| sn-glycerol-3-phosphate acyltransferase activity in particulate preparations from anaerobic, light-grown cells of rhodopseudomonas spheroides. involvement of acyl thiolester derivatives of acyl carrier protein in the synthesis of complex lipids. | crude particulate preparations obtained from anaerobic, light-grown cells of rhodopseudomonas spheroides have been shown to possess a significant level of sn-glycerol-3-phosphate acyltransferase (ec 2.3.1.15) activity. in contrast to the enzyme from escherichia coli, the r. spheroides glycerophosphate acyltransferase has a high specificity for acyl thiolester derivatives of acyl carrier protein (acp) as acyl donors for the reaction. only limited , nonlinear glycerophosphate incorporation into li ... | 1975 | 387 |
| the primary acceptor of bacterial photosynthesis: its operating midpoint potential? | | 1976 | 4013 |
| properties of the flash-induced proton binding encountered in membranes of rhodopseudomonas sphaeroides: a functional pk on the ubisemiquinone? | | 1976 | 4014 |
| ubiquinone-cytochrome b electron and proton transfer: a functional pk on cytochrome b50 in rhodopseudomonas sphaeroides membranes. | | 1976 | 4015 |
| control of 5-aminolaevulinate synthetase activity in rhodopseudomonas spheroides. | rhodopseudomonas spheroides can grow in a defined medium with either light or oxygen as an energy source. cells grown anaerobically or at very low oxygen tensions are rich in the photosynthetic pigment bacteriochlorophyll, whereas this pigment is virtually absent in cells grown under high oxygen tensions. aminolaevulinate synthetase, the first enzyme on the pathway to bacteriochlorophyll, appears to play an important role in the control of bacteriochlorophyll synthesis. thus, the enzyme has a hi ... | 1976 | 4844 |
| ph dependence of the oxidation-reduction potential of cytochrome c2. | the ph dependence of the spectra and of the oxidation-reduction potential of three cytochromes c2, from rhodopseudomonas capsulata, rhodopseudomonas sphaeroides and rhodomicrobium vannielii, were studied. a single alkaline pk was observed for the spectral changes in all three ferricytochromes. in rps. capsulata cytochrome c2 this spectroscopic pk corresponds to the pk observed in the dependence of oxidation-reduction potential on ph. for the other two cytochromes the oxidation-reduction potentia ... | 1976 | 6058 |
| fermentation of pyruvate by 7 species of phototrophic purple bacteria. | the dark, anaerobic fermentation of pyruvate under growth conditions was examined with the following species of phototrophic purple bacteria: rhodospirillum rubrum strains ha and s1, rhodopseudomonas gelatinosa strain 2150, rhodopseudomonas acidophila strain 7050, rhodopseudomonas palustris strain atcc 17001, rhodopseudomonas capsulata strains kb1 and 6950, rhodopseudomonas sphaeroides strain atcc 17023, and chromatium vinosum strain d. fermentation balances were established for all experiments. ... | 1976 | 12621 |
| the ph dependence of the oxidation-reduction midpoint potential of cytochromes c2 in vivo. | a recent report by pettigrew et al. biochim, biophys. acta 430, (1976), 197-208 has examined the ph dependence of the oxidation-reduction midpoint potential of cytochromes c2 in vitro. in media of low ionic strength, these workers identified several pks on the oxidized forms of the cytochromes, and in some cases there were also pks on the reduced species. in this work we examine the ph dependence of the midpoint potentials of the cytochromes in situ, attached to the chromatophore membrane. under ... | 1977 | 14684 |
| proton pumps in bacterial photosynthesis. | | 1977 | 20371 |
| kinetics and stoichiometry of proton binding in phodopseudomonas sphaeroides chromatophores. | | 1977 | 23313 |
| the electrochemical proton gradient generated by light in membrane vesicles and chromatophores from rhodopseudomonas sphaeroides. | | 1978 | 25184 |
| equilibrium and disequilibrium in the ubiquinone-cytochrome b-c2 oxidoreductase or rhodopseudomonas sphaeroides. | | 1978 | 27385 |
| the dimerization of ferrihaems. iii. equilibrium and kinetic studies on the dimerization of coproferrihaem. | spectrophotometric studies on the behaviour of coproferrihaem in aqueous solution showed that, in the ph range 6.66--8.04, a dimerization process occurs according to the equation 2 monomer k in equilibrium dimer + h+ the value of k, the ph-independent dimerization constant, was found to be 2.10 . 10(-3), signifying that coproferrihaem shows the least tendency to dimerize of any ferrihaem so far investigated. forward and reverse rate constants for the dimerization process have been determined by ... | 1978 | 31193 |
| response of 9-aminoacridine fluorescence to transmembrane ph-gradients in chromatophores from rhodopseudomonas sphaeroides. | | 1978 | 33044 |
| factors controlling the binding of two protons per electron transferred through the ubiquinone and cytochrome b/c2 segment of rhodopseudomonas sphaeroides chromatophores. | 1. on every turnover, 2.0 protons can be bound by the membrane for each single electron moving through the q-b/c2 oxidoreductase. 2. one proton (h+ii) binding reaction is, and one (h+i) is not, sensitive to antimycin. 3. the redox states of electron transfer components other than the proton binding agents can affect both the rate of proton uptake and the apparent pk values on the agents binding the protons. 4. the presence of valinomycin under certain well-defined conditions can strongly influen ... | 1979 | 36140 |
| spectroscopic and kinetic properties of the transient intermediate acceptor in reaction centers of rhodopseudomonas sphaeroides. | the photoreductive trapping of the transient, intermediate acceptor, i-, in purified reaction centers of rhodopseudomonas sphaeroides r-26 was investigated for different external conditions. the optical spectrum of i- was found to be similar to that reported for other systems by shuvalov and klimov ((1976) biochim. biophys. acta 400, 587--599) and tiede et al. (p.m. tiede, r.c. prince, g.h. reed and p.l. dutton (1976) febs lett. 65, 301--304). the optical changes of i- showed characteristics of ... | 1979 | 36906 |
