (rhodobacter sphaeroides): toward a calibrated molecular model. | as stringent tests for the molecular model and computational protocol, microscopic pk(a) calculations are performed for the key residue, glu286, in cytochrome c oxidase (cco) using a combined quantum mechanical/molecular mechanical (qm/mm) potential and a thermodynamic integration protocol. the impact of the number of water molecules in the hydrophobic cavity and protonation state of several key residues (e.g., his334, cu(b)-bound water, and prd(a3)) on the computed microscopic pk(a) values of g ... | 2009 | 19243111 |
| catalytic properties of the expressed acyclic carotenoid 2-ketolases from rhodobacter capsulatus and rubrivivax gelatinosus. | purple photosynthetic bacteria synthesize the acyclic carotenoids spheroidene and spirilloxanthin which are ketolated to spheroidenone and 2,2'-diketospirilloxanthin under aerobic growth. for the studies of the catalytic reaction of the ketolating enzyme, the crta genes from rubrivivax gelatinosus and rhodobacter capsulatus encoding acyclic carotenoid 2-ketolases were expressed in escherichia coli to functional enzymes. with the purified enzyme from the latter, the requirement of molecular oxyge ... | 2009 | 19136077 |
| light-activated cytotoxic compounds from malaysian microorganisms for photodynamic therapy of cancer. | photodynamic therapy (pdt) is a promising cancer treatment which involves activation of a photosensitizing drug with light to produce reactive oxygen species that kill tumors without causing damage to unirradiated normal tissues. to date, only photofrin, foscan and levulan have been approved for clinical treatment of cancer. tropical habitats such as those found in malaysia are attractive sources of new therapeutic compounds as tremendous chemical diversity is found in a large number of plants, ... | 2009 | 19125347 |
| epr evidence of cyanide binding to the mn(mg) center of cytochrome c oxidase: support for cu(a)-mg involvement in proton pumping. | we examined the anion binding behavior of the mg(mn) site in cytochrome c oxidase to test a possible role of this center in proton pumping. rhodobacter sphaeroides grown in a mn(ii)-rich medium replaces the intrinsic mg(ii) ion with an epr-detectable mn(ii) ion without change in activity. due to its close proximity and a shared ligand, oxidized cu(a) is spin-coupled to the mn(ii) ion, affecting the epr spectrum. an examination of both bovine and r.s. oxidase crystal structures reveals a hydrogen ... | 2009 | 19108635 |
| heterologous synthesis and assembly of functional lhii antenna complexes from rhodovulum sulfidophilum in rhodobacter sphaeroides mutant. | the light harvesting complexes, including lhii and lhi, are the important components of photosynthetic apparatus. rhodovulum (rdv.) sulfidophilum and rhodobacter (r.) sphaeroides belong to two genera of photosynthetic bacteria, and they are very different in some physiological characteristics and light harvesting complexes structure. the lhii structural genes (pucbsas) from rdv. sulfidophilum and the lhi structural genes (pufba) from r. sphaeroides were amplified, and cloned into an expression v ... | 2009 | 18850303 |
| kinetics of in vivo bacteriochlorophyll fluorescence yield and the state of photosynthetic apparatus of purple bacteria. | the light-induced electron transport in purple bacterium rhodobacter sphaeroides was studied in vivo by means of kinetic difference absorption spectroscopy and kinetics of bacteriochlorophyll fluorescence yield. measurements of redox state of the oxidised primary donor and cytochrome c and the membrane potential revealed a complex pattern of changes of the electron flow. effects of the membrane potential on the fluorescence yield were also analysed, and a model for the fluorescence induction cur ... | 2009 | 19199074 |
| characterization of d-tagatose-3-epimerase from rhodobacter sphaeroides that converts d-fructose into d-psicose. | a non-characterized gene, previously proposed as the d-tagatose-3-epimerase gene from rhodobacter sphaeroides, was cloned and expressed in escherichia coli. its molecular mass was estimated to be 64 kda with two identical subunits. the enzyme specificity was highest with d-fructose and decreased for other substrates in the order: d-tagatose, d-psicose, d-ribulose, d-xylulose and d-sorbose. its activity was maximal at ph 9 and 40 degrees c while being enhanced by mn(2+). at ph 9 and 40 degrees c, ... | 2009 | 19205890 |
| rna degradation in archaea and gram-negative bacteria different from escherichia coli. | exoribonucleolytic and endoribonucleolytic activities are important for controlled degradation of rna and contribute to the regulation of gene expression at the posttranscriptional level by influencing the half-lives of specific messenger rnas. the rna half-lives are determined by the characteristics of the rna substrates and by the availability and the properties of the involved proteins-ribonucleases and assisting polypeptides. much is known about rna degradation in eukarya and bacteria, but t ... | 2009 | 19215775 |
