PMID(sorted descending)
reactivation of the chloroplast cf1-atpase beta subunit by trace amounts of the cf1 alpha subunit suggests a chaperonin-like activity for cf1 alpha.incubation of tobacco and lettuce thylakoids with 2 m licl in the presence of mgatp removes the beta subunit from their cf1-atpase (cf1 beta) together with varying amounts of the cf1 alpha subunit (cf1 alpha). these 2 m licl extracts, as with the one obtained from spinach thylakoids (avital, s., and gromet-elhanan, z. (1991) j. biol. chem. 266, 7067-7072), could form active hybrid atpases when reconstituted into inactive beta-less rhodospirillum rubrum chromatophores. pure cf1 beta fractions tha ...19911673460
an electrochemical assay for the characterization of redox proteins from biological electron transfer chains.a sensitive and quick assay for redox proteins based on electrochemical titrations in a thin-layer electrochemical cell is described. using a combination of modified-electrode and "mediator-enhanced" electrochemistry, equilibration of the cell volume (4 microliters) with the applied potential allows series of spectra as a function of the potential to be recorded rapidly. a complete redox titration between +500 and -600 mv (vs ag/agcl/3 m kcl) in 30-mv intervals takes approximately 2 h. the detec ...19911667456
immunological cross-reactivity between proton-pumping inorganic pyrophosphatases of widely phylogenic separated species.immunological cross-reactivity among three types of inorganic pyrophosphatases, that is, the proton pumping inorganic pyrophosphate synthase (h(+)-ppi synthase) and the soluble inorganic pyrophosphatase, both from rhodospirillum rubrum, and the vacuolar membrane inorganic pyrophosphatase (h(+)-ppase) from mung bean (vigna radiata), were examined by means of immunoblot analyses. antibodies raised against the mung bean h(+)-ppase cross-reacted with the h(+)-ppi synthase from r. rubrum but not with ...19911662506
an improved tn7-based system for the single-copy insertion of cloned genes into chromosomes of gram-negative bacteria.a system is described for the single-copy, stable insertion of cloned dna sequences into the chromosomes of gram- bacteria. two narrow-host-range plasmids form the basis of this system: the 'carrier' plasmid contains the mini tn7-km transposon, into which foreign dna can be cloned; the 'helper' plasmid provides the tn7 transposition functions in trans. both plasmids are readily transferred into gram- bacteria by conjugation. the functionality of this system has been demonstrated in rhodospirillu ...19911661697
structural and functional features of pseudomonas cytochrome c peroxidase.the secondary structure of pseudomonas cytochrome c peroxidase (ferrocytochrome c: hydrogen-peroxide oxidoreductase, ec has been predicted from the established amino acid sequence of the enzyme using a chou-fasman-type algorithm. the amount of alpha-helicity thus obtained is in agreement with previously obtained results based on circular dichroic measurements at far uv. the two heme c moieties of the enzyme have earlier been shown to have widely different characteristics, e.g., the red ...19911657179
electron transfer proteins of the purple phototrophic bacterium, rhodopseudomonas rutila.the soluble electron transfer protein content of rhodopseudomonas rutila was found to consist of two basic cytochromes and a (4fe-4s) ferredoxin. cytochrome c' was easily identified by its characteristic high spin absorption spectra. the native molecular weight is 29,000 and the subunit is 14,000. cytochrome c-550 has low spin absorption spectra and a high redox potential (376 mv) typical of cytochromes c2. the molecular weight is about 14,000. the ferredoxin is apparently a dimer (43,000) of ap ...19911654788
electrostatic effects on the kinetics of electron transfer reactions of cytochrome c caused by binding to negatively charged lipid bilayer vesicles.the effect of binding reduced tuna mitochondrial cytochrome c to negatively charged lipid bilayer vesicles at low ionic strength on the kinetics of electron transfer to various oxidants was studied by stopped-flow spectrophotometry. binding strongly stimulated (up to 100-fold) the rate of reaction with the positively charged cobalt phenanthroline ion, whereas the rate of reaction with the negatively charged ferricyanide ion was greatly inhibited (up to 60-fold), as compared with the same systems ...19911654779
cytochrome c' of paracoccus denitrificans.cytochrome c' was identified in periplasmic extracts of the paracoccus denitrificans strains lmd 22.21 and lmd 52.44. the cytochrome c' was purified from the latter using the device of sequential molecular exclusion chromatography in the dimeric and monomeric states. although showing the overall spectroscopic features of the cytochrome c' family, the paracoccus cytochrome c' is unusual in having a red-shifted oxidised soret band at 407 nm. also unusual is the midpoint potential of 202 mv, well a ...19911653018
molecular structure of cytochrome c2 isolated from rhodobacter capsulatus determined at 2.5 a resolution.the molecular structure of the cytochrome c2, isolated from the purple photosynthetic bacterium rhodobacter capsulatus, has been solved to a nominal resolution of 2.5 a and refined to a crystallographic r-factor of 16.8% for all observed x-ray data. crystals used for this investigation belong to the space group r32 with two molecules in the asymmetric unit and unit cell dimensions of a = b = 100.03 a, c = 162.10 a as expressed in the hexagonal setting. an interpretable electron density map calcu ...19911651396
genetic analysis of photosynthesis in rhodospirillum centenum.a genetic system has been developed for studying bacterial photosynthesis in the recently described nonsulfur purple photosynthetic bacterium rhodospirillum centenum. nonphotosynthetic mutants of r. centenum were obtained by enrichment for spontaneous mutations, by ethyl methanesulfonate mutagenesis coupled to penicillin selection on solid medium, and by tn5 transposition mutagenesis with an incp plasmid vector containing a temperature-sensitive origin of replication. in vivo and in vitro charac ...19911648078