| light-induced, carrier-mediated transport of tetracycline by rhodopseudomonas sphaeroides. | tetracycline accumulation by the phototrophic bacterium rhodopseudomonas sphaeroides has been studied, using the fluorescence properties of the antibiotic and measuring uptake of [7- 3h]tetracycline. accumulation was carrier mediated, with a km of approximately 300 micronm. efflux also appeared to be carried mediated, with a km of 25 mm. chlorotetracycline competitively inhibited tetracycline transport. the transport was energy dependent. efflux occurred during the influx process, and an energy- ... | 1979 | 37230 |
| effect of surface potential on the intramembrane electrical field measured with carotenoid spectral shift in chromatophores from rhodopseudomonas sphaeroides. | changes in the surface potential, the electrical potential difference between the membrane surface and the bulk aqueous phase were measured with the carotenoid spectral shift which indicates the change of electrical field in the membrane. chromatophores were prepared from a non-sulfur purple bacterium, rhodopseudomonas sphaeroides, in a low-salt buffer. surface potential was changed by addition of salt or by ph jump as predicted by the gouy-chapman diffuse double layer theory. when a salf was ad ... | 1979 | 37904 |
| electron and proton transport in the ubiquinone cytochrome b-c2 oxidoreductase of rhodopseudomonas sphaeroides. patterns of binding and inhibition by antimycin. | the effect of antimycin on the ubiquinone cytochrome b-c2 (q b-c2) oxidoreductase of the photosynthetic bacterium rhodopseudomonas sphaeroides has been studied under controlled oxidation-reduction potential (eh) conditions by equilibrium measurements and by rapid kinetic analysis of single turnover flash.induced electron and proton translocations. 1. antimycin shifts the alpha-band of ferro b50 (lambda max 560 nm) by 1 to 2 nm toward the red but has no apparent effect on the equilibrium oxidatio ... | 1979 | 38253 |
| equilibrium and kinetic measurements of the redox potentials of cytochromes c2 in vitro and in vivo. | the equilibrium oxidation-reduction mipoint potential (em) of isolated rhodopseudomonas sphaeroides cytochrome c2 exhibits a ph-dependent behavior which can be ascribed to a pk on the oxidized form at ph 8.0 (pettigrew et al. (1975) biochim. biophys. acta 430, 197-208). however, as with mammalian cytochrome c (brandt, k.g. parks, p.c., czerlinski, g.h. and hess, g.p. (1966) j. biol. chem. 241, 4180-4185) this pk can more properly be attributed to the combination of a pk beyond ph 11, and a slow ... | 1979 | 39597 |
| the purification of glutamine synthetase from azotobacter and other procaryotes by blue sepharose chromatography. | we report the facile purification of glutamine synthetase (l-glutamate: ammonia ligase (adenosine 5'-diphosphate-forming), ec 6.3.1.2) in both the adenylylated and unadenylylated form, from azotobacter vinelandii atcc 12837. a general affinity column, which used as an affinity ligand reactive blue 2 dye (cibacron blue) covalently linked to agarose, was employed as an efficient first step of purification. further purification to electrophoretic homogeneity employed deae-cellulose chromatography a ... | 1979 | 39606 |
| electron acceptors of bacterial photosynthetic reaction centers. ii. h+ binding coupled to secondary electron transfer in the quinone acceptor complex. | the photoreduction of ubiquinone in the electron acceptor complex (qiqii) of photosynthetic reaction centers from rhodopseudomonas sphaeroides, r26, was studied in a series of short, saturating flashes. the specific involvement of h+ in the reduction was revealed by the ph dependence of the electron transfer events and by net h+ binding during the formation of ubiquinol, which requires two turnovers of the photochemical act. on the first flash qii receives an electron via qi to form a stable ubi ... | 1979 | 41574 |
| characterization of antiserum directed against form ii ribulose 1,5-bisphosphate carboxylase from rhodopseudomonas sphaeroides. | antiserum directed against form ii ribulose 1,5-bisphosphate carboxylase from rhodopseudomonas sphaeroides showed no cross-reactivity towards the form i enzyme as evidenced by a lack of immunopreciptation. in addition, this antiserum failed to inhibit form i enzymatic activity. | 1977 | 70425 |
| bacteriochlorophyll fluorescence of purple bacteria at low redox potentials. the relationship between reaction center triplet yield and the emission yield. | this work describes fluorescence yield measurements in suspensions of strains of rhodospirillum rubrum and rhodopseudomonas sphaeroides in which the iron . quinone complex (x) was chemically reduced (state [pix-]; p is the reaction center bacteriochlorophyll dimer, i is the long wavelength bacteriopheophytin), and compares these with the fluorescence observed when all the traps are open (state [pix]) and with the fluorescence observed when all the traps are closed (state [p+ix]). at 77 k the amp ... | 1978 | 96854 |
| flash-induced changes in the in vivo bacteriochlorophyll fluorescence yield at low temperatures and low redox potentials in carotenoid-containing strains of photosynthetic bacteria. | the changes in the in vivo bacteriochlorophyll fluorescence induced by a xenon flash at low temperatures (77--200 k) with the "primary" acceptor x chemically prereduced have been examined in whole cells of several species of photosynthetic bacteria which contain carotenoids absorbing in the visible part of the absorption spectrum. two groups of species with different behaviour could be distinguished. in both cases a flash-induced rise of the fluorescence yield was observed with x prereduced at 7 ... | 1978 | 96856 |