| functional analysis of a large non-conserved region of flgk (hap1) from rhodobacter sphaeroides. | the single subpolar flagellum of rhodobacter sphaeroides shows an enlarged hook-filament junction. one of the two proteins that compose this section of the filament is hap1(rs) (flgk(rs)) it contains a central non-conserved region of 860 amino acids that makes this protein about three times larger than its homologue in salmonella enterica serovar typhimurium. we investigated the role of this central portion of the unusually large hap1 protein of r. sphaeroides by monitoring the effects of serial ... | 2009 | 19003427 |
| lateral proton transfer between the membrane and a membrane protein. | proton transport across biological membranes is a key step of the energy conservation machinery in living organisms, and it has been proposed that the membrane itself plays an important role in this process. in the present study we have investigated the effect of incorporation of a proton transporter, cytochrome c oxidase, into a membrane on the protonation kinetics of a fluorescent ph-sensitive probe attached at the surface of the protein. the results show that proton transfer to the probe was ... | 2009 | 19166299 |
| different biochemical mechanisms ensure network-wide balancing of reducing equivalents in microbial metabolism. | to sustain growth, the catabolic formation of the redox equivalent nadph must be balanced with the anabolic demand. the mechanisms that ensure such network-wide balancing, however, are presently not understood. based on 13c-detected intracellular fluxes, metabolite concentrations, and cofactor specificities for all relevant central metabolic enzymes, we have quantified catabolic nadph production in agrobacterium tumefaciens, bacillus subtilis, escherichia coli, paracoccus versutus, pseudomonas f ... | 2009 | 19181802 |
| coenzyme binding and hydride transfer in rhodobacter capsulatus ferredoxin/flavodoxin nadp(h) oxidoreductase. | ferredoxin-nadp(h) reductases catalyse the reversible hydride/electron exchange between nadp(h) and ferredoxin/flavodoxin, comprising a structurally defined family of flavoenzymes with two distinct subclasses. those present in gram-negative bacteria (fprs) display turnover numbers of 1-5 s(-1) while the homologues of cyanobacteria and plants (fnrs) developed a 100-fold activity increase. we investigated nucleotide interactions and hydride transfer in rhodobacter capsulatus fpr comparing them to ... | 2009 | 18973834 |
| spectroscopic and computational studies of nitrite reductase: proton induced electron transfer and backbonding contributions to reactivity. | a combination of spectroscopy and dft calculations has been used to define the geometric and electronic structure of the nitrite bound type 2 (t2) copper site at high and low ph in nitrite reductase from rhodobacter sphaeroides. at high ph there is no electron transfer from reduced type 1 (t1) to the nitrite bound t2 copper, while protonation triggers t1 --> t2 electron transfer and generation of no. the dft calculated reaction coordinate for the n-o bond cleavage in nitrite reduction by the red ... | 2009 | 19053185 |
| lipopolysaccharide from rhodobacter capsulatus suppresses the effect of endotoxins from various e. coli chemotypes on the priming and apoptosis of human neutrophils. | 2009 | 19341104 | |
| the hupr receiver domain crystal structure in its nonphospho and inhibitory phospho states. | hydrogen uptake protein regulator (hupr) is a member of the nitrogen regulatory protein c (ntrc) family of response regulators. these proteins activate transcription by rna polymerase (rnap) in response to a change in environment. this change is detected through the phosphorylation of their receiver domain as part of a two-component signalling pathway. hupr is an unusual member of this family as it activates transcription when unphosphorylated, and transcription is inhibited by phosphorylation. ... | 2009 | 18977359 |
| serine in bluf domains displays spectral importance in computational models. | the bluf (blue-light sensing using flavine) domain of the appa photoreceptor protein from rhodobacter sphaeroides was modelled by using quantum chemical chromophore plus amino acid models at the (td-)b3lyp/6-31g * level of theory. the models were based on nmr structures, and further refined by charmm force field molecular dynamics simulations. the goal is to explain the total redshift by about 10nm in the uv/vis spectra of bluf domains after illumination, and to relate it to structural changes. ... | 2009 | 19036599 |
