[69] Photochemical reaction centers from Rhodopseudomonas spheroides

Clayton, Roderick K.; Wang, Richard T.

doi:10.1016/s0076-6879(71)23145-1

Cited by 184 publications

(63 citation statements)

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“…A detailed understanding of these Bchlprotein complexes requires their isolation from the membrane. After detergent treatment, reaction center preparations have been purified from chromatophores of both the carotenoidless mutant R-26 (8,9) and the wild type (10); similarly, the B850 complex has also been isolated from the latter (11). To our knowledge, no reports on the isolation of B875 from wild-type R. sphaeroides have appeared.…”

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confidence: 99%

Isolation and characterization of the pigment-protein complexes of Rhodopseudomonas sphaeroides by lithium dodecyl sulfate/polyacrylamide gel electrophoresis.

Broglie¹,

Hunter²,

Delepelaire³

et al. 1980

Proc. Natl. Acad. Sci. U.S.A.

154

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When purified photosynthetic membranes from Rhodopseudomonas sphaeroides were treated with lithium dodecyl sulfate and subjected to polyacrylamide gel electrophoresis at 4VC, up to 11 pigment-protein complexes were resolved. Absorption spectra revealed that the smallest complex contained reaction center pigments and the others contained the antenna components B850 and B875 in various proportions. Of these antenna complexes, the largest was almost entirely B850 and the smallest contained only B875. After solubilization at 1000C and electrophoresis on polyacrylamide gradient gels, the B850 complex gave rise to two polypeptide components migrating with apparent M, of 10,000 and 8000, whereas with the B875 complex, two components were observed with apparent Mr of 12,000 and 8000. The reaction center complex gave rise to only the 24 The photosynthetic apparatus of the photoheterotrophic bacterium Rhodopseudomonas sphaeroides is localized in a system of intracytoplasmic membranes (1) which, upon mechanical disruption, gives rise to vesicles termed "chromatophores" (2). These contain most of the antenna (light-harvesting) and reaction center bacteriochlorophyll a (Bchl)-protein complexes (2). Radiant energy harvested by antenna migrates to the reaction center where productive photochemistry occurs (3, 4). Absorption spectra reveal two antenna complexes designated B850 and B875 on the basis of their absorption maxima in the near-infrared (5). B875 is associated with the reaction center in a molar ratio of about 30:1 (6), unlike B850 levels which vary with changes in light intensity (6) or the stage of membrane development (7). A detailed understanding of these Bchlprotein complexes requires their isolation from the membrane. After detergent treatment, reaction center preparations have been purified from chromatophores of both the carotenoidless mutant R-26 (8, 9) and the wild type (10); similarly, the B850 complex has also been isolated from the latter (11). To our knowledge, no reports on the isolation of B875 from wild-type R. sphaeroides have appeared.Recently, a novel procedure has been developed for the isolation of chlorophyll-protein complexes from thylakoid membranes of Chlamydomonas reinhardtii and higher plants (12). After solubilization of membranes in lithium dodecyl sulfate (LiDodSO4) and polyacrylamide gel electrophoresis with this detergent at 40C, two new chlorophyll-protein complexes were isolated. Under these conditions, the dissociation of pigment from the complexes is minimized. LiDodSO4 was used because the sodium salt, previously used, precipitates in the cold. It is shown here that, in R. sphaeroides wild-type chromatophores, LiDodSO4/polyacrylamide gel electrophoresis provides a convenient procedure for the isolation of the B875-antenna complex in addition to B850 and reaction centers that lack the heavy subunit.MATERIALS AND METHODS R. sphaeroides (NCIB 8253) was grown phototrophically at 30°C essentially as described (13) with 40-W General Electric incandescent lamps at a light intensi...

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confidence: 99%

Isolation and characterization of the pigment-protein complexes of Rhodopseudomonas sphaeroides by lithium dodecyl sulfate/polyacrylamide gel electrophoresis.

Broglie¹,

Hunter²,

Delepelaire³

et al. 1980

Proc. Natl. Acad. Sci. U.S.A.

154

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“…spheroides [6,7] and R. rubrum [8] in that the reaction centre complex is substantially free of secondary electron carriers other than quinones. There are, however, several changes in the positions of the spectral peaks, making the reaction centres described here green compared with the 'ice-blue' of those fromRps.…”

Section: Methods and Resultsmentioning

confidence: 99%

“…This has been achieved [6][7][8] using the zwitterionic detergent LDAO (lauryl dimethyl amine oxide) on blue green (carotenoid less) mutants of Rps. spheroides [6,7] and R. rubrum [8]. However, to date, no reaction centre preparations have been prepared from Rps.…”

Section: Introductionmentioning

confidence: 99%

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Photochemical reaction centres from Rhodopseudomonas capsulata Ala pho⁺