| dichroism of bacteriochlorophyll in chromatophores of photosynthetic bacteria. | the dichroism was measured in films of air-dried and, consequently, flattened chromatophores of chromatium vinosum, rhodopseudomonas sphaeroides and rhodospirillum rubrum. the values (deltaa/a) of dichroism in c. vinosum were found to be -1.05 at 590 nm and 0.75 in the near infrared region. the values of dichroism in r. sphaeroides were -0.70 at 590 nm and 0.80 at 870 nm. the values of dichroism in r. rubrum were -1.45 at 590 nm and 0.97 at 870 nm. | 1978 | 97281 |
| on the state of carotenoids bound to reaction centers of photosynthetic bacteria: a resonance raman study. | the carotenoids bound to reaction centers of wild, ga and gic strains of rhodopseudomonas spheroides, of rhodospirrillum rubrum, strain s1 and of rhodopseudomonas viridis, yield very similar, but unusual resonance raman spectra. through a comparison with resonance raman spectra of 15,15'-cis-beta-carotene, these carotenoids are shown to assume cis conformations, while the corresponding chromatophores contain all-trans forms only. these cis conformations likely are identical for all the carotenoi ... | 1978 | 99169 |
| the mechanism of reduction of the ubiquinone pool in photosynthetic bacteria at different redox potentials. | (1) a flash number dependency of flash-induced absorbance changes was observed with whole cells of rhodospirillum rubrum and chromatophores of r. rubrum and rhodopseudomonas sphaeroides wild type and the g1c mutant. the oscillatory behavior was dependent on the redox potential; it was observed under oxidizing conditions only. absorbance difference spectra measured after each flash in the 275--500 nm wavelength region showed that a molecule of ubiquinone, r, is reduced to the semiquinone (r-) aft ... | 1978 | 99172 |
| oxonol dyes as monitors of membrane potential. their behavior in photosynthetic bacteria. | the reponses of oxonol dyes to single and multiple single turnovers of the photosynthetic apparatus of photosynthetic bacteria have been studied, and compared with the responses of the endogenous carotenoid pigments. the absorbance changes of the oxonols can be conveniently measured at 587 nm, because this is an isosbestic point in the 'light-minus-dark' difference spectrum of the chromatophores. the oxonols appear to respond to the light-induced 'energization' by shifting their absorption maxim ... | 1979 | 103582 |
| activation of ala synthetase by reduced thioredoxin in rhodopseudomonas spheroides y. | | 1979 | 109312 |
| [spectral position of the principal absorption band of pigment complex p870 and the kinetics of photo-induced oxidoreductions in the reaction centers and chromatophores of purple bacteria with preparations at different temperatures and having different degrees of hydration]. | in isolated photosynthetic reaction centres of rps. spheroides and chromatophores r. rubrum the spectral position of the longest wavelength absorption band of p870, effectiveness of electron removal from the photochemical pair (p870 -- primary electron acceptor, a1) and the rate constant for recombination of photooxidized p870 with photoreduced a1 undergo marked and fully reversible changes over the temperature interval from +20 to -70 degrees. dehydration of the samples has the effect similar t ... | 1977 | 109746 |
| [possible role of macromolecular components in the functioning of photosynthetic reaction centers of purple bacteria]. | the temperature dependencies of the photoconversion of pigments p870--p890 were studied using isolated chromatophores and photosynthetic reaction centres (rc's) of purple bacteria. the samples were prepared by extraction with organic solvents (light petroleum and a combination of light petroleum and methanol) and modified through cross-linking the functional groups of proteins by treatment with glutaraldehyde or denatured by various physical and chemical treatments. the data provide further evid ... | 1977 | 109747 |
| the preparation and characterization of different types of light-harvesting pigment-protein complexes from some purple bacteria. | a general strategy, with some specific examples, is given for the isolation and purification of detergent-soluble, antenna pigment-protein complexes from the photosynthetic membranes. absorption, fluorescence and circular dichroism spectra, and the pigment and protein composition of b800-b850-protein and b890-protein complexes of some purple bacteria (rhodospirillum rubrum, rhodopseudomonas sphaeroides and rps. capsulata and chromatium vinosum) are discussed. we conclude that there are probably ... | 1978 | 110568 |
| [use of urea by purple bacteria]. | strains of purple sulfur bacteria (chromatium minutissimum, ectothiorhodospira shaposhnikovii, thiocapsa roseopersicina, lamprobacter modestohalophilus) and nonsulfur bacteria (rhodopseudomonas palustris, rh. spheroides, rhodospirillum rubrum) grow in media containing urea as a source of nitrogen at concentrations from 0.5 to 5.0%. they can also utilize the carbon of urea and thus grow in the absence of bicarbonate. urea is decomposed by all the studied purple bacteria with the participation of ... | 1979 | 112359 |
| photoreaction center of photosynthetic bacteria. 2. size and quaternary structure of the photoreaction centers from rhodospirillum rubrum strain g9 and from rhodopseudomonas sphaeroides strain 2.4.1. | the photoreaction center from rhodospirillum rubrum strain g9 binds about 6 times as much sodium dodecyl sulfate as certain proteins commonly used as molecular weight markers for sodium dodecyl sulfate--polyacrylamide gel electrophoresis. this presumably explains the apparent discrepancy between the molecular weight of the photoreaction center determined by electrophoresis (76 000) and its minimal molecular weight (87 000). the molecular weight of the photoreaction center solubilized with triton ... | 1979 | 114213 |