the rhodospirillum rubrum cytochrome bc1 complex: redox properties, inhibitor sensitivity and proton pumping.a detergent-solubilized, three-subunit-containing cytochrome bc1 complex, isolated from the photosynthetic bacterium r. rubrum, has been shown to be highly sensitive to stigmatellin, myxothiazol, antimycin a and uhdbt, four specific inhibitors of these complexes. oxidation-reduction titrations have allowed the determination of em values for all the electron-carrying prosthetic groups in the complex. antimycin a has been shown to produce a red shift in the alpha-band absorbance maximum of one of ...19911646633
ligand binding properties of cytochromes c'.the cytochromes c' bind co, alkylisocyanides and cn- with rate and equilibrium constants which are 10(2)- to 10(6)-fold smaller than other high-spin hemoproteins. the decreased affinity for exogenous ligands is largely associated with steric interactions at the heme coordination site. while co and alkylisocyanides bind noncooperatively to the dimeric rhodospirillum molischianum cytochrome c', co, alkylisocyanides and cn- appear to bind cooperatively to the dimeric chromatium vinosum cytochrome c ...19911646027
high-resolution 1h- and 15n-nmr studies of rhodospirillum rubrum cytochrome c2.rhodospirillum rubrum cytochrome c2 was uniformly enriched in 15n and studied by 1h- and 15n-nmr spectroscopy. relaxation and noe data allowed determination of the rotational correlation time and indicated more rapid side-chain motion in the native protein and increased segmental motion in the base-denatured protein. the pi nitrogen of the ligand histidine and the indolic nitrogen of the invariant tryptophan both remain protonated and act as proton-donors in hydrogen bonds over a wide ph range a ...19911646025
sequence variability in bacterial cytochromes c.cytochromes c are proteins that can be defined both phenotypically and by their possession of a characteristic sequence motif. many sequences from bacterial sources are known, and new ones are being reported every year. an analysis can be made as to what fraction of new sequences are members of already known classes or subclasses, and how many map into previously uninhabited regions of sequence space.19911646017
functional size analysis of pyrophosphatase from rhodospirillum rubrum determined by radiation inactivation.a radiation inactivation technique was employed to determine the functional size of pyrophosphatase (ppase) from the chromatophores of rhodospirillum rubrum. the activities of hydrolysis and synthesis reactions of pyrophosphatase and its coupled proton translocation decayed in a simple exponential function with the increase of radiation dosages. d37 values of 5.2 +/- 0.7 and 5.8 +/- 0.8 mrads were obtained for pyrophosphate hydrolysis and its associated proton translocation yielding molecular ma ...19911645297
genetic and physiological characterization of the rhodospirillum rubrum carbon monoxide dehydrogenase system.a 3.7-kb dna region encoding part of the rhodospirillum rubrum co oxidation (coo) system was identified by using oligonucleotide probes. sequence analysis of the cloned region indicated four complete or partial open reading frames (orfs) with acceptable codon usage. the complete orfs, the 573-bp coof and the 1,920-bp coos, encode an fe/s protein and the ni-containing carbon monoxide dehydrogenase (codh), respectively. the four 4-cysteine motifs encoded by coof are typical of a class of proteins ...19921644755
direct electrochemical studies of hydrogenase and co dehydrogenase.the reduction potentials of two relatively high-molecular-mass enzymes were determined directly at an edge pyrolytic graphite electrode by using square-wave voltammetry. the equilibrium reduction potential versus standard hydrogen electrode was determined for clostridium pasteurianum hydrogenase i (e'0 = -377 +/- 10 mv; molecular mass 60 kda) and rhodospirillum rubrum carbon monoxide dehydrogenase (e'0 = -418 +/- 7 mv; molecular mass 62 kda). the reduction potential of each enzyme was ph-indepen ...19921637298
enhancement of carotenoid-to-chlorophyll singlet energy transfer by carotenoid-carotenoid interaction.the apparent quantum yield of singlet-singlet spirilloxanthin-to-bacteriochlorophyll a energy transfer increases linearly with the residual spirilloxanthin content in rhodospirillum rubrum membrane vesicles from which this carotenoid has been partially removed. since it has been previously shown that carotenoid-carotenoid interaction is a linear function of the residual spirilloxanthin level in the major pigment-protein complex of those vesicles (zurdo, j., r. m. lozano, c. fernandez-cabrera, an ...19921617133
the relation between the soluble factor associated with h(+)-transhydrogenase of rhodospirillum rubrum and the enzyme from mitochondria and escherichia coli.although in mitochondria, escherichia coli and rhodobacter capsulatus the h(+)-transhydrogenases are intrinsic membrane proteins, in rhodospirillum rubrum a water-soluble component (ths) and a membrane-bound component are together required for activity. ths was selectively removed from chromatophore membranes of rhs. rubrum and was purified to homogeneity by precipitation with (nh4)2so4 and ion-exchange, affinity dye and gel exclusion chromatography. the latter indicated an mr of approx. 74,000 ...19921610876
substitution of asp193 to asn at the active site of ribulose-1,5-bisphosphate carboxylase results in conformational changes.the crystal structure of a mutant of ribulose bisphosphate carboxylase/oxygenase from rhodospirillium rubrum, where asp193, one of the ligands of the magnesium ion at the activator site, is replaced by asn, has been determined to a nominal resolution of 0.26 nm. the mutation of asp to asn induces both local and global conformation changes as follows. the side chain of asn193 moves away from the active site and interacts with main-chain oxygen of residue 165, located in the neighbouring strand be ...19921606957
electrostatic fields at the active site of ribulose-1,5-bisphosphate carboxylase.a macroscopic approach has been employed to calculate the electrostatic potential field of nonactivated ribulose-1,5-bisphosphate carboxylase and of some complexes of the enzyme with activator and substrate. the overall electrostatic field of the l2-type enzyme from the photosynthetic bacterium rhodospirillum rubrum shows that the core of the dimer, consisting of the two c-terminal domains, has a predominantly positive potential. these domains provide the binding sites for the negatively charged ...19921603801
