Analysis of the optical absorbance spectra of D1-D2-cytochrome b-559 complexes by absorbance-detected magnetic resonance

Vos, R. van der; Leeuwen, Peter Jan van; Braun, Paula; Hoff, A.J.

doi:10.1016/0005-2728(92)90008-p

Cited by 84 publications

(67 citation statements)

References 29 publications

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“…Our ADMR spectrum of the isolated RC is identical to that published by Van der Vos et al [4], much broader than those of BBY and shifted to higher microwave frequencies and to shorter wavelengths with respect to singlet-singlet absorption (not shown). Fig.…”

Section: Fig 1 Shows the Normalized Admr Spectra (Id]-]e] And ]D]+]esupporting

confidence: 85%

“…This task is now more interesting for reaction centers of higher organisms for which direct X-ray structural information is still lacking. Although the similarities between the bacterial and plant reaction centers have been widely discussed, the T-S spectra seem to indicate differences in the interactions between pigments and in the structure of the primary donor [4]. The primary electron donor of PSI1 is associated with a spectral feature of 680 mn and is referred to as P680 [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…In the latter the 3P680 signal is quite narrow while in the isolated centers the corresponding signal is much wider and indicates the presence of heterogeneity clearly produced during the isolation procedures of the complex. The MIA spectrum of P680 was obtained earlier for isolated centers [4] but its analysis is complicated by this heterogeneity. For BBY particles ADMR was performed by den Blanken et al [14] in 1983 but the results are difficult to reconcile with the most recent ones probably due to the prepara-tion and to the scarce knowledge, at that time, concerning the production of the P680 triplet.…”

Section: Introductionmentioning

confidence: 99%

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A well resolved ODMR triplet minus singlet spectrum of P680 from PSII particles

Carbonera

Giacometti

Agostini³

1994

FEBS Letters

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An ADMR T-S spectrum of the primary donor (P680) of photosystem II (PSII) was obtained from anaerobically photoreduced particles. The spectrum is the best resolved obtained so far having a main bleaching band at 684 nm with a lmewidth of only 100 cm-'. The view that this spectrum is produced by native homogeneous P680 unlike those obtained before is defended. A small bleaching observed at 678 nm is discussed in terms of the reaction center structure. One possible interpretation of the observations is that P680 is a very loose dimer with an exciton splitting of only 144 cn-' corresponding to a dimer center-to-center distance of roughly 11.5 A.

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Section: Fig 1 Shows the Normalized Admr Spectra (Id]-]e] And ]D]+]esupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A well resolved ODMR triplet minus singlet spectrum of P680 from PSII particles

Carbonera

Giacometti

Agostini³

1994

FEBS Letters

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“…However, the linear dichroism data that indicate oppositely signed LD features for pheophytins appear to argue against the strict analogy used above (Breton, 1990;van der Vos et al, 1992;van Gorkom & Schelvis, 1993).…”

Section: Pheophytinsmentioning

confidence: 93%

Modeling of the D1/D2 proteins and cofactors of the photosystem II reaction center: Implications for herbicide and bicarbonate binding

1996

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A three-dimensional model of the photosystem I1 (PSII) reaction center from the cyanobacterium Synechocystis sp. PCC 6803 was generated based on homology with the anoxygenic purple bacterial photosynthetic reaction centers of Rhodobacter sphaeroides and Rhodopseudomonas viridis, for which the X-ray crystallographic structures are available. The model was constructed with an alignment of Dl and D2 sequences with the L and M subunits of the bacterial reaction center, respectively, and by using as a scaffold the structurally conserved regions (SCRs) from bacterial templates. The structurally variant regions were built using a novel sequence-specific approach of searching for the best-matched protein segments in the Protein Data Bank with the "basic local alignment search tool" (Altschul SF, Gish W, Miller W, Myers EW, Lipman DJ, 1990, J Mol Biol 215:403-410). and imposing the matching conformational preference on the corresponding D l and D2 regions. The structure thus obtained was refined by energy minimization. The modeled D l and D2 proteins contain five transmembrane a-helices each, with cofactors (4 chlorophylls, 2 pheophytins, 2 plastoquinones, and a non-heme iron) essential for PSII primary photochemistry embedded in them. A p-carotene, considered important for PSII photoprotection, was also included in the model. Four different possible conformations of the primary electron donor P680 chlorophylls were proposed, one based on the homology with the bacterial template and the other three on existing experimental suggestions in literature. The P680 conformation based on homology was preferred because it has the lowest energy.Redox active tyrosine residues important for P680' reduction as well as residues important for PSI1 cofactor binding were analyzed. Residues involved in interprotein interactions in the model were also identified. Herbicide 3-(3,4-dichlorophenyI)-I , 1 -dimethylurea (DCMU) was also modeled in the plastoquinone QB binding niche using the structural information available from a DCMU-binding bacterial reaction center.A bicarbonate anion, known to play a role in PSII, but not in anoxygenic photosynthetic bacteria, was modeled in the non-heme iron site, providing a bidentate ligand to the iron. By modifying the previous hypothesis of Blubaugh and Govindjee (1988, Photosyn Res 1 9 3 -1 2 8 ) , we modeled a second bicarbonate and a water molecule in the Qe site and we proposed a hypothesis to explain the mechanism of QB protonation mediated by bicarbonate and water. The bicarbonate, stabilized by DLR257, donates a proton to Qi-through the intermediate of DLH252; and a water molecule donates another proton to Qi-. Based on the discovery of a "water transport channel" in the bacterial reaction center, an analogous channel for transporting water and bicarbonate is proposed in our PSII model. The putative channel appears to be primarily positively charged near QB and the non-heme iron, in contrast to the polarity distribution in the bacterial water transport channel. The constructed model has ...

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“…From an analysis of spectral characteristics and other features it was concluded that P680 is functionally most likely a Chl monomer and not a dimer as the primary donor P in bacterial RCs [13]. Also, the orientations of the ring plane of P680 and of its Q,-transition moment relative to the membrane seem to be different in PS II compared to bacterial RCs, as concluded from orientation-dependent EPR spectra [14] and from LD-ADMR (LinearDichroic Absorbance Detected Magnetic Resonance) measurements [13], respectively. All these results do not exclude that two Chls are in similar positions as the two bacteriochlorophylls (BChl) of P, but are not excitonitally coupled.…”

Section: Introductionmentioning

confidence: 99%

Similarity of primary radical pair recombination in photosystem II and bacterial reaction centers

et al. 1993

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We report temperature and magnetic field dependent measurements of the recombination dynamics of the radical pair P680+Pheo-in D,D,cytbSSg reaction centers of photosystem II and compare the results to those obtained in bacterial reaction centers. In photosystem II the rate of recombination to the groundstate is found to be slower than in the bacterial reaction centers by a factor of at least 50. This difference arises from the different redox potentials of the pigments of plant and bacterial reaction centers. In contrast, the rate of recombination to the triplet state is similar in all reaction centers, indicating a similar electronic coupling which allows us to conclude upon the structural similarity.

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Analysis of the optical absorbance spectra of D1-D2-cytochrome b-559 complexes by absorbance-detected magnetic resonance

Cited by 84 publications

References 29 publications

A well resolved ODMR triplet minus singlet spectrum of P680 from PSII particles

A well resolved ODMR triplet minus singlet spectrum of P680 from PSII particles

Modeling of the D1/D2 proteins and cofactors of the photosystem II reaction center: Implications for herbicide and bicarbonate binding

Similarity of primary radical pair recombination in photosystem II and bacterial reaction centers

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