| changes in the acyl lipid composition of photosynthetic bacteria grown under photosynthetic and non-photosynthetic conditions. | the acyl lipids and their constituent fatty acids were studied in the photosynthetic bacteria rhodospirillum rubrum, rhodopseudomonas capsulata and rhodopseudomonas sphaeroides, which were grown under photosynthetic and non-photosynthetic conditions. the major lipids were found to be phosphatidylethanolamine, phosphatidylglycerol and cardiolipin in each bacterium. the two rhodopseudomonas species also contained significant quantities of phosphatidylcholine. other acyl lipids accounted for less t ... | 1979 | 115463 |
| two regimens of electrogenic cyclic redox chain operation in chromatophores of non-sulfur purple bacteria. a study using antimycin a. | antimycin a causes a biphasic suppression of the light-induced membrane potential generation in rhodospirillum rubrum and rhodopseudomonas sphaeroides chromatophores incubated anerobically. the first phase is observed at low antibiotic concentrations and is apparently due to its action as a cyclic electron transfer inhibitor. the second phase is manifested at concentrations which are greater than 1--2 mum and is due to uncoupling that may be connected with an antibiotic-induced dissipation of th ... | 1979 | 116681 |
| [genetic bases for the selection of microorganisms using analogs]. | the main mechanisms are considered for biosynthesis processes regulation by means of repression and inhibition with final products. on the basis of these mechanisms the state and prospects of the directed alteration of various stages in regulating the synthesis of primary and secondary metabolites, using breeding selection of mutants resistant to analogues are discussed. the main regularities are presented for using analogues of primary metabolites in the breeding strains with overproduction of ... | 1975 | 128859 |
| physical parameters and possible regulation of zeta-aminolevulinic acid synthetase. | physical measurements were made on the zeta-aminolevulinic acid synthetase from rhodopseudomonas spheroides. these include a stokes radius of 3.8 nm, determined by gel filtration, and sedimentation coefficient of 5.46 s by sucrose density gradient centrifugation. from these measurements and the value of partial specific volume of 0.732 ml/g determined from the amino acid composition, the following physical constants were calculated: molecular weight, 88000; diffusion coefficient, 5.65 x 10(-7) c ... | 1978 | 153666 |
| different molecular forms of d-ribulose-1,5-bisphosphate carboxylase from rhodopseudomonas sphaeroides. | ribulose-1,5-bisphosphate (rbu-p2) carboxylase isolated from rhodopseudomonas sphaeroides 2.4.1.ga was separated into two different forms by deae-cellulose column chromatography. both forms, designated peak i and peak ii have been purified to homogeneity by the criterion of polyacrylamide disc-gel electrophoresis. the peak i carboxylase has a molecular weight of 550,000, while the peak ii carboxylase is a smaller protein having a molecular weight of approximately 360,000. sodium dodecyl sulfate ... | 1977 | 14141 |
| lysine as the substrate binding site of porphobilinogen synthase of rhodopseudomonas spheroides. | the 14c labelled inactive protein obtained by sodium borohydride reduction of the enzyme, porphobilinogen synthase of rhodopseudomonas spheroides, in the presence of [4-14c]5-aminolevulinic acid, gave on acid hydrolysis and subsequent electrophoresis or two-dimensional chromatography a major radioactive spot which was confirmed to be n-epsilon-[4-(-5aminovaleric acid)]lysine (ala-lysine) by comparing its co-chromatographic and electrophoretic behaviour with the chemically synthesized ala-lysine. ... | 1978 | 153667 |
| mode of binding of pyridoxal phosphate to 5-aminolevulinate synthase. | 5-aminolevulinate synthase of rhodopseudomonas spheroides interacts with its cofactor, pyridoxal phosphate, and shows an absorption maximum at 430 nm with a probable shoulder at 320--330 nm. the enzyme-plp complex absorbing at 430 nm is the predominant species at ph 7.2 and can be reduced by nabh4 at neutral ph with a spectral shift of the absorption maximum to 325 nm. these data suggests the formation of a schiff base rather than a substituted aldimine between the enzyme and pyridoxal phosphate ... | 1978 | 154217 |
| orientation of chromatophores and spheroplast-derived membrane vesicles of rhodopseudomonas sphaeroides: analysis by localization of enzyme activities. | | 1979 | 157720 |
| immunochemical analysis of membrane vesicles and chromatophoresis of rhodopseudomonas sphaeroides by crossed immunoelectrophoresis. | | 1979 | 159833 |
| asymmetry of an energy transducing membrane the location of cytochrome c2 in rhodopseudomonas spheroides and rhodopseudomonas capsulata. | monospecific antibodies have been prepared against cytochrome c2 from rhodopseudomonas spheroides and rhodopseudomonas capsulata, and against cytochrome c' from rps. capsulata. these antibodies precipitated their respective antigens, but did not cross react with a wide range of procaryotic or eucaryotic cytochromes, or with other bacterial proteins. the cytochromes produced during aerobic growth were immunologically indistinguishable from those produced during photosynthetic growth. cytochrom ... | 1975 | 164941 |
| endor experiments on chlorophyll and bacteriochlorophyll in vitro and in the photosynthetic unit. | | 1975 | 166591 |
| the regulation of heme and chlorophyll synthesis in bacteria. | | 1975 | 166593 |
| a kinetic completion of the cyclic photosynthetic electron pathway of rhodopseudomonas sphaeroides: cytochrome b-cytochrome c2 oxidation-reduction. | in rhodopseudomonas sphaeroides, following a single-turnover flash of light, cytochrome c2 is oxidized by reaction center bacteriochlorophyll, and a cytochrome b is reduced by the primary electron acceptor, probably via ubiquinone. in this report we show that, in the uncoupled state, the rate of re-oxidation of the cytochrome b is identical to the rate of reduction of the cytochrome c2, a kinetic completion of the cyclic photosynthetic electron transport system. | 1975 | 166671 |
