Temperature dependence of the primary electron transfer in photosynthetic reaction centers from Rhodobacter sphaeroides

Lauterwasser, Christoph; Finkele, Ulrich; Scheer, Hugo

doi:10.1016/0009-2614(91)80161-p

Cited by 104 publications

(67 citation statements)

References 28 publications

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“…Very recent emission experiments have shown that the 3 ps decay of P* seems to be a biphasic process with two time constants [8,9]. At all temperatures an additional subpicosecond component was detected in Rhodobacter sphaeroides having time constants of 0.3 ps to 0.9 ps for temperatures of 25 K to 300 K [10,11]. The same ultrafast component was found in RCs from Rhodopseudomonas viridis having a time constant of 0.65 ps at 300 K [5].…”

Section: Introductionmentioning

confidence: 72%

“…0.9 ps) is associated with the electron transfer from P+B A to P+H A (The assignment of ~3 = 200 ps to the transition of P+H A to P+Q;~, on the other hand, is generally accepted). Regarding the sub-picosecond kinetic ~'2, one trivial explanation could not be ruled out: All published experiments where a sub-picosecond kinetic (namely ~2) was observed, were done with detergenttreated preparations of isolated RCs [2,6,7,10]. It is not known whether the ultrafast absorption dynamics are altered by a preparation artifact during the isolation of the reaction centers from the chromatophores by detergents.…”

Section: Introductionmentioning

confidence: 99%

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Time-resolved spectroscopy of the primary photosynthetic processes of membrane-bound reaction centers from an antenna-deficient mutant of Rhodobacter capsulatus

Schmidt

Arlt

Hamm

et al. 1993

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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The primary photosynthetic reactions in whole membranes of the antenna-deficient mutant strain U43 (pTXA6-10) of Rhodobacter capsulatus are studied by transient absorption and emission spectroscopy with subpicosecond time resolution. Extensive similarities between the transient absorption data on whole membranes and on isolated reaction centers support the idea that the primary processes in isolated reaction centers are not modified by the isolation procedure.

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Section: Introductionmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Time-resolved spectroscopy of the primary photosynthetic processes of membrane-bound reaction centers from an antenna-deficient mutant of Rhodobacter capsulatus

Schmidt

Arlt

Hamm

et al. 1993

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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“…In this paper, we present kinetic absorption studies on RCs containing 132-hydroxy-BChl-a or [3-vinyl] system has been described in detail (19) are plotted for Apr = 920 nm, Apr = 785 nm, and Apr = 665 nm.…”

Section: P+b P+h-p+q- This Model Ismentioning

confidence: 99%

“…The observation of an additional, subpicosecond time constant in Rhodobacter sphaeroides (16)(17)(18)(19)(20) again raised the possibility of P+B-being a real intermediate according to P .…”

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confidence: 99%

Primary electron transfer kinetics in bacterial reaction centers with modified bacteriochlorophylls at the monomeric sites BA,B.

Finkele

Lauterwasser

Struck

et al. 1992

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

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The primary electron transfer has been investigated by femtosecond time-resolved absorption spectroscopy in two chemically modified reaction centers (RC) of Rhodobacter sphaeroides, in which the monomeric bacteriochlorophylls BA and BB have both been exchanged by 132-hydroxybacteriochlorophyll a or [3-vinylJ-132-hydroxybac-teriochlorophyll a. The kinetics of the primary electron transfer are not influenced by the 132-hydroxy modification. In RCs containing [3-vinyl]-132-hydroxybacteriochlorophyll a the primary rate is reduced by a factor of 10. HThe three known x-ray structures of bacterial reaction centers (RCs) show basically the same arrangement of the cofactors (see refs. 1-4). They form two branches [A (active) and B (inactive)], which are arranged in an approximate twofold symmetry. Surprisingly, the electron transfer (ET) has been found to proceed exclusively along the A branch (5-7). From the primary donor, P870 or P960, an electron is transferred to the acceptor quinone (QA) The structural arrangement of the chromophores suggests an ET via the two intervening pigments-i.e., the monomeric bacteriochlorophyll (BChl) BA and the bacteriopheophytin (BPhe) HAWhile there is general agreement that the BPhe HA is an intermediate electron acceptor (5-9), the role of the BChl BA located between the BChl dimer P and the BPhe HA is still controversially discussed. First studies with sufficient time resolution and an appropriate excitation wavelength led to the conclusion that the state P+B-(P, primary donor) is not a real intermediate in the ET (5,10,11). However, a direct ET from P* to HA over an edge-to-edge distance of '10 A can be accounted for only by a "superexchange" transfer via a virtual intermediate P+B-(12-15 Kinetic measurements were performed at T 298 K in cuvettes of 1-mm path length under stirring. The sample volume was 0.2-0.3 ml. The transmission was between T 10%o and 50% at A = 860 nm (80-25 ,uM The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

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“…It now is becoming accepted that electron transfer from P* to P ϩ H A Ϫ proceeds via the anion of the accessory Bchl, B A , located between P and H A . At room temperature P ϩ B A Ϫ is formed as a short-lived, intermediate with a lifetime of 0.9-1.5 ps (7)(8)(9)(10)(11). Charge separation is completed by electron transfer from P Until recently it generally was accepted that excitation of the RC bacteriopheophytins or monomeric Bchls resulted in downhill energy transfer to P within a few hundreds of femtoseconds, forming P* that drives charge separation (12)(13)(14)(15).…”

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confidence: 99%

Multiple pathways for ultrafast transduction of light energy in the photosynthetic reaction center of Rhodobacter sphaeroides

Brederode

Mourik

Stokkum

et al. 1999

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

112

107

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A pathway of electron transfer is described that operates in the wild-type reaction center (RC) of the photosynthetic bacterium Rhodobacter sphaeroides. The pathway does not involve the excited state of the special pair dimer of bacteriochlorophylls (P*), but instead is driven by the excited state of the monomeric bacteriochlorophyll (B A *) present in the active branch of pigments along which electron transfer occurs. Pump-probe experiments were performed at 77 K on membrane-bound RCs by using different excitation wavelengths, to investigate the formation of the charge separated state P ؉ H A ؊ . In experiments in which P or B A was selectively excited at 880 nm or 796 nm, respectively, the formation of P ؉ H A ؊ was associated with similar time constants of 1.5 ps and 1.7 ps. However, the spectral changes associated with the two time constants are very different. Global analysis of the transient spectra shows that a mixture of P ؉ B A ؊ and P* is formed in parallel from B A * on a subpicosecond time scale. In contrast, excitation of the inactive branch monomeric bacteriochlorophyll (B B ) and the high exciton component of P (P ؉ ) resulted in electron transfer only after relaxation to P*. The multiple pathways for primary electron transfer in the bacterial RC are discussed with regard to the mechanism of charge separation in the RC of photosystem II from higher plants.

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Temperature dependence of the primary electron transfer in photosynthetic reaction centers from Rhodobacter sphaeroides

Cited by 104 publications

References 28 publications

Time-resolved spectroscopy of the primary photosynthetic processes of membrane-bound reaction centers from an antenna-deficient mutant of Rhodobacter capsulatus

Time-resolved spectroscopy of the primary photosynthetic processes of membrane-bound reaction centers from an antenna-deficient mutant of Rhodobacter capsulatus

Primary electron transfer kinetics in bacterial reaction centers with modified bacteriochlorophylls at the monomeric sites BA,B.

Multiple pathways for ultrafast transduction of light energy in the photosynthetic reaction center of Rhodobacter sphaeroides

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