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Huber, Martina

doi:10.1023/a:1005831828249

Cited by 30 publications

(18 citation statements)

References 88 publications

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“…1). This can be accomplished, for instance, by introducing or disrupting H bonds of the cofactors or by changing the ligation of the Mg in the chlorophyll macrocycles of the primary donor P. In this context, it is particularly interesting to systematically study the influence of the environment of the primary donor, since Pis generally considered to playa key role in the origin of the unidirectionality of the primary charge-separation steps [1,16,59,61,62].…”

Section: Ghz Cw Epr On P8~5 Of Mutant Rcs From R Sphaeroidesmentioning

confidence: 99%

“…For example, in the course of X-band ENDOR and TRIPLE (electron-nuclear-nuclear triple resonance) [69] experiments on the R-26.1 mutant and wild-type RCs [1,61,62,70], a pronounced asymmetry of 2:1 of the spin density distribution over the two dimer halves in Pff6+5 was determined, favoring the BChl axially ligated by the L subunit. The electronic structure of Pff6+5 in the R-26.1 mutant RC turned out to be similar to the carotenoid-containing wild-type RC [70].…”

Section: Ghz Cw Epr On P8~5 Of Mutant Rcs From R Sphaeroidesmentioning

confidence: 99%

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High-field EPR, ENDOR and ELDOR on bacterial photosynthetic reaction centers

et al. 2007

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We report on recent 95 and 360 GHz high-field electron paramagnetic resonance (EPR), electron-nuclear double resonance (ENDOR) and pulsed electron-electron double resonance (PELDOR) studies of wild-type and mutant reaction centers (RCs) from the photosynthetic bacterium Rhodobacter sphaeroides. Taking advantage of the excellent spectral and temporal resolution of EPR at 95 and 360 GHz, the electron-transfer (ET) cofactors radical ions and spin-correlated radical pairs were characte¡ by their g-and hyperfine-tensor components, their anisotropic T, relaxation as well as by the dipolar interaction between P~~sQ~-radical pairs. The goal of these studies is to better understand the dominant factors determining the specificity and directionality of transmembrane ET processes in photosynthetic RC proteins. In particular, our multifrequency experiments elucidate the subtle cofactor-protein interactions, which are essential for fine-tuning the ET characteristics, e.g., the unidirectionality of the light-induced ET pathways along the A branch of the RC protein. By our high-field techniques, frozen-solution RCs of novel site-specific single and double mutants of R. sphaeroides were studied to modulate the ET characteristics, e.g., even to the extent that dominant B branch ET prevails. The presented multifrequency EPR work culminates in first 360 GHz ENDOR results from organic nitroxide radicals as well as in first 95 GHz high-field PELDOR results from orientationally selected spin-polarized radical pairs Ps which a|low to determine the full geometrical structure of the pairs even in frozen-solution RCs.

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Section: Ghz Cw Epr On P8~5 Of Mutant Rcs From R Sphaeroidesmentioning

confidence: 99%

Section: Ghz Cw Epr On P8~5 Of Mutant Rcs From R Sphaeroidesmentioning

confidence: 99%

High-field EPR, ENDOR and ELDOR on bacterial photosynthetic reaction centers

et al. 2007

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“…Furthermore, first single crystal ENDOR spectra of D T are shown. A short outline of the results of the present study has been published previously [2]. A diseussion of ENDOR lines observed at low frequencies, which are attributed to transitions of the 14N nuclei of the systems, is given in [11].…”

Section: Introductionmentioning

confidence: 95%

“…The electronic structure of D has been suggested to playa role in the unidirectionality [1], since the two BChl molecules which constitute D (D L and DM) are centrally located with respect to the active (A) and inactive (B) branches. One way to probe the electronic structure of D is through EPR/ENDOR methods on paramagnetic states of D (for recent reviews, see [2,3] for example). Local information on MO coefficients can be obtained by measuring the hyperfine (hf) interaction of the unpaired electron with the nuclei.…”

Section: Introductionmentioning

confidence: 99%

ENDOR on the triplet state of the primary electron donor in the photosynthetic bacteriumRhodobacter sphaeroides — One step forward in a still unfinished story

et al. 1997

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The electronic structure of the primary electron donor (D) of the photosynthetic bacterium Rhodobacter sphaeroides is investigated by ENDOR in the photoinduced triplet state of D. Hyperfine (hi') splittings of the triplet state measured on frozen solutions are given and compared to the results obtained earlier (Lendzian F., van Willigen H., Sastry S., M6bius K., Scheer H., Feick R.: Chem. Phys. Lett. 118, 145 (1985)). The hf splittings found are consistent with a model of ma asymmetric spin density distribution over the two baeteriochlorophyll moleeules which constitute D, suggesting a mirror image symmetry of HOMO and LUMO coefficients. This could be relevant for electron transfer, in particular tmidirectionality in the reaction center (RC). The first triplet state ENDOR experiments on single crystals of RC's are also reported.

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“…Since the first high‐resolution X‐ray crystal structure of PRC of Rhodopseudomonas viridis ( Rh. viridis ) was resolved by Deisenhofer 1a, 1b, studies on the mechanism of photosynthesis in PRC reached a new molecular level and a lot of important results have been published 2–10. In the case of large‐scale protein molecules, theoretical studies on proteins in PRC were rough.…”

Section: Introductionmentioning

confidence: 99%

Quantum chemistry study of proteins in bacterial photosynthetic reaction center

Shen

Zhang

2001

Int J of Quantum Chemistry

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Quantum chemistry study on proteins L and M in the Rhodopseudomonas viridis (Rh. viridis) photosynthetic reaction center (PRC) are presented. The calculations were performed at ab initio level with Clementi minimal basis set by means of the overlapping‐dimer approximation (ODA)–extended negative factor counting (ENFC) method. Additional point charges were added to individual residues to simulated ionized aqueous environment of the proteins in the calculations. Meanwhile, the electronic structure of protein complex MH (protein M plus the α‐helix segment of protein H) was studied as well to examine the weak interaction between proteins M and H. As the first case of global quantum chemistry calculation for proteins in PRC, details of the electronic structure and the influence of proteins on the electron transfer process (ET) were studied. Moreover, new three‐dimensional structure plots of subunit L and M were given based on the distribution of the components of frontier orbitals in order to more clearly understand the structure–function relationship of the proteins in electron transfer reactions. Calculation results indicated that the components of frontier orbitals are extremely localized at individual residues. Amino acid residues, having contributed to the frontier orbitals of protein L, are located at the flexible random area of L, while those having contributed to the frontier orbitals of protein M are located at the rigid α‐helix area. This asymmetry of proteins L and M provides new understanding the ET reaction that takes place mainly along branch L in the PRC of Rh. viridis. Meanwhile, there is frontier orbital localized amino acid distribution around the V‐shaped pocket areas of protein L (M) that were expected to have an important interaction with QA (QB). All results indicate that protein provided a heterogeneous environment for pigment molecules and some important interaction between protein residues and pigment molecules are worthy of further investigation. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 83: 30–40, 2001

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Cited by 30 publications

References 88 publications

High-field EPR, ENDOR and ELDOR on bacterial photosynthetic reaction centers

High-field EPR, ENDOR and ELDOR on bacterial photosynthetic reaction centers

ENDOR on the triplet state of the primary electron donor in the photosynthetic bacteriumRhodobacter sphaeroides — One step forward in a still unfinished story

Quantum chemistry study of proteins in bacterial photosynthetic reaction center

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