| some experiments on the primary electron acceptor in reaction centres from rhodopseudomonas sphaeroides. | the bacterial reaction center absorbance change at 450 nm (a-450) assigned to an anionic semiquinone, has been suggested as a candidate for the reduced form of the primary electron acceptor in bacterial photosynthesis. in reaction centers of rhodopseudomonas sphaeroides we have found kinetic discrepancies between the decay of a-450 and the recovery of photochemical competence. in addition, no proton uptake is measurable on the first turnover, although subsequent ones elicit one proton bound per ... | 1975 | 168920 |
| [primary processes in energy transfer of photosynthesis (author's transl)]. | | 1975 | 169548 |
| characterization of two soluble ferredoxins as distinct from bound iron-sulfur proteins in the photosynthetic bacterium rhodospirillum rubrum. | in an earlier investigation (shanmugam, k. t., buchanan, b. b., and arnon, d. i. (1972) biochim. biophys. acta 256, 477-486) the extraction of ferredoxin from rhodospirillum rubrum cells with the aid of a detergent (triton x-100) and acetone revealed the existence of two types of ferredoxin (i and ii) and led to the conclusion that both are membrane-bound. in the present investigation, ferredoxin and acid-labile sulfur analyses of photosynthetic membranes (chromatophores) and soluble protein ext ... | 1975 | 172494 |
| photochemical activities of reaction centers from rhodopseudomonas sphaeroides at low temperature and in the presence of chaotropic agents. | light-induced absorbance changes were measured at low temperatures in reaction center preparations from rhodopseudomonas sphaeroides. absorbance difference spectra measured at 100 degrees k show that ubiquinone is photoreduced at this temperature, both by continuous light and by a short actinic flash. the reduction occurred with relatively high efficiency. these results give support to the idea that ubiquinone is involved in the primary photochemical reaction in rhodopseudomonas sphaeroides. red ... | 1976 | 174746 |
| investigation of the structure of the reaction center in photosynthetic bacteria by optical detection of triplet state magnetic resonance. | | 1976 | 183778 |
| kinetics of populating and depopulating of the components of the photoinduced triplet state of the photosynthetic bacteria rhodospirillum rubrum, rhodopseudomonas spheroides (wild type), and its mutant r-26 as measured by esr in zero-field. | optically detected esr spectra in zero magnetic field of the triplet state of three photosynthetic bacteria are presented. the zero field splitting parameters [d] and [e] and the widths of the resonances show small but significant differences for the three bacteria. the resonance lines are inhomogeneously broadened as demonstrated by hole-burning experiments. the populating probabilities and depopulating rates for the triplet sublevels have been measured. the populating kinetics are very similar ... | 1976 | 183816 |
| time-resolved esr and chemically induced dynamic electron polarisation of the primary reaction in a reaction center particle of rhodopseudomonas sphaeroides wild type at low temperature. | | 1977 | 190035 |
| electron acceptors of photosynthetic bacterial reaction centers. direct observation of oscillatory behaviour suggesting two closely equivalent ubiquinones. | when reaction centers are illuminated by a series of single turnover flashes ubisemiquinone is formed and destroyed on alternate flashes. this oscillatory behaviour can be observed with both optical and electron spin resonance techniques. the oscillations are dependent upon the presence of excess ubiquinone in a manner which suggests that two molecules may act almost equivalently as metastable primary acceptors forming a two-electron gate between the one-electron primary photoact and a two-elect ... | 1977 | 191074 |
| the influence of transmembrane potentials of the redox equilibrium between cytochrome c2 and the reaction center in rhodopseudomonas sphaeroides chromatophores. | | 1977 | 196931 |
| synthesis of photopigments and electron transport components in synchronous phototrophic cultures of rhodopseudomonas sphaeroides. | the kinetics of synthesis and incorporation of the photosynthetic pigments and several of the major oxidative and photosynthetic electron transport components of rhodopseudomonas sphaeroides have been studied during synchronous and asynchronous phototrophic growth. the photosynthetic pigments and cytochromes c and b, measured spectroscopically, exhibited continuous patterns of synthesis and incorporation into the membrane particulate fraction in both synchronous and asynchronous cultures. succin ... | 1978 | 201634 |
| single and multiple turnover reactions in the ubiquinone-cytochrome b-c2 oxidoreductase of rhodopseudomonas sphaeroids: the physical chemistry of the major electron donor to cytochrome c2, and its coupled reactions. | we have examined the thermodynamic properties of the physiological electron donor to ferricytochrome c2 in chromatophores from the photosynthetic bacterium rhodopseudomonas sphaeroides. this donor (z), which is capable of reducing the ferricytochrome with a halftime of 1-2 ms under optimal conditions, has an oxidation-reduction midpoint potential of close to 150 mv at ph 7.0, and apparently requires two electrons and two protons for its equilibrium reduction. the state of reduction of z, which m ... | 1977 | 202311 |
| determination of the decay rates of the triplet state of rhodopseudomonas sphaeroides by fast laser-flash esr spectroscopy. | | 1978 | 202494 |
| facile assay of enzymes unique to the calvin cycle in intact cells, with special reference to ribulose 1,5-bisphosphate carboxylase. | | 1978 | 204219 |