Prince

Crofts

1973

FEBS Letters

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“…Current research on the mechanism of the initial steps in photosynthesis focuses on three problems: (i) the identity and stoichiometry of obligatory components, (ii) the time sequence of energy and electron transfers and the identity of molecular constituents participating in these transfers, and (iii) the spacial relationships among the principle components (relative orientations and distances). For the most widely studied case of the purple photosynthetic bacterium Rhodopseudomonas spheroides (R-26 mutant), a great deal of progress has been made in each of these areas as a consequence of the isolation of highly purified, low molecular weight, functional reaction centers (1). These reaction centers contain three small proteins, four bacteriochlorophylls a (BChls), and two bacteriopheophytins a (BPheos, BChl in which 2 H replace Mg) (2).…”

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Chromophore organization in photosynthetic reaction centers: High-resolution magnetophotoselection

Boxer

Roelofs

1979

Proc. Natl. Acad. Sci. U.S.A.

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The electron spin resonance spectrum of the triplet excited state of Rhodopseudomonas spheroides R-26 reaction centers has been studied after excitation with the polarized narrow-bandwidth output of a tunable dye laser from 520 to 670 nm. A theory is developed relating experimental observables to the angles between the electronic transition dipole moment of the excited chromophore and the principle magnetic axis system of the triplet state of the dimeric trap. Data is presented which demonstrates that the treatment is correct and useful and angles are obtained for the Q. transitions of bacteriopieophytin. High-resolution magnetophotoselection data in the region of the bacteriochlorophyll Qx transitions can be combined with polarized photobleaching experiments to provide direct information on the structure of dimeric trap. Current research on the mechanism of the initial steps in photosynthesis focuses on three problems: (i) the identity and stoichiometry of obligatory components, (ii) the time sequence of energy and electron transfers and the identity of molecular constituents participating in these transfers, and (iii) the spacial relationships among the principle components (relative orientations and distances). For the most widely studied case of the purple photosynthetic bacterium Rhodopseudomonas spheroides (R-26 mutant), a great deal of progress has been made in each of these areas as a consequence of the isolation of highly purified, low molecular weight, functional reaction centers (1). These reaction centers contain three small proteins, four bacteriochlorophylls a (BChls), and two bacteriopheophytins a (BPheos, BChl in which 2 H replace Mg) (2). The electronic states of two BChls interact to produce a low-energy trap [(BChl)2 or P870] (3, 4) which, on direct excitation or energy transfer from any other chromophore (5), transfers an electron very rapidly (<6 ps) to a BPheo (6-9). If secondary electron transfer is blocked by prior reduction, the radical ion pair [(BChl)2+-BPheo--] lives for several nanoseconds before annihilation to neutrals. This process may generate neutrals either in the singlet ground state or the lowest triplet state of (BChl)2 (10). At low temperature the latter pathway predominates (11) and a spin-polarized electron spin resonance (ESR) spectrum characteristic of the Ams = +I transitions of a triplet species is readily detected and has been discussed (12)(13)(14).Much less is known about reaction center structure. Very recently a number of investigators, notably Clayton et al. (15), , Vermeglio et al. (19), and Shuvalov and Asadov (20), have reported photoselection and linear and circular dichroism measurements on reaction centers, in many cases oriented in stretched films. An analysis of the data provides a detailed picture of the angles among the transition dipole moment axes of each of the reaction center chromophores. At the same time we have adopted an alternate approach which combines high resolution polarized laser excitation and the properties of the triplet ESR s...

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[69] Photochemical reaction centers from Rhodopseudomonas spheroides

Cited by 184 publications

References 5 publications

Isolation and characterization of the pigment-protein complexes of Rhodopseudomonas sphaeroides by lithium dodecyl sulfate/polyacrylamide gel electrophoresis.

Isolation and characterization of the pigment-protein complexes of Rhodopseudomonas sphaeroides by lithium dodecyl sulfate/polyacrylamide gel electrophoresis.

Photochemical reaction centres from Rhodopseudomonas capsulata Ala pho⁺

Chromophore organization in photosynthetic reaction centers: High-resolution magnetophotoselection

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[69] Photochemical reaction centers from Rhodopseudomonas spheroides

Cited by 184 publications

References 5 publications

Isolation and characterization of the pigment-protein complexes of Rhodopseudomonas sphaeroides by lithium dodecyl sulfate/polyacrylamide gel electrophoresis.

Isolation and characterization of the pigment-protein complexes of Rhodopseudomonas sphaeroides by lithium dodecyl sulfate/polyacrylamide gel electrophoresis.

Photochemical reaction centres from Rhodopseudomonas capsulata Ala pho+

Chromophore organization in photosynthetic reaction centers: High-resolution magnetophotoselection

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Photochemical reaction centres from Rhodopseudomonas capsulata Ala pho⁺