mutation of asparagine 111 of rubisco from rhodospirillum rubrum alters the carboxylase/oxygenase specificity.the conserved asparagine 111 of ribulose-1,5-bisphosphate carboxylase/oxygenase from the photosynthetic bacteria rhodospirillum rubrum was identified as a candidate for a side-chain that might be involved in the carboxylase/oxygenase specificity. it was replaced by site-directed mutagenesis with aspartic acid, leucine, glutamine or glycine residues. the mutant enzymes exhibit a very low carboxylase activity compared with the wild-type enzyme. the values of km(rubp) and kcat for asn111----gly, th ...19921602488
on the structure of the nickel/iron/sulfur center of the carbon monoxide dehydrogenase from rhodospirillum rubrum: an x-ray absorption spectroscopy study.the nickel/iron/sulfur center of the carbon monoxide dehydrogenase (carbon monoxide:(acceptor)oxidoreductase; ec enzyme from rhodospirillum rubrum (rr-codh) was studied by x-ray absorption spectroscopy at the ni k edge. extended x-ray absorption fine structure data show that the first ni coordination shell consists of 2 s atoms at 2.23 a and 2-3 n/o atoms at 1.87 a. the edge structure indicates a distorted tetrahedral or five-coordinate ni environment in both oxidized and reduced rr-co ...19921584775
cloning, sequencing, mutagenesis, and functional characterization of drat and drag genes from azospirillum brasilense.the azospirillum brasilense drat gene, encoding dinitrogenase reductase atp-ribosyltransferase, and drag gene, encoding dinitrogenase reductase activating glycohydrolase, were cloned and sequenced. two genes were contiguous on the a. brasilense chromosome and showed extensive similarity to the same genes from rhodospirillum rubrum. analysis of mutations introduced into the dra region on the a. brasilense chromosome showed that mutants affected in drat were incapable of regulating nitrogenase act ...19921577701
role of asparagine-111 at the active site of ribulose-1,5-bisphosphate carboxylase/oxygenase from rhodospirillum rubrum as explored by site-directed mutagenesis.crystallographic studies of ribulose-1,5-bisphosphate carboxylase/oxygenase from rhodospirillum rubrum suggest that active-site asn111 interacts with mg2+ and/or substrate (lundqvist, t., and schneider, g. (1991) j. biol. chem. 266, 12604-12611). to examine possible catalytic roles of asn111, we have used site-directed mutagenesis to replace it with a glutaminyl, aspartyl, seryl, or lysyl residue. although the mutant proteins are devoid of detectable carboxylase activity, their ability to form a ...19921569095
characterization of lhi- and lhi+ rhodobacter capsulatus pufa mutants.the nh2 termini of light-harvesting complex i (lhi) polypeptides alpha and beta of rhodobacter capsulatus are thought to be involved in the assembly of the lhi complex. for a more detailed study of the role of the nh2-terminal segment of the lhi alpha protein in insertion into the intracytoplasmic membrane (icm) of r. capsulatus, amino acids 6 to 8, 9 to 11, 12 and 13, or 14 and 15 of the lhi alpha protein were deleted. additionally, the hydrophobic stretch of the amino acids 7 to 11 was lengthe ...19921569029
enhanced co2/o2 specificity of a site-directed mutant of ribulose-bisphosphate carboxylase/oxygenase.the co2/o2 specificity factor of ribulose-bisphosphate carboxylase/oxygenase partially determines the efficiency of photosynthetic carbon assimilation. heretofore, engineered alterations of the enzyme have only decreased the selectivity for co2 utilization. we show that alanyl replacement of active-site ser-368 of the rhodospirillum rubrum carboxylase enhances the carboxylation selectivity approximately 1.6-fold over the wild-type level. this enhancement reflects a greater relative decline in ox ...19921551863
purification and characterization of glutathione reductase from rhodospirillum rubrum.glutathione reductase (nad(p)h:gssg oxidoreductase ec was purified 1160-fold to homogeneity from the nonsulfurous purple bacteria rhodospirillum rubrum (wild type). specific activity of the pure preparation was 102 u/mg. the enzyme displayed a typical flavoprotein absorption spectrum with maxima at 274,365, and 459 nm and an absorbance ratio a280/a459 of 7.6. the amino acid analysis revealed an unusually high content of glycine and arginine residues. titration of the enzyme with 5,5'-d ...19921524433
studies on the effect of nad(h) on nitrogenase activity in rhodospirillum rubrum.the effect of nad(p) and analogs of this nucleotide on nitrogenase activity in rhodospirillum rubrum has been studied. addition of nad+ to nitrogen fixing rsp. rubrum leads to inhibition of nitrogenase. nadp+ has the same effect but nadh or analogs modified in the nicotinamide portion do not cause inhibition. in contrast to ammonium ions, addition of nad+ leads to inhibition of nitrogenase in cells that have been n-starved under argon. the inhibitory effect of nad+ is more pronounced at lower li ...19921510568
dynamics of energy transfer and trapping in the light-harvesting antenna of rhodopseudomonas low intensity picosecond absorption spectroscopy it is shown that the exciton lifetime in the light-harvesting antenna of rhodopseudomonas (rps.) viridis membranes with photochemically active reaction centers at room temperature is 60 +/- 10 ps. this lifetime reflects the overall trapping rate of the excitation energy by the reaction center. with photochemically inactive reaction centers, in the presence of p+, the exciton lifetime increases to 150 +/- 15 ps. prereducing the secondary electro ...19921504241
cloning of poly(3-hydroxybutyric acid) synthase genes of rhodobacter sphaeroides and rhodospirillum rubrum and heterologous expression in alcaligenes eutrophus.from genomic libraries of the purple non-sulfur bacteria rhodospirillum rubrum ha and rhodobacter sphaeroides atcc 17023 in the broad-host range cosmid pvk100, we cloned a 15- and a 14-kbp hindiii restriction fragment, respectively. each of these fragments restored the ability to accumulate poly(3-hydroxybutyrate) (phb), in the phb-negative mutant alcaligenes eutrophus phb-4. these hybrid cosmids also complemented phb-negative mutants derived from wild-type r. rubrum or r. sphaeroides. both frag ...19921499989