| electron spin polarization in photosynthesis and the mechanism of electron transfer in photosystem i. experimental observations. | transient electron paramagnetic resonance (epr) methods are used to examine the spin populations of the light-induced radicals produced in spinach chloroplasts, photosystem i particles, and chlorella pyrenoidosa. we observe both emission and enhanced absorption within the hyperfine structure of the epr spectrum of p700+, the photooxidized reaction-center chlorophyll radical (signal i). by using flow gradients or magnetic fields to orient the chloroplasts in the zeeman field, we are able to influ ... | 1978 | 204369 |
| second order kinetics of the reduction of cytochrome c2 by the ubiquinone cytochrome b-c2 oxidoreductase of rhodopseudomonas sphaeroides. | | 1978 | 207691 |
| electron spin resonance in zero magnetic field of the reaction center triplet of photosynthetic bacteria. | the decay rates kx, ky, kz of the individual spin levels of the light-induced triplet state have been accurately measured by the zero-field resonance technique under conditions of very low light intensity and a microwave sweep rate of 2.5 mhz/microseconds, which is in excess of that commonly used in optical detection magnetic resonance experiments. the rates ku found correspond well with those previously determined under somewhat different conditions (hoff, a.j. (1976) biochim. biophys. acta 440 ... | 1978 | 208604 |
| properties of a cytochrome c-enriched light particulate fraction isolated from the photosynthetic bacterium rhodopseudomonas spheroides. | differential centrifugation of suspensions of french-press-disrupted rhodopseudomonas spheroides yielded a light particulate fraction that was different in many properties from the bulk membrane fraction. it was enriched in cytochrome c and had a low cytochrome b content. when prepared from photosynthetically grown cells this fraction had a very low specific bacteriochlorophyll content. the cytochrome c of the light particles differed in absorption maxima at 77k from cytochrome c2 attached to me ... | 1978 | 212023 |
| lipid-protein associations in chromatophores from the photosynthetic bacterium rhodopseudomonas sphaeroides. | lipid-protein interactions were examined in chromatophores isolated from the photosynthetic bacterium rhodopseudomonas sphaeroides using lipid spin-labels. the chromatophores contain fluid bilayer and a significant amount of lipid immobilized by membrane proteins. for a typical preparation of cells grown under 600 ft-c illumination, 59% of the spin-labeled fatty acids were bound. essentially the entire length of the 18-carbon fatty acid chain was immobilized, judging from results obtained with t ... | 1978 | 212104 |
| [picosecond fluorometry of rhodopseudomonas sphaeroides strain 1760-1 bacteria]. | | 1978 | 212114 |
| diffusion-potential-induced oxidation and reduction of cytochromes in chromatophores from rhodopseudomonas sphaeroides. | a membrane potential jump was induced by the addition of valinomycin in the presence of a kcl concentration gradient across the membrane of rhodopseudomonas sphaeroides chromatophores. as well as a carotenoid band shift, which is known to be an indicator of membrane potential, absorbance changes due to the oxidation-reduction reactions of cytochromes accompanied the jump. under aerobic conditions with no reductant added, a part of cytochrome c2 was reduced by an inside-positive potential jump of ... | 1978 | 214426 |
| electrogenic events in the ubiquinone-cytochrome b/c2 oxidoreductase of rhodopseudomonas sphaeroides. | the reductant of ferricytochrome c2 in rhodopseudomonas sphaeroides is a component, z, which has an equilibrium oxidation-reduction reaction involving two electrons and two protons with a midpoint potential of 155 mv at ph 7. under energy coupled conditions, the reduction of ferricytochrome c2 by zh2 is obligatorily coupled to an apparently electrogenic reaction which is monitored by a red shift of the endogeneous carotenoids. both ferricytochrome c2 reduction and the associated carotenoid bands ... | 1979 | 216398 |
| the kinetics of flash-induced electron flow in bacteriochlorophyll-less membranes of rhodopseudomonas sphaeroides reconstituted with reaction centres. | | 1979 | 216400 |
| azethoxyl nitroxide spin labels. esr studies involving thiourea crystals, model membrane systems and chromatophores, and chemical reduction with ascorbate and dithiothreitol. | trans- and cis-azethoxyl nitroxides 1, 2, 3 and 4 can be trapped in the cavities of thiourea crystals. the presence of a single gauche conformation on either side of the pyrrolidine ring within the crystals was indicated by the esr spectra. rotation about the long molecular axis then corresponds approximately to y-axis motion of the nitroxide moiety. proxyl nitroxides in which the nitroxide group is located on the penultimate carbon of long chain lipids can also be trapped and were shown to adop ... | 1979 | 217428 |
| [conformational mobility and functional activity of photosynthetic reaction centers of rhodopseudomonas sphaeroides]. | in pigment-protein complexes of photosynthetic reaction centres (rc's), extracted from chromatophore membranes of rps. sphaeroides with sodium dodecylsulphate, functional activity and intramolecular mobility were studied as a function of temperature and hydration by use of the technique of optical absorbance and esr spectroscopy. over the studied temperature range from +20 to -120 degrees c and at a relative humidity (p/ps) from 0.9 to 0.1, there observed a close interrelationship between revers ... | 1979 | 220525 |
| ubiquinone in rhodopseudomonas sphaeroides. some thermodynamic properties. | in rhodopseudomonas sphaeroides chromatophores there are 25 +/- 3 ubiquinone (q) molecules/reaction center protein. they comprise several thermodynamically and functionally different ubiquinone complements. there are approx. 19 ubiquinones (em7 = 90 mv) in the main ubiquinone complement which, within experimental resolution, appears thermodynamically homogenous and follows the redox reaction q + 2e + 2h+ in equilibrium with qh2 from ph 5--9. a method which takes advantage of the 2h+ bound/molecu ... | 1979 | 221012 |