| mediated electrochemistry of dimethyl sulfoxide reductase from rhodobacter capsulatus. | electrochemically driven catalysis of the bacterial enzyme dimethyl sulfoxide (dmso) reductase (rhodobacter capsulatus) has been studied using the macrocyclic complex (trans-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine)cobalt(iii) as a mediator. in the presence of both dmso and dmso reductase, the normal transient co(iii/ii) voltammetric response of the complex is transformed into an amplified and sigmoidal (steady-state) waveform characteristic of a catalytic ec' mechanism. at l ... | 2009 | 19082848 |
| redox-dependent conformational changes in cytochrome c oxidase suggest a gating mechanism for proton uptake. | a role for conformational change in the coupling mechanism of cytochrome c oxidase is the subject of controversy. relatively small conformational changes have been reported in comparisons of reduced and oxidized crystal structures of bovine oxidase but none in bacterial oxidases. comparing the x-ray crystal structures of the reduced (at 2.15 a resolution) and oxidized forms of cytochrome c oxidase from rhodobacter sphaeroides, we observe a displacement of heme a(3) involving both the porphyrin r ... | 2009 | 19397279 |
| low-temperature studies of electron transfer to the m side of yfh reaction centers from rhodobacter capsulatus. | there have been extensive experimental and theoretical studies of the temperature dependence of the rates of electron transfer between the cofactors associated primarily with the l polypeptide (or a branch) in the bacterial photosynthetic reaction center (rc). the focus of this paper is to gain further insight into the temperature dependence of rate of initial electron transfer to the parallel cofactor chain associated mainly with the m polypeptide (or b branch), which is inactive in the native ... | 2009 | 19132840 |
| site directed mutagenesis of amino acid residues at the active site of mouse aldehyde oxidase aox1. | mouse aldehyde oxidase (maox1) forms a homodimer and belongs to the xanthine oxidase family of molybdoenzymes which are characterized by an essential equatorial sulfur ligand coordinated to the molybdenum atom. in general, mammalian aos are characterized by broad substrate specificity and an yet obscure physiological function. to define the physiological substrates and the enzymatic characteristics of maox1, we established a system for the heterologous expression of the enzyme in escherichia col ... | 2009 | 19401776 |
| expression of four pha genes involved in poly-beta-hydroxybutyrate production and accumulation in rhodobacter sphaeroides fj1. | a cluster of genes encoding polyhydroxybutyrate (phb) depolymerase (phaz), phb synthase (phac), phasin (phap), and the regulator protein (phar) was previously identified in rhodobacter sphaeroides fj1 (r. sphaeroides fj1). in this study, we investigated the role of the phar protein on the expression of the pha genes. immunoblot analysis revealed that the expressions of phap, phaz and phar genes in wild-type cells of r. sphaeroides fj1 are repressed during the active growth phase, with the except ... | 2009 | 19404680 |
| rhodobacter aestuarii sp. nov., a phototrophic alphaproteobacterium isolated from an estuarine environment. | an ovoid to rod-shaped, phototrophic, purple non-sulfur bacterium was isolated from a brown-coloured microbial mat from the brackish water of bhitarkanika mangrove forest, dangmal, orissa, india. cells of strain ja296(t) were gram-negative and motile, forming chains of four to eight cells. the colour of the cell suspension grown under anaerobic conditions in the light was yellowish green. bacteriochlorophyll a and the carotenoids spheroidene and spheroidenone of the spirilloxanthin series were p ... | 2009 | 19406806 |
| development of a dynamic delivery method for in vitro bioassays. | measuring the biological activity of hydrophobic chemicals using in vitro assays is challenging because their aqueous solubility is low and the high density of bio-suspensions strongly decreases the bioavailability of hydrophobic pollutants. dynamic dosing by partitioning from a stable polymer has a potential to overcome these limitations. poly(dimethylsiloxane) (pdms) was chosen due to its documented bio-compatibility and excellent partitioning properties. pdms sheets were loaded with five poly ... | 2009 | 19324392 |
| [enzymes of the citramalate cycle in rhodospirillum rubrum]. | rhodospirillum rubrum is among the bacteria that can assimilate acetate in the absence of isocitrate lyase, the key enzyme of glyoxylate shunt. previously we have suggested the functioning of a new anaplerotic cycle of acetate assimilation in this bacterium: citramalate cycle, where acetyl-coa is oxidized to glyoxylate. this work has demonstrated the presence of all the key enzymes of this cycle in r. rubrum extracts: citramalate synthase catalyzing condensation of acetyl-coa and pyruvate with t ... | 2009 | 19334594 |