molecular basis for biosynthesis and accumulation of polyhydroxyalkanoic acids in bacteria.the current knowledge on the structure and on the organization of polyhydroxyalkanoic acid (pha)-biosynthetic genes from a wide range of different bacteria, which rely on different pathways for biosynthesis of this storage polyesters, is provided. molecular data will be shown for genes of alcaligenes eutrophus, purple non-sulfur bacteria, such as rhodospirillum rubrum, purple sulfur bacteria, such as chromatium vinosum, pseudomonads belonging to rrna homology group i, such as pseudomonas aerugin ...19921476773
restoration of the wild-type locus in an rubp carboxylase/oxygenase mutant of synechocystis pcc 6803 via targeted gene recombination.the interaction between homologous dna sequences, distant from each other in the chromosome, was examined in the cyanobacterium synechocystis pcc 6803. most of the rbcl gene encoding the large subunit of ribulose bisphosphate carboxylase/oxygenase (rubisco) was duplicated in the genome by a targeted insertion of a 3'-truncated gene copy into the psb a-i locus. both rbcl genes, in the psb a-i region and at the rbc locus, were non-functional; the former due to the 3' truncation, and the latter due ...19921465099
conservation of the photosynthesis gene cluster in rhodospirillum centenum.intraspecies and intergenus complementation analysis were utilized to demonstrate that photosynthesis genes are clustered in distantly related purple photosynthetic bacteria. specifically, we show that the linkage order for genes involved in bacteriochlorophyll and carotenoid biosynthesis in rhodospirillum centenum are arranged essentially as in rhodobacter capsulatus and rhodobacter sphaeroides. in addition, the location and relative distance observed between the puf and puh operons which encod ...19921447976
[the evolutionary changes in the amino acid sequences and properties of the atp-synthase in chloroplasts, mitochondria and bacteria].studies have been made on atpase from chloroplasts, cyanobacteria and mitochondria of higher plants and animals. no intraspecies and interspecies variability of chloroplast and mitochondrial atpase was found with respect to ph optimum of the activity, to specificity to cations as substrate components, to sensitivity to stimulating and inhibiting anions and ethanol, to optimal stimulating ethanol concentration. intergenus variation of these properties of atpase from chloroplasts, plant mitochondr ...19921441793
surface-enhanced raman scattering spectroscopy of photosynthetic membranes and complexes. 19921435308
prokaryotic triterpenoids: o-alpha-d-glucuronopyranosyl bacteriohopanetetrol, a novel hopanoid from the bacterium rhodospirillum rubrum.a novel hopanoid bearing a glucuronopyranosyl residue linked via an alpha-glycosidic bond to the hydroxyl group of c-35 in bacteriohopanetetrol was isolated, from the type strain of rhodospirillum rubrum as well as from a mutant lacking blue carotenoid.19921417769
in vitro activation of dinitrogenase reductase from the cyanobacterium anabaena variabilis (atcc 29413).nitrogenase of the heterocystous cyanobacterium anabaena variabilis was inactivated in vivo (s. reich, h. almon, and p. böger, fems microbiol. lett. 34:53-56, 1986). partially purified and modified (inactivated) dinitrogenase reductase (fe-protein) of such cells was reactivated by isolated membrane fractions of a. variabilis or of rhodospirillum rubrum, and acetylene reduction was measured. reactivation requires atp, mg2+, and mn2+. the activating principle is localized in the heterocyst and was ...19921400166
tentoxin sensitivity of chloroplasts determined by codon 83 of beta subunit of proton-atpase.tentoxin is a naturally occurring phytotoxic peptide that causes seedling chlorosis and arrests growth in sensitive plants and algae. in vitro, it inhibits activity of the beta subunit of the plastid proton-adenosine triphosphatase (atpase) from sensitive species. plastid atpb genes from six closely related, tentoxin-sensitive or -resistant nicotiana species differ at codon 83, according to their response to the toxin: glutamate correlated with resistance and aspartate correlated with sensitivit ...19921387730
nucleotide sequence of cdna clones encoding the beta subunit of mitochondrial atp synthase from the green alga chlamydomonas reinhardtii: the precursor protein encoded by the cdna contains both an n-terminal presequence and a c-terminal extension.cdna and genomic clones encoding the beta subunit of mitochondrial atp synthase from chlamydomonas reinhardtii have been isolated using heterologous dna probes from the photosynthetic bacterium rhodospirillum rubrum. the protein encoded by the cdna is 79-83% identical to corresponding proteins from higher-plant and mammalian mitochondria, and 75% identical to the r. rubrum protein. it contains both an n-terminal presequence and a unique c-terminal extension. the presequence, which is the first m ...19921386535
purified chaperonin 60 (groel) interacts with the nonnative states of a multitude of escherichia coli vitro experiments employing the soluble proteins from escherichia coli reveal that about half of them, in their unfolded or partially folded states, but not in their native states, can form stable binary complexes with chaperonin 60 (groel). these complexes can be isolated by gel filtration chromatography and are efficiently discharged upon the addition of mg.atp. binary complex formation is substantially reduced if chaperonin 60 is presaturated with rubisco-i, the folding intermediate of rub ...19921363913
conformational states of ribulosebisphosphate carboxylase and their interaction with chaperonin 60.conformational states of ribulosebisphosphate carboxylase (rubisco) from rhodospirillum rubrum were examined by far-uv circular dichroism (cd), tryptophan fluorescence, and 1-anilino-naphthalenesulfonate (ans) binding. at ph 2 and low ionic strength (i = 0.01), rubisco adopts an unfolded, monomeric conformation (ua1 state) as judged by far-uv cd and tryptophan fluorescence. as with other acid-unfolded proteins [goto, y., calciano, l. j., & fink, a. l. (1990) proc. natl. acad. sci. u.s.a. 87, 573 ...19921348956
evidence of an essential carboxyl residue in membrane-bound pyrophosphatase of rhodospirillum rubrum.chemical modifications with water-soluble carbodiimides (edc and cmc) were performed to elucidate whether some carboxyl residues are involved in the catalytic activity of membrane-bound pyrophosphatase of rhodospirillum rubrum. edc and cmc cause a loss of hydrolytic activity following pseudo-first-order kinetics up to 10 min of reaction. the enzyme was completely protected against edc inhibition by ppi or mg2+, whereas ppi or mg2+ gave partial protection against cmc inactivation. mg-ppi protecte ...19921334073