| cytochrome c2--reaction centre coupling in chromatophores of rhodopseudomonas sphaeroides and rhodopseudomonas capsulata. | | 1979 | 221250 |
| electron transfer in the photosynthetic reaction center. | | 1976 | 222400 |
| chlorophyll radicals and primary events. | | 1976 | 222403 |
| localization of the primary quinone binding site in reaction centers from rhodopseudomonas sphaeroides r-26 by photoaffinity labeling. | | 1979 | 223628 |
| comparison of permeant ion uptake and carotenoid band shift as methods for determining the membrane potential in chromatophores from rhodopseudomonas sphaeroides ga. | 1. a comparison was made of two methods for estimating the membrane potential in chromatophores from rhodopseudomonas sphaeroides ga. illuminated chromatophores generated a potential that is apparently much larger when estimated on the basis of the red-band shift of carotenoids rather than from the extent of uptake of the permeant scn- ion. 2. in contrast, when the chromatophores were oxidizing nadh or succinate the uptake of scn- indicated a larger membrane potential than was estimated from the ... | 1979 | 226068 |
| magnetophotoselection of the triplet state of reaction centers from rhodopseudomonas sphaeroides r-26. | reaction centers of the photosynthetic bacterium rhodopseudomonas sphaeroides r-26, give rise to large triplet state epr signals upon illumination at low temperature (11 k). utilizing monochromatic polarized light to generate the epr spectra (magnetophotoselection) we have shown that the intensities of the observed triplet signals are strongly dependent upon the wavelength and polarization direction of the excitation. these data can be used to calculate the orientations of the excited transition ... | 1979 | 226130 |
| microsecond photooxidation kinetics of cytochrome c2 from rhodopseudomonas sphaeroides: in vivo and solution studies. | | 1979 | 226405 |
| [electron acceptors in photosynthetic reaction centers from rhodopseudomonas spheroides]. | using optical differential spectroscopy and epr, a parallel study of light-induced electron transfer between the primary (x1) and secondary (x2) quinone-like acceptors in the preparations of reaction centers (rc) isolated from bacterial chromatophore membranes with sodium dodecyl sulfate was carried out. the data from direct measurements of the rate constant temperature dependence for the interaction between light-reduced x1 and x2 (kx1x2) are in good agreement with the data calculated from the ... | 1979 | 227482 |
| the recognition of a special ubiquinone functionally central in the ubiquinone-cytochrome b-c2 oxidoreductase. | although the energy conserving membranes of the photosynthetic bacterium rhodopseudomonas sphaeroides contain a 25 (+/- 3)-fold molar excess of ubiquinone over the photochemical reaction center, the activity of the ubiquinone-cytochrome b-c2 oxidoreductase is unaffected by quinone extraction until only 3, or at most 4, ubiquinones remain; only then does further extraction prevent the function of the oxidoreductase. since 2 of these last ubiquinones are integral parts of the photochemical reactio ... | 1979 | 227864 |
| [possible pathways for acetyl-coa formation by purple bacteria]. | purple sulfur (ectothiorhodospira shaposhnikovii, chromatium minutissimum, lamprobacter modestohalophilus, thiocapsa roseopersicina) and nonsulfur (rhodospirillum rubrum, rhodopseudomonas palustris, rhodopseudomonas spheroides) bacteria are capable of forming acetyl-coa synthetase, phosphotransacetylase and acetokinase independent of the medium composition and growth conditions. in all of the purple sulfur bacteria with an exception of e. shaposhnikovii, the activity of acetokinase is much highe ... | 1979 | 228168 |
| microbial oxidation of protoporhydrinogen, an intermediate in heme and chlorphyll biosynthesis. | | 1979 | 228599 |
| transfer of light-induced electron-spin polarization from the intermediary acceptor to the prereduced primary acceptor in the reaction center of photosynthetic bacteria. | in reaction centers and chromatophores of photosynthetic bacteria strong light-induced emissive esr signals have been found, not only after a flash but also under continuous illumination. the signal, with g = 2.0048 and delta hpp = 7.6 g, is only present under reducing conditions in material in which the primary acceptor, ubiquinone, u and its associated high-spin ferrous ion are magnetically uncoupled. its amplitude under continuous illumination is strongly dependent on light intensity and on m ... | 1979 | 228714 |
| the primary photochemical reaction to bacterial photosynthesis. | | 1975 | 235329 |
| the rieske iron-sulfur center in mitochondrial and photosynthetic systems: em/ph relationships. | | 1975 | 235450 |
| characterization of the phototrap in photosynthetic bacteria. | | 1975 | 237454 |
| cytochrome c2 and reaction center of rhodospeudomonas spheroides ga. membranes. extinction coefficients, content, half-reduction potentials, kinetics and electric field alterations. | the reduced minus oxidized extinction coefficients (delta epsilon-red-ox) of reaction center p605 when in the chromatophore is about 20% smaller than in the detergent-isolated state. presumably the coupling of the reaction center protein to the antenna bacteriochlorophylls and carotenoids causes this hypochromism. the chromatophore values for p605 are 19.5 mm- minus 1 times cm- minus 1 with the spectrophotometer on single beam mode at 605 nm, and 29.8 mm- minus 1 times cm- minus 1 on dual wavele ... | 1975 | 237543 |
| the mechanism of the bond forming events in pyridine nucleotide linked oxidoreductases. studies with epoxide inhibitors of lactic dehydrogenase and beta-hydroxybutyrate dehydrogenase. | 2,3-epoxybutyrate and 2,3-epoxypropionate act as effective competitive inhibitors of pig heart lactic dehydrogenase. kiapp for both inhibitors was ph dependent and varied according to the general equation kiapp = ki(1 +ka/h+) which may be predicted if the binding of the epoxide to the e-nadh complex involves a compulsory protonation step. values of ki(epoxybutyrate), ki(epoxypropionate) and pka were estimated as 150 mum, 860 mum, and 6.8, respectively. the formation of an e-nadh epoxide inhibito ... | 1975 | 238558 |