| effect of subunit iv on superoxide generation by rhodobacter sphaeroides cytochrome bc(1) complex. | previous studies indicate that the three-subunit cytochrome bc(1) core complex of rhodobacter sphaeroides contains a fraction of the electron transfer activity of the wild-type enzyme. addition of subunit iv to the core complex increases electron transfer activity to the same level as that of the wild-type complex. this activity increase may result from subunit iv preventing electron leakage, from the low potential electron transfer chain, and reaction with molecular oxygen, producing superoxide ... | 2009 | 19348783 |
| protein-protein interactions between cbbr and rega (prra), transcriptional regulators of the cbb operons of rhodobacter sphaeroides. | cbbr and rega (prra) are transcriptional regulators of the cbb(i) and cbb(ii) (calvin-benson-bassham co(2) fixation pathway) operons of rhodobacter sphaeroides. both proteins interact specifically with promoter sequences of the cbb operons. rega has four dna binding sites within the cbb(i) promoter region, with the cbbr binding site and rega binding site 1 overlapping each other. this study demonstrated that cbbr and rega interact and form a discrete complex in vitro, as illustrated by gel mobil ... | 2009 | 19077171 |
| laterally mobile, functionalized self-assembled monolayers at the fluorous-aqueous interface in a plug-based microfluidic system: characterization and testing with membrane protein crystallization. | this paper describes a method to generate functionalizable, mobile self-assembled monolayers (sams) in plug-based microfluidics. control of interfaces is advancing studies of biological interfaces, heterogeneous reactions, and nanotechnology. sams have been useful for such studies, but they are not laterally mobile. lipid-based methods, though mobile, are not easily amenable to setting up the hundreds of experiments necessary for crystallization screening. here we demonstrate a method, complemen ... | 2009 | 19354215 |
| monitoring and interpretation of photoinduced biochemical processes by rapid-scan ftir difference spectroscopy and hybrid hard and soft modeling. | natural photochemical processes often require special instrumentation to monitor them at a suitable time scale. rapid-scan ftir difference spectroscopy is one of the preferred techniques to obtain rich structural information in the scale of milliseconds about photochemical processes of complex natural systems. the difference spectra obtained by this technique enhance the fine spectroscopic changes undergone during the process but require powerful data analysis methodologies to take full advantag ... | 2009 | 19385692 |
| relaxation mechanism of molecular systems containing hydrogen bonds and free energy temperature dependence of reaction of charges recombination within rhodobacter sphaeroides rc. | the mechanism of protonic relaxation is shown to take place in molecular systems containing hydrogen bonds. the mechanism arises from the proton redistribution between two stable states on hydrogen bond lines. this redistribution occurs due to changes of hydrogen bond double well potential, brought about by changes of the electronic state of a molecular system. a characteristic of the relaxation process is that it takes place due to the proton tunneling along hydrogen bonds. the charge shift cau ... | 2009 | 19247510 |
| a mitochondrial dna mutation linked to colon cancer results in proton leaks in cytochrome c oxidase. | an increasing number of cancer types have been found to be linked to specific mutations in the mitochondrial dna, which result in specific structural changes of the respiratory enzyme complexes. in this study, we have investigated the effect of 2 such mutations identified in colon cancer patients, leading to the amino acid substitutions ser458pro and gly125asp in subunit i of cytochrome c oxidase (complex iv) [greaves et al. (2006) proc natl acad sci usa 103:714-719]. we introduced these mutatio ... | 2009 | 19218458 |
| the local electric field within phospholipid membranes modulates the charge transfer reactions in reaction centres. | three different cholesterol derivatives and phloretin, known to affect the local electric field in phospholipid membranes, have been introduced into rhodobacter sphaeroides reaction centre-containing phospholipid liposomes. we show that cholesterol and 6-ketocholestanol significantly slow down the interquinone first electron transfer (approximately 10 times), whereas phloretin and 5-cholesten-3beta-ol-7-one leave the kinetics essentially unchanged. interestingly, the two former compounds have be ... | 2009 | 19306840 |