isolation and characterisation of a functional alpha beta heterodimer from the atp synthase of rhodospirillum alpha beta heterodimer of the f1-atpase of rhodospirillum rubrum was isolated by extraction of chromatophores with licl. each alpha beta heterodimer contains one tightly bound adp, which is released upon removal of medium mg2+. the dimer can be reversibly dissociated by removal of mg(2+)-ions. the alpha beta heterodimer restores both atp-synthetic and -hydrolytic activities to licl-treated chromatophores, saturation being achieved at approximately 2 mmol alpha beta.mol bchl-1. the heterodimer ...19921327870
three-dimensional structure of ferricytochrome c' from rhodospirillum rubrum at 2.8 a resolution.the structure of ferricytochrome c' extracted from rhodospirillum rubrum has been determined by the x-ray crystallographic method. crystals in hexagonal space group p6(1), with unit-cell dimensions a = b = 51.72 a and c = 155.49 a, contain one dimer molecule composed of chemically identical polypeptide chains (monomer i and monomer ii) per asymmetric unit. an electron density map has been calculated at a resolution of 2.8 a by the multiple isomorphous replacement method using four-circle diffrac ...19921316891
mg2+ is an essential activator of hydrolytic activity of membrane-bound pyrophosphatase of rhodospirillum rubrum.the substrate for the hydrolytic activity of membrane-bound pyrophosphatase is the pp(i)-mg2+ complex. the enzyme has no activity when the free mg2+ concentration is lower than 10 microm (at 0.5 mm-pp(i)-mg2+), and therefore free mg2+ is an essential activator of the hydrolytic activity. the km for the substrate changes in response to variation in free mg2+ concentration, from 10.25 to 0.6 mm when free mg2+ is increased from 0.03 to 1.0 mm respectively. the km for mg2+ depends on the substrate c ...19921315519
absolute configuration of 3-hydroxy fatty acids present in lipopolysaccharides from various bacterial groups.the absolute configuration of 3-hydroxy fatty acids has been studied, which are present in the lipopolysaccharides of the following bacteria: phodopseudomonas gelatinosa, rh. viridis, rhodospirillum tenue, chromobacterium violaceum, pseudomonas aeruginosa, bordetella pertussis, vibrio metchnikovii, vibrio cholerae, salmonella spp., escherichia coli, shigella flexneri, proteus mirabilis, yersinia enterocolitica and fusobacterium nucleatum. the 3-hydroxy acids were liberated by strong alkaline hyd ...19761278168
[bacteriochlorophyll fluorescence changes related to the bacteriopheophytin photoreduction in the chromatophores of purple sulfur bacteria].it is shown that illumination of chromatophores of sulfur bacterium chromatium minutissimum at eh of the medium --200 mv divided by --620 mv (when the photooxidation of pigment p890 is completely inhibited) induces a decrease in bacteriochlorophyll fluorescence yield, reversible in the dark. under these conditions a reversible photoreduction of bacteriopheophytin is detected (bleaching of absorption bands at 543 and 760 nm and development of a band at 650 nm), which is accompanied by a blue shif ...19761024595
base competition of dna isolated from thiobacillus ferrooxidans grown on different substrates.the present study indicates some anomalies with respect to the dna base composition of thiobacillus ferrooxidans when it is cultured on different substrates. the % gc of the dna of this bacterium has been calculated by three different methods (melting temperature, cscl density gradient centrifugation and ultra-violet absorbancy ratios) using escherichia coli and rhodospirillum rubrum as references. the main values for t. ferrooxidans grown on ferrous iron, chalcopyrite and lead sulfide concentra ...1976981743
interrelationships among excited states in bacterial reaction centers. 1976830043
[regulation of citrate synthese in bacteria: comparison of the action of various effectors on the enzymes of rhodospirillum rurbum and bacillus stearothermophilus].a comparative study of the citrate synthases purified from the facultatively photosynthetic bacterium rhodospirillum rubrum (gram negative) and the thermophile bacillus stearothermophilus (gram positive) was made. the citrate synthase from r. rubrum was activated by kcl (6-fold at 0.1 m kcl) and, less effectively, by nacl and nh4cl. its molecular weight was about 300,000. the enzyme was strongly inhibited by nadh, and this inhibition was counteracted by amp. the citrate synthase from b. stearoth ...1976826987
naphxhylmercaptobenzoquinone, a new inhibitor of photophosphorylation in rhodospirillum rubrum chromatophores at the level of ubiquinone. 1976826250
reconstitution of biological molecular generators of electric current. bacteriochlorophyll and plant chlorophyll complexes.1. electric generation by bacteriochlorophyll reaction center complexes from rhodospirillum rubrum and by photosystem i complexes from pea chloroplasts has been studied. 2. the methods for the proteoliposome reconstitution from azolectin and bacteriochlorophyll- or plant chlorophyll-containing protein complexes have been elaborated. light-dependent electric responses of the proteoliposomes were detected using (a) phenyldicarbaundecarborane anion (pcb-) probe and (b) direct measurement by a voltm ...1976825514
activating factor for the iron protein of nitrogenase from rhodospirillum isolated from rhodospirillum rubrum, the iron protein of nitrogenase has little or no activity. it can be activated by incubating it with a trypsin-sensitive, oxygen-labile component (activating factor) plus adenosine triphosphate and a divalent metal ion. after activation, the iron protein retains its nitrogenase activity when the activating factor is removed.1976824729
functional and structural differences between photosynthetic and heterotrophic rhodospirillum rubrum ribosomes and s-100 fractions.cell-free, protein-synthesizing activity has been tested by using various combinations of the s-100 and ribosome fractions prepared from photosynthetic and heterotrophic rhodospirillum rubrum. the photosynthetic ribosomes are highly active when combined with either the photosynthetic or the heterotrophic s-100 fractions, whereas the heterotrophic ribosomes are active only when combined with the photosynthetic s-100 fraction. addition of a photosynthetic pigment-containing fraction to the homolog ...1976824038