| electrical potential changes, h+ translocation and phosphorylation induced by short flash excitation in rhodopseudomonas sphaeroides chromatophores. | 1. the basal decay of the carotenoid shift of chromatophores from photosynthetic bacteria following short flash excitation is approximately biphasic. the decay indicates the dissipation of the transmembrane electrical potential. 2. the h+ efflux following rapid h+ binding after a flash, measured from the colour change of added cresol red, shows very similar kinetics to the carotenoid shift decay suggesting that the dissipation of the electric potential decay is a consequence of the h+ efflux. 3. ... | 1975 | 240444 |
| the extent of the stimulated electrical potential decay under phosphorylating conditions and the h+/atp ratio in rhodopseudomonas sphaeroides chromatophores following short flash excitation. | 1. in chromatophores from rps. sphaeroides, the stimulation by adp and pi of the electric potential decay indicated by the carotenoid shift is greater than the stimulation of the decay of ph change indicated by the colour change of added cresol red under similar conditions. this difference is attributed to h+ consumption during the synthesis of atp. the ratio of h+ translocated across the membrane to atp synthesized was estimated to be approximately 1.7 h+/atp. 2. the stimulation of the electric ... | 1975 | 240445 |
| thermodynamic resolution of the iron-sulfur centers of the succinic dehydrogenase of rhodopseudomonas sphaeroides. | | 1977 | 300000 |
| naturally occurring viral r plasmid with a circular supercoiled genome in the extracellular state. | | 1977 | 300145 |
| sidedness of membrane structures in rhodopseudomonas sphaeroides. electrochemical titration of the spectrum changes of carotenoid in spheroplasts, spheroplast membrane vesicles and chromatophores. | the shift of the carotenoid absorption spectrum induced by illumination and valinomycin-k+ addition was investigated in membrane structures with different characteristics and opposite sidednesses isolated from rhodopseudomonas sphaeroides. right-side-out membrane structures were prepared by isotonic lysozyme-edta treatment of the cells (spheroplasts) and by hypotonic treatment of spheroplasts (spheroplast membrane vesicles). inside-out membrane structures ("chromatophores") were obtained by trea ... | 1977 | 300247 |
| the carotenoid shift in rhodopseudomonas sphaeroides. the flash induced change. | a mutant, rhodopseudomonas sphaeroides gic, having only one major carotenoid, neurosporene, is described. the spectrum of the carotenoid shift in this mutant is analysed and it is concluded that only 7-11% of the pigment is involved under conditions of steady-state illumination and that this pigment undergoes a shift of 7 nm. the spectrum of the carotenoid shift under conditions of multi-flash illumination is examined for changes in shape concordant with a progressive red shift of the pigment wi ... | 1977 | 300248 |
| reconstituted energy transfer from antenna pigment-protein to reaction centres isolated from rhodopseudomonas sphaeroides. | efficient energy transfer has been reconstituted between an antenna pigment-protein and reaction centres isolated from the photosynthetic membrane of rhodopseudomonas sphaeroides. the reconstituted system has fluorescence induction kinetics and fluorescence yields similar to those obtained from antenna bacteriochlorophyll in chromatophores. the results indicated that closed reaction centres quench fluorescence from the antenna pigment-protein, although not as strongly as photochemically active r ... | 1977 | 300249 |
| secondary electron transfer in reaction centers of rhodopseudomonas sphaeroides. out-of-phase periodicity of two for the formation of ubisemiquinone and fully reduced ubiquinone. | electron transfer between purified reaction centers from rhodopseudomonas sphaeroides and exogenous ubiquinone has been studied in the presence of electron donors by measurements of light-induced absorbance changes following a sequence of short actinic light flashes. each odd flash promotes the formation of a molecule of ubisemiquinone; after each even flash the semiquinone disappears and a molecule of the fully reduced quinone appears. we interpret these results by means of a model where a spec ... | 1977 | 300250 |
| quaternary structure of delta-aminolevulinic acid synthase from rhodopseudomonas spheroides. | delta-aminolevulinic acid synthase (succinyl-coa: glycine c-succinyltransferase (decarboxylating) ec 2.3.1.37) was purified from rhodopseudomonas spheroides. the purity of the enzyme preparation was established by its behavior in disc electrophoresis in the presence and absence of sodium dodecyl sulfate and by analytical ultracentrifugation. the molecular weight of the enzyme as determined by sedimentation equilibrium was found to be about 80,300, a value similar to those obtained by gel filtrat ... | 1977 | 300378 |
| further evidence for dissipative energy migration via triplet states in photosynthesis. the protective mechanism of carotenoids in rhodopseudomonas spheroides chromatophores. | the protection action of carotenoids against irreversible photodestruction was discovered in photosynthetic bacteria by stanieda and coworkers. in green plant material it was found by wolff and witt (1969) z. naturforsch, 24b, 1031-1037 and (1972) proc. 2nd. int. congr. photosynthesis res. stresa (forti, g., avron, m. and melandri, a., eds.), vol. 2, pp. 931-936, dr. w. junk, n. v. publ. the hague) that the formation of special carotenoid triplet states (via very rapid energy transfer from excit ... | 1977 | 300630 |