| mutant reaction centers of rhodobacter sphaeroides i(l177)h with strongly bound bacteriochlorophyll a: structural properties and pigment-protein interactions. | methods of photoinduced fourier transform infrared (ftir) difference spectroscopy and circular dichroism were employed for studying features of pigment-protein interactions caused by replacement of isoleucine l177 by histidine in the reaction center (rc) of the site-directed mutant i(l177)h of rhodobacter sphaeroides. a functional state of pigments in the photochemically active cofactor branch was evaluated with the method of photo-accumulation of reduced bacteriopheophytin h(a)(-). the results ... | 2009 | 19232051 |
| trapping the p+b(l)- initial intermediate state of charge separation in photosynthetic reaction centers from rhodobacter capsulatus. | the short-lived (<1 ps) initial intermediate state p(+)b(l)(-) in the photoinduced charge separation process of the bacterial photosynthetic reaction center has been trapped in two d(ll)-based rhodobacter capsulatus mutants that have tyr at position m208 and lack the bacteriopheophytin electron acceptor h(l). transient state p(+)b(l)(-) is characterized by a 1017 nm bacteriochlorophyll anion absorption band and decays by charge recombination with a lifetime of several hundred picoseconds at 295 ... | 2009 | 19245209 |
| regulation of gene expression by prra in rhodobacter sphaeroides 2.4.1: role of polyamines and dna topology. | in the present study, we show in vitro binding of prra, a global regulator in rhodobacter sphaeroides 2.4.1, to the prra site 2, within the rsp3361 locus. specific binding, as shown by competition experiments, requires the phosphorylation of prra. the binding affinity of prra for site 2 was found to increase 4- to 10-fold when spermidine was added to the binding reaction. the presence of extracellular concentrations of spermidine in growing cultures of r. sphaeroides gave rise to a twofold incre ... | 2009 | 19411327 |
| internal charge transfer in cytochrome c oxidase at a limited proton supply: proton pumping ceases at high ph. | in the membrane-bound enzyme cytochrome c oxidase, electron transfer from cytochrome c to o(2) is linked to proton uptake from solution to form h(2)o, resulting in a charge separation across the membrane. in addition, the reaction drives pumping of protons across the membrane. | 2009 | 19344748 |
| bacterial ortholog of mammalian translocator protein (tspo) with virulence regulating activity. | the translocator protein (tspo), previously designated as peripheral-type benzodiazepine receptor, is a protein mainly located in the outer mitochondrial membrane of eukaryotic cells. tspo is implicated in major physiological functions and functionally associated with other proteins such as the voltage-dependent anionic channel, also designated as mitochondrial porin. surprisingly, a tspo-related protein was identified in the photosynthetic bacterium rhodobacter sphaeroides but it was initially ... | 2009 | 19564920 |
| functional hydration and conformational gating of proton uptake in cytochrome c oxidase. | cytochrome c oxidase couples the reduction of dioxygen to proton pumping against an electrochemical gradient. the d-channel, a 25-a-long cavity, provides the principal pathway for the uptake of chemical and pumped protons. a water chain is thought to mediate the relay of protons via a grotthuss mechanism through the d-channel, but it is interrupted at n139 in all available crystallographic structures. we use free-energy simulations to examine the proton uptake pathway in the wild type and in sin ... | 2009 | 19248790 |
| substrate orientation and catalysis at the molybdenum site in xanthine oxidase: crystal structures in complex with xanthine and lumazine. | xanthine oxidoreductase is a ubiquitous cytoplasmic protein that catalyzes the final two steps in purine catabolism. we have previously investigated the catalytic mechanism of the enzyme by rapid reaction kinetics and x-ray crystallography using the poor substrate 2-hydroxy-6-methylpurine, focusing our attention on the orientation of substrate in the active site and the role of arg-880 in catalysis. here we report additional crystal structures of as-isolated, functional xanthine oxidase in the c ... | 2009 | 19109252 |
| modelling mitochondrial dna mutations in bacterial cytochrome c oxidase: link to colon cancer? | 2009 | 19447926 | |
| plasmon-waveguide resonance studies of ligand binding to integral proteins in membrane fragments derived from bacterial and mammalian cells. | a procedure has been developed for directly depositing membrane fragments derived from bacterial cells (chromatophores from rhodopseudomonas sphaeroides) and mammalian cells (mu-opioid receptor- and mc4 receptor-transfected human embryonic kidney (hek) cells and rat trigeminal ganglion cells) on the silica surface of a plasmon-waveguide resonance (pwr) spectrometer. binding of ligands (cytochrome c(2) for the chromatophores, the peptide agonists damgo and melanotan-ii that are specific for the m ... | 2009 | 19454250 |