triplet states of bacteriochlorophyll and carotenoids in chromatophores of photosynthetic bacteria.chromatophores from photosynthetic bacteria were excited with flashes lasting approx. 15 ns. transient optical absorbance changes not associated with the photochemical electron-transfer reactions were interpreted as reflecting the conversion of bacteriochlorophyll or carotenoids into triplet states. triplet states of various carotenoids were detected in five strains of bacteria; triplet states of bacteriochlorophyll, in two strains that lack carotenoids. triplet states of antenna pigments could ...1976823977
inhibition of d-ribulose 1,5-bisphosphate carboxylase by pyridoxal 5'-phosphate. 1976823940
preparation and properties of bacterial chromatophores entrapped in polyacrylamide.the immobilization of rhodospirillum rubrum chromatophores was successfully performed by entrapping them in polyacrylamide. their photophosphorylating activity was about 40% of native chromatophores. the temperature and ph optima for immobilized chromatophores were similar to the native photosynthetic apparatus and kinetic parameters showed that the rate of photophosphorylation in polyacrylamide particles was diffusion controlled. light penetration of the gel particles was not a limiting paramet ...1976822898
photosynthetic regeneration of atp using bacterial chromatophores.we have demonstrated the use of bacterial chromatophores for the continuous photosynthetic regeneration of atp from adp in an ultrafiltration reactor. biphasic kinetics of the degradation of chromatophore activity are described. using chromatophores in combination with the enzyme adenylate kinase, we have also demonstrated continuous regeneration of atp from amp.1976822897
photodichroic studies of the photoreaction center from rhodospirillum rubrum. i. attribution of p870 to two non parallel dipoles.a randomly oriented sample of photoreaction center prepared from rhodospirillum rubrum was excited at 77 degrees k by an actinic linearly polarized light of 870 nm. under such conditions, only those chromophores with components of their absorption dipoles oriented parallel to the polarization of the actinic light are bleached. the change in absorbance at 900 nm of this photoselected sample was observed while varying the angle of polarization of a weak measuring light. the polarization of the abs ...1976822873
a possible physiological function of the oxygen-photoreducing system of rhodospirillum rubrum.anaerobic suspensions of rhodospirillum rubrum cells which had been grown in the dark under low oxygen tension showed only a small increase of their atp content when illuminated for 30 s. the same suspensions failed to start immediate growth in the light. both high light-induced atp levels and immediate phototrophic growth were elicited by small amounts of oxygen which were insufficient by themselves to raise the atp levels or to support growth in the dark. the oxygen requirement for growth disa ...1976822793
structural order in chromatophore membranes of rhodospirillum rubrum. 1976822349
effects of 4-[beta-(diethylamino)-ethoxy]-benzophenone upon carotenogenesis in rhodospirillum rubrum.carotenoid production was determined in illuminated anaerobically maintained cultures of rhodospirillum rubrum in media with and without 4-[beta-(diethylamino)-ethoxy]-benzophenone. in treated cultures, lycopene--which normally is not produced by r. rubrum--accumulated as the predominant pigment, and total carotenoids increased five- to sixfold.1976821916
novel nucleotides from e. coli isolated and partially characterized. 1976821487
membranes of rhodospirillum rubrum: physicochemical properties of chromatophore fractions isolated from osmotically and mechanically disrupted cells.isolation of highly purified membrane fractions from phototrophically grown rhodospirillum rubrum was achieved by velocity and isopyknic sedimentation under carefully controlled ionic conditions. bacteriochlorophyll-rich and succinic dehydrogenase-rich chromatophores that were essentially devoid of contamination by non-chromatophore protein were separated from a denser fraction in extracts disrupted in a french pressure cell. highly purified chromatophores and a nearly photopigment-free envelope ...1976820690
membranes of rhodospirillum rubrum: isolation and physicochemical properties of membranes from aerobically grown cells.highly purified preparations of cytoplasmic and outer membrane were isolated from aerobically grown rhodospirillum rubrum lysed by sequential treatment with lysozyme, ethylenediaminetetraacetate, and brij 58. the membranes were resolved and separated from other cellular constitutents by a combination of velocity and isopyknic sedimentation in sucrose density gradients. on the basis of their appearance in electron micrographs and their protein profiles in sodium dodecyl sulfate-polyacrylamide gel ...1976820689
measurement of transmembrane potentials in rhodospirillum rubrum chromatophores with an oxacarbocyanine dye.the fluorescent dye 3,3-dipentyloxacarbocyanine (occ) can be used as a fluorescence probe to measure transmembrane potentials across rhodospirillum rubrum chromatophore membranes. a reversible fluorescence increase is observed in the light which is sensitive to inhibitors, permeable ions and uncouplers. partial interchangeability between the electrical potential and the proton concentration gradient has been demonstrated by measurement of the fluorescence increase with occ and the fluorescence q ...1976820380
phototactic response of aerobically cultivated rhodospirillum rubrum.motile cells of aerobically cultivated rhodospirillum rubrum, containing no detectable bacteriochlorophyll, assembled at a spot of strong light projected through a dark-field condenser. far-red light was not effective, indicating that bacteriochlorophyll and thus photosynthetic metabolism was not responsible for the phenomenon. bacteria moving towards the centre of the light spot changed direction less frequently than those moving towards the margin. they also responded to temporal changes in th ...1976819621