| coenzyme q10 production by rhodobacter sphaeroides in stirred tank and in airlift bioreactor. | a higher coenzyme q(10) (coq(10)) concentration of 25.04 mg/l was found in airlift bioreactor than the value of 18.11 mg/l obtained in stirred tank under the aerobic-dark cultivation of rhodobacter sphaeroides. aeration rate didn't show obvious impact to coq(10) production in airlift bioreactor. the fed-batch operation in airlift bioreactor could increase the biomass concentration and led to the maximum coq(10) concentration of 33.91 mg/l measured, but a lower coq(10) cell content (3.5 mg coq(10 ... | 2009 | 19153771 |
| profile hidden markov models for analyzing similarities and dissimilarities in the bacterial reaction center and photosystem ii. | the bacterial photosynthetic reaction center is the evolutionary ancestor of the photosystem ii reaction center. these proteins share the same fold and perform the same biological function. nevertheless, the details of their molecular reaction mechanism differ. it is of significant biological and biochemical interest to determine which functional characteristics are conserved at the level of the protein sequences. since the level of sequence identity between the bacterial photosynthetic reaction ... | 2009 | 19159220 |
| proton-transfer pathways in photosynthetic reaction centers analyzed by profile hidden markov models and network calculations. | in the bacterial reaction center (brc) of rhodobacter sphaeroides, the key residues of proton transfer to the secondary quinone (q(b)) are known. also, several possible proton entry points and proton-transfer pathways have been proposed. however, the mechanism of the proton transfer to q(b) remains unclear. the proton transfer to q(b) in the brc of blastochloris viridis is less explored. to analyze whether the brcs of different species use the same key residues for proton transfer to q(b), we de ... | 2009 | 19285988 |
| genetic determinants of silicibacter sp. tm1040 motility. | silicibacter sp. tm1040 is a member of the marine roseobacter clade of alphaproteobacteria that forms symbioses with unicellular eukaryotic phytoplankton, such as dinoflagellates. the symbiosis is complex and involves a series of steps that physiologically change highly motile bacteria into cells that readily form biofilms on the surface of the host. the initial phases of symbiosis require bacterial motility and chemotaxis that drive the swimming bacteria toward their planktonic host. cells lack ... | 2009 | 19482930 |
| kinetic model of hydrogen generation by rhodobacter sphaeroides in the presence of nh ions. | to examine the effects of ammonium ion concentration and illumination intensity on the effectivness of the hydrogen generation process of rhodobacter sphaeroides. | 2009 | 19486388 |
| identification of ftir bands due to internal water molecules around the quinone binding sites in the reaction center from rhodobacter sphaeroides. | the bacterial reaction center (rc) is a membrane protein complex that performs photosynthetic electron transfer from a bacteriochlorophyll dimer to quinone acceptors q(a) and q(b). q(b) accepts electrons from the primary quinone, q(a), in two sequential electron transfer reactions coupled to uptake of a proton from solution. it has been suggested that water molecules along the proton uptake pathway are protonated upon quinone reduction on the basis of ftir difference spectra [breton, j., and nab ... | 2009 | 19161296 |
| the petite purple photosynthetic powerpack. | photoreaction centres are nature's solar batteries. these nanometre-scale power producers are responsible for transducing the energy of sunlight into a form that can be used by biological systems, thereby powering most of the biological activity on the planet. although to the layman the word 'photosynthesis' is usually associated with green plants, much of our understanding of the molecular basis of biological transduction of light energy has come from studies of purple photosynthetic bacteria. ... | 2009 | 19290870 |
| characterization of an unusual lov domain protein in the alpha-proteobacterium rhodobacter sphaeroides. | the facultatively phototrophic purple bacterium rhodobacter sphaeroides 2.4.1 harbors a lov (light, oxygen and voltage) domain protein, which shows a particular structure. lov domains perceive blue light by a noncovalently bound flavin and transmit the signal to various coupled output domains. proteins, that harbor a lov core, function e.g. as phototropins or circadian clock regulators. jalpha helices, which act as linker between the lov core and the output domain, were shown to be involved in t ... | 2009 | 19508644 |