motility in normal and filamentous forms of rhodospirillum suitable choice of medium, rhodospirillum rubrum has been grown both in normal (length 2 mum) and filamentous (length up to 60 mum) forms. both forms were highly motile, and negatively-stained preparations showed bipolar flagellated cells, with an average of seven flagella at each pole. motion consisted of a series of runs and tumbles, the ditribution of run time-lengths being poissonian. both forms tumbled in response to dark shock and showed negative chemotaxis to oxygen. the observation th ...1976819618
[reconstruction of the function of membrane potential formation by isolated pigment-protein complexes of rhodospirillum rubrum].the pigment-protein complexes, containing the photosynthetic reaction centers and chlorophyll antenna, were isolated from non-sulfur purple bacteria rhodospirillum rubrum, by use of cholate. absorption spectra and quantum yield of photo-oxidation of bacteriochlorophyll p870 of complexes were similar to those of chromatophores. the procedure of reconstitution of proteoliposomes from phospholipids and complexes was proposed. the proteoliposomes incubated with coq6 and tmpd upon illumination are ge ...1976819043
[purification and properties of rhodospirillum rubrum nadp-reductase].rhodospirillum rubrum cell extracts have active nadp-reductase capable of catalyzing the diaphorase reaction in the presence of methyl viologene or benzyl viologene and nadph-generating system. the greater part of nadp-reductase is localized in the soluble fraction of destroyed cells (90-10(3) g; 90 min). the purified preparation of nadp-reductase was found to contain 6 proteins, 4-5 of them possessing diaphorase activity. partially purified nadp-reductase preparation with a period of half-inact ...1976819042
early formation of intracytoplasmic membranes in rhodospillum rubrum.cytoplasmic and intracytoplasmic membranes were isolated from rhodospirillum rubrum by equilibrium sucrose density gradient centrifugation. immediately after the induction of photosynthetically active intracytoplasmic membranes, bacteriochlorophyll is incorporated predominantly into the cytoplasmic membrane. with increasing pigment concentrations the newly arising intracytoplasmic membranes become sites of preferential bacteriochlorophyll incorporation. during this process the infrared absorptio ...1976819036
[acid-soluble nucleotides of the phototrophic bacterium rhodospirillum rubrum during growth in light and in darkness].the content of acid-soluble nucleotides was different in the cells of non-sulphur purple bacterium rhodospirillum rubrum, growing phototrophically under anaerobic conditions and aerobically under conditions of heterotrophic nutrition. the cells of the culture growing in the darkness contained more adenylic and guanylic nucleotides, and the total of reduced and oxidized nadp. the cells of the culture growing in the light contained more fmn. the cells of the "light" and "dark" cultures contained g ...1975818480
[phototransformations of bacteriopheophytin in reaction centers of rhodospirillum rubrum and crhomatium minutissimum]. 1976817883
triplet states of carotenoids from photosynthetic bacteria studied by nanosecond ultraviolet and electron pulse irradiation. 1976817340
a novel short-lived emission from the photosynthetic bacterium rhodospirillum rubrum. 1976816674
cell-free, protein-synthesizing system of photosynthetic and heterotrophic rhodospirillum active in vitro protein-synthesizing system has been developed from rhodospirillum rubrum grown under either photosynthetic or heterotrophic conditions. a protease activity has been found in both of these systems, and this activity can be readily inactivated by treating the cells with kcl and phenylmethyl sulfonylfluoride. the difference in protein-synthesizing activity between the photosynthetic and the heterotrophic systems has been tested in regard to the requirement of various chemicals a ...1976816440
properties of ribonucleic acids from photosynthetic and heterotrophic rhodospirillum rubrum.rifampicin causes an initial rapid breakdown of about 30% of the pulse-labeled rna in both photosynthetic and heterotrophic rhodospirillum rubrum. an additional degradation of rna has been observed in the heterotrophic, but not in the photosynthetic cells at a later stage of rifampicin treatment. this secondary rna degradation is probably caused by breakdown of ribosomal rna, especially of the 23s species, as shown by polyacrylamide gel electrophoresis analyses. no qualitative difference between ...1976816437
new experimental approach to the estimation of rate of electron transfer from the primary to secondary acceptors in the photosynthetic electron transport chain of purple bacteria.a method for calculating the rate constant (ka1a2) for the oxidation of the primary electron acceptor (a1) by the secondary one (a2) in the photosynthetic electron transport chain of purple bacteria is proposed. the method is based on the analysis of the dark recovery kinetics of reaction centre bacteriochlorophyll (p) following its oxidation by a short single laser pulse at a high oxidation-reduction potential of the medium. it is shown that in ectothiorhodospira shaposhnikovii there is little ...1976816385
unidirectional inhibition of phosphoenolpyruvate carboxykinase from rhodospirillum rubrum by atp.the kinetic and regulatory properties of partially purified phosphoenolpyruvate (pep) carboxykinase (ec from rhodospirillum rubrum were studied. the enzyme was active with guanosine- and inosinephosphates and must thus be classified as gtp (itp): oxaloacetate carboxylase (transphosphorylating.) in the direction of oxaloacetate-foramtion, the enzyme was strongly inhibited by atp (ki = 0.03 mm). itp, utp, ctp, and gtp were less inhibitory. the inhibition was competitive with respect to ...1976816325
[technique for the determination of the quantum yield of the primary process in the course of photosynthesis energy transformation. iii. experimental data obtained for different photosynthetic organisms].a relative method in two modifications has been developed for determination of the quantum yield of primary photosynthesis energy conversion. the purple bacteria e. chaposhnikovii and chr. minutissimum, r. rubrum chromatophores, cell extracts of e. shaposhnikovii, rps. spheroides strains ga and r-26, pigment-protein complexes from green bacterium chl. limicola and light subchloroplast particles, enriched in the photosystem i, were investigated. the quantum yields for all these objects were shown ...1975815784