| modification of galactitol dehydrogenase from rhodobacter sphaeroides d for immobilization on polycrystalline gold surfaces. | galactitol dehydrogenase (gatdh) from rhodobacter sphaeroides is a multifunctional enzyme that catalyzes in the presence of oxidized beta-nicotinamide adenine dinucleotide (nad(+)) the interconversion of various multivalent aliphatic alcohols to the corresponding ketones. the recombinant gatdh was provided with an n-terminal his(6)-tag to which distally up to three cysteine residues were attached. this protein construct maintained nearly full enzymatic activity, and it could be covalently immobi ... | 2009 | 19778027 |
| femtosecond phase of charge separation in reaction centers of chloroflexus aurantiacus. | difference absorption spectroscopy with temporal resolution of approximately 20 fsec was used to study the primary phase of charge separation in isolated reaction centers (rcs) of chloroflexus aurantiacus at 90 k. an ensemble of difference (light-minus-dark) absorption spectra in the 730-795 nm region measured at -0.1 to 4 psec delays relative to the excitation pulse was analyzed. comparison with analogous data for rcs of hm182l mutant of rhodobacter sphaeroides having the same pigment compositi ... | 2009 | 19817684 |
| photooxidative stress-induced and abundant small rnas in rhodobacter sphaeroides. | exposure to oxygen and light generates photooxidative stress by the bacteriochlorophyll a mediated formation of singlet oxygen ((1)o(2)) in rhodobacter sphaeroides. our study reports the genome-wide search for small rnas (srnas) involved in the regulatory response to (1)o(2). by using 454 pyrosequencing and northern blot analysis, we identified 20 srnas from r. sphaeroides aerobic cultures or following treatment with (1)o(2) or superoxide (o(-)(2)). one srna was specifically induced by (1)o(2) a ... | 2009 | 19906181 |
| primary processes of charge separation in reaction centers of ym210l/fm197y and ym210l mutants of rhodobacter sphaeroides. | difference femtosecond absorption spectroscopy with 20-fsec temporal resolution was applied to study a primary stage of charge separation and transfer processes in reaction centers of ym210l and ym210l/fm197y site-directed mutants of the purple bacterium rhodobacter sphaeroides at 90 k. photoexcitation was tuned to the absorption band of the primary electron donor p at 880 nm. coherent oscillations in the kinetics of stimulated emission of p* excited state at 940 nm and of anion absorption of mo ... | 2009 | 19916934 |
| bio-hydrogen production using a two-stage fermentation process. | a two-stage fermentation process consisting of dark and photo-fermentation periods was carried out in a batch reactor. in the first stage, glucose was fermented in the dark stage using clostridium saccharoperbutylacetonicum n1-4 (atcc 13564; csn1-4) to produce acetate, co2 and h2. the acetate produced in the first stage is fermented to h2 and co2 by rhodobacter sphaeroides ncimb 8253 for further hydrogen production in the second, illuminated stage. the yield of hydrogen in the first stage was ab ... | 2009 | 20180320 |
| excitation and electron transfer in reaction centers from rhodobacter sphaeroides probed and analyzed globally in the 1-nanosecond temporal window from 330 to 700 nm. | global analysis of a set of room temperature transient absorption spectra of rhodobacter sphaeroides reaction centers, recorded in wide temporal and spectral ranges and triggered by femtosecond excitation of accessory bacteriochlorophylls at 800 nm, is presented. the data give a comprehensive review of all spectral dynamics features in the visible and near uv, from 330 to 700 nm, related to the primary events in the rb. sphaeroides reaction center: excitation energy transfer from the accessory b ... | 2009 | 19890535 |
| light harvesting complex ii b850 excitation dynamics. | the dynamics of excitation energy transfer within the b850 ring of light harvesting complex 2 from rhodobacter sphaeroides and between neighboring b850 rings is investigated by means of dissipative quantum mechanics. the assumption of boltzmann populated donor states for the calculation of intercomplex excitation transfer rates by generalized forster theory is shown to give accurate results since intracomplex exciton relaxation to near-boltzmann population exciton states occurs within a few pico ... | 2009 | 20001083 |
| the electronic structure of the primary electron donor of reaction centers of purple bacteria at atomic resolution as observed by photo-cidnp 13c nmr. | composed of the two bacteriochlorophyll cofactors, p(l) and p(m), the special pair functions as the primary electron donor in bacterial reaction centers of purple bacteria of rhodobacter sphaeroides. under light absorption, an electron is transferred to a bacteriopheophytin and a radical pair is produced. the occurrence of the radical pair is linked to the production of enhanced nuclear polarization called photochemically induced dynamic nuclear polarization (photo-cidnp). this effect can be use ... | 2009 | 20018724 |
| [use of the standard theory of electronic transitions in the description of oscillations in the kinetics of electron transfer in reaction centers of purple bacteria]. | the standard theory of the electron transfer between donor and acceptor molecules was used to describe oscillations in the reduction kinetics of the intermediate electron acceptor ba and the primary electron acceptor ha. the kinetics of the reduction of ba and ha were simulated on the basis of the model in which one and two accepting modes were used. a principal experiment is offered for the selection of the suitable theory for adequate description of oscillations in the kinetics of electron tra ... | 2009 | 20067182 |
| structural model and excitonic properties of the dimeric rc-lh1-pufx complex from rhodobacter sphaeroides. | the light-harvesting apparatus of the purple bacterial photosynthetic unit consists of a pool of peripheral light-harvesting complexes that transfer excitation energy to a reaction center (rc) via the surrounding pigment-protein complex lh1. recent electron microscopy and atomic force microscopy studies have revealed that rc-lh1 units of rhodobacter sphaeroides form membrane-bending dimeric complexes together with the polypeptide pufx. we present a structural model for these rc-lh1-pufx dimeric ... | 2009 | 20161332 |
| the effect of aeration, agitation and light on biohydrogen production by rhodobacter sphaeroides ncimb 8253. | photo fermentation is a biological process that can be applied for hydrogen production. the process is environmental friendly which is operated under mild conditions using renewable resources. in order to increase yield of h2 produced by rhodobacter sphaeroides, some experimental factors that may enhance h2 production were studied. the effect of operating parameters including agitation, aeration and light on hydrogen production using r. sphaeroides ncimb 8253 was investigated. rhodobacter sphaer ... | 2009 | 20384278 |
| electron transfer from cytochrome c(2) to the reaction center: a transition state model for ionic strength effects due to neutral mutations. | interprotein electron transfer plays an important role in biological energy conversion. in this work, the electron transfer reaction between cytochrome c(2) (cyt) and the reaction center (rc) was studied to determine the mechanisms coupling association and electron transfer. previous studies have shown that mutation of hydrophobic residues in the reaction interface, particularly tyr l162, changes the binding affinity and rates of electron transfer at low ionic strengths. in this study, the effec ... | 2009 | 19877711 |
| a model invalidation-based approach for elucidating biological signalling pathways, applied to the chemotaxis pathway in r. sphaeroides. | developing methods for understanding the connectivity of signalling pathways is a major challenge in biological research. for this purpose, mathematical models are routinely developed based on experimental observations, which also allow the prediction of the system behaviour under different experimental conditions. often, however, the same experimental data can be represented by several competing network models. | 2009 | 19878602 |
| biological synthesis of size-controlled cadmium sulfide nanoparticles using immobilized rhodobacter sphaeroides. | size-controlled cadmium sulfide nanoparticles were successfully synthesized by immobilized rhodobacter sphaeroides in the study. the dynamic process that cd(2+) was transported from solution into cell by living r. sphaeroides was characterized by transmission electron microscopy (tem). culture time, as an important physiological parameter for r. sphaeroides growth, could significantly control the size of cadmium sulfide nanoparticles. tem demonstrated that the average sizes of spherical cadmium ... | 2009 | 20596372 |
| the flagellar protein flil is essential for swimming in rhodobacter sphaeroides. | in this work we characterize the function of the flagellar protein flil in rhodobacter sphaeroides. our results show that flil is essential for motility in this bacterium and that in its absence flagellar rotation is highly impaired. a green fluorescent protein (gfp)-flil fusion forms polar and lateral fluorescent foci that show different spatial dynamics. the presence of these foci is dependent on the expression of the flagellar genes controlled by the master regulator fleq, suggesting that add ... | 2010 | 20889747 |