[theoretical study of the kinetics of dark reduction of photochemically oxidized bacteriochlorophyll in the reaction center of rhodospirillum rubrum chromatophores].it is shown from the results of theoretical study that the scheme involving two successive interacting components of the pool of secondary acceptors shows the biexponential character of the kinetics of dark reduction of the pigment of p870 observed in the experiment. the velocity constants of the electron transport reactions considered are evaluated.1976814933
lipoic acid content of escherichia coli and other microorganisms.a mutant strain of escherichia coli k-12 requiring lipoic acid. w1485lip 2 (atcc 25645), was used to develop a turbidimetric assay for lipoic acid and a polarographic assay based on the oxidation of pyruvate by suspensions of lipoic acid-deficient organisms. the turbidmetric assay was more sensitive with a working range equivalent to 0.2-2.0 ng of dl-alpha-lipoic acid compared with 5-50 ng for the polarographic method. the mutant responded equally to racemic mixtures of alpha-lipoic acid, beta-l ...1975814874
primary reactions in photosynthesis. 1975814555
formation of beta-methylmalate and its conversion to citramalate in rhodospirillum rubrum.using a cell-free extract of rhodospirillum rubrum, studies were made of the condensation reaction between propionyl-coa and glyoxylate. when [14c]propionate was incubated with the extract in the presence of glyoxylate, atp, coa, mg2+, and mn2+, radioactivity was incorporated into several compounds. two of the main products were characterized as citramalate (cma) and erythro-beta-methylmalate (erythro-mma) on the basis of their behavior compared with authentic samples of cma and erythro-mma in t ...1975814116
[reversible photooxidation of bacteriochlorophylls a and b in aqueous solutions of detergents]. 1975813982
characterization of two cell-envelope fractions from chemotrophically grown rhodospirillum rubrum.two cell-envelope fractions were isolated from chemotrophically grown cells of rhodospirillum rubrum. on the basis of electron-microscopic investigations, chemical analysis, distribution of components involved in respiration, and poly-acrylamide gel electrophoresis, the heavy fraction (rho20 = 1.246 g per cm3) was identified as cell-wall, and the light fraction (rho = 1.145 g per cm3) as cyto-plasmic-membrane fragments. electron micrographs showed cell-wall fragments as open structures while cyt ...1975813575
possible role of firmly bound atp in the energy transduction of photosynthetic membranes.chromatophores of rhodospirillum rubrum and spinach chloroplasts contain firmly bound atp that is rapidly labeled along with adp in the presence of 32pi and endogenous nucleotides. the labeling is not entirely dependent on light. in chloroplasts three types of bound atp can be defined methodologically by their extraction properties: buffer-soluble; acid-soluble; and sds-soluble or firmly bound atp. extensive washing of the chloroplasts does reduce buffer-soluble but not acid-soluble and firmly b ...1975813067
ultrastructural deformation studies on biological membranes.the ultrastructural deformation technique has been used to study various membranes, including several claimed to show subunit structure. with localized deformation fibers ca. 100-300 a in diameter and up to 4,000 a long were found extending across the cracks parallel to the draw direction in all membranes. lipid extraction and proteolytic enzyme (papain) treatment of membranes has shown that the fibers are protein in nature. deformation of membranes while still wet showed no significant change i ...1975813066
regulation of nitrogenase synthesis in intact cells of rhodospirillum rubrum: inactivation of nitrogen fixation by ammonia, l-glutamine and l-asparagine.the synthesis of nitrogenase by intact cells of rhodospirillum rubrum was repressed in n-free media supplemented with l-glutamine or l-asparagine, but was unaffected by the presence of l-glutamate, l-aspartate or l-histidine. specific activities attained by cultures in supplemented media maintained under ar-co2 were 2 to 3 times higher than those in n-free medium under n2-co2. a loss in total activity occurred both in cultures growing with n2 after maximum activity had been reached, and in cultu ...1975811763
carotenoid triplet states in reaction centers from rhodopseudomonas sphaeroides and rhodospirillum rubrum.purified photochemical reaction centers from three strains of rhodopseudomonas sphaeroides and two of rhodospirillium rubrum were reduced with na2s2o4 so as to block their photochemical electron transfer reactions. they then were excited with flashes lasting 5-30 ns. in all cases, absorbance measurements showed that the flash caused the immediate formation of a transient state (pf) which had been detected previously in reaction centers from rps. sphaeroides strain r26. previous work has shown th ...1975811259
light-dependent atp formation in a non-phototrophic mutant of rhodospirillum rubrum deficient in oxygen photoreduction. 1975810144
[effect of temperature on the dark reduction of photooxidized bacteriochlorophyll p870 in rhodospirillum rubrum photosynthetic bacteria]. 1975809066
[relation of chloroplast and chromatophore fluorescence yield to the state of the reaction centers]. 1975807465
[change in the absorption spectra of carotenoids in dry films of rhodospirillum rubrum chromatophores in an external electric field].electrochromic spectra of carotenoids in dried films of chromatophores of rhodospirillum rubrum in 450-600 nm region are obtained. their good agreement with the photoinduced absorption changes of the same chromatophores under different conditions is shown.1975807260
ribulose-diphosphate carboxylase from the hydrogen bacteria and rhodospirillum rubrum. 1975805894
ribulose-1, 5-diphosphate carboxylase from rhadospirillum rubrum. 1975805893
carotenoid and merocyanine probes in chromatophore membranes. 1975804940
[action spectra of photosynthesis and liberation of hydrogen in bacteria, algae and higher plants]. 1975804393
[regulation of nitrogenase biosynthesis in microorganisms]. 1975803994
Displaying items 1901 - 2000 of 2252