Different temperature dependencies of the charge recombination reaction in photoreaction centers isolated from different bacterial species

Mar, Ted; Vadeboncoeur, Christian; Gingras, G

doi:10.1016/0005-2728(83)90090-7

Cited by 12 publications

(7 citation statements)

References 20 publications

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“…When the sample temperature was raised above ~90 K, TADdark increased monotonically with increasing temperature, in agreement with previous reports (Parson, 1967;Loach et al, 1975; Hsi & Bolton, 1974;Mar et al, 1983). This increase was stable with time at each temperature and was completely reversible as the temperature was cycled.…”

Section: Resultssupporting

confidence: 92%

Electron-transfer kinetics in photosynthetic reaction centers cooled to cryogenic temperatures in the charge-separated state: evidence for light-induced structural changes

Kleinfeld¹,

Okamura²,

Fehér³

1984

Biochemistry

367

378

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We have compared the electron-transfer kinetics in reaction centers (RCs) cooled in the dark with those cooled under illumination (i.e., in the charge-separated state). Large differences between the two cases were observed. We interpreted these findings in terms of light-induced structural changes. The kinetics of charge recombination D+QA-----DQA in RCs containing one quinone were modeled in terms of a distribution of donor-acceptor electron-transfer distances. For RCs cooled under illumination the distribution broadened and shifted to larger distances compared to the distribution for RCs cooled in the dark. The model accounts for the nonexponential decay observed at low temperatures [McElroy, J. D., Mauzerall, D. C., & Feher, G. (1974) Biochim. Biophys. Acta 333, 261-277; Morrison, L.E., & Loach, P.A. (1978) Photochem. Photobiol. 27, 751-757]. A possible physiological role of the structural changes is an enhanced charge stabilization. For RCs with two quinones, the recombination kinetics D+QAQB-----DQAQB were found to be strongly temperature dependent. This was interpreted in terms of temperature-dependent transitions between structural states [Agmon, N., & Hopfield, J.J. (1983) J. Chem. Phys. 78, 6947-6959]. This interpretation requires that these transitions occur at cryogenic temperatures on a time scale t greater than or approximately 10(3) s. The electron transfer from QA- to QB was found to not take place in RCs cooled in the dark (tau ABdark greater than 10(-1) s). In RCs cooled under illumination, we found tau ABlight less than 10(-3) s. We suggest the possibility that the drastic decrease in tau AB observed in RCs cooled under illumination is due to the trapping of a proton near QB-.

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Section: Resultssupporting

confidence: 92%

Electron-transfer kinetics in photosynthetic reaction centers cooled to cryogenic temperatures in the charge-separated state: evidence for light-induced structural changes

Kleinfeld¹,

Okamura²,

Fehér³

1984

Biochemistry

367

378

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“…[14][15][16] The reaction scheme shown in Figure 1 applies to RCs which contain a single ubiquinone acceptor QA. The charge recombination (CR) reaction P+QA--* PQA, with rate constant kr, depends weakly on temperature, increasing by a factor of 4 as the temperature is lowered from room temperature to 77 K in glycerol/buffer solution.12' 18 The charge separation (CS) which generates the P+QA-state involves at least two rapid 0022-3654/93/2097-6304$04.00/0 cm'1 eV Figure 1. Reaction scheme for quinone-containing RCs.…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of the electric field modulation of electron-transfer rates: charge recombination in photosynthetic reaction centers

Franzen¹,

Boxer²

1993

J. Phys. Chem.

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The rates of electron-transfer reactions can be systematically varied by application of external electric fields.The electric field effect on the charge recombination rate constant of the state P+QA-in photosynthetic reaction centers has been measured in polymer film samples at a number of temperatures. This extends an earlier study at 80 K in which a small field-induced slowing of the rate constant was reported [Franzen, S.; Goldstein, R. F.; Boxer, S . G. J. Phys. Chem. 1990, 94, 5135-51491. At temperatures greater than 160 K, evidence is presented for an electric-field-induced activated recombination pathway similar to that observed in reaction centers which have nonnative quinones of low reduction potential substituted for ubiquinone. However, it is shown that this pathway alone cannot account for the electric-field-induced changes in kinetics observed at higher temperatures. The data analysis used to obtain the log(ket) vs AGet curve at 80 K is extended to include changes in the steady-state population of P+QA-observed at higher temperatures with a continuous wave probe beam. This field dependence is analyzed in terms of electron-transfer theory including the entropy of reaction and the temperature dependences of the reorganization energy and the local field correction. The data and analysis suggest that a temperature-dependent reorganization energy is associated with solvation of the P Q Adipole.

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“…Using a pulsed actinic flash to oxidize the To see if there is any correlation between the fluorescence properties of the ANS and the rate of the primary back reaction as a function of temperature, the kinetics of the back reaction and the ANS fluorescence were measured under identical conditions. Since we found that the change in absorbance of the photoreaction center caused a change in the ANS fluorescence intensity, we followed the rate of the back reaction by the rate of change in the ANS fluorescence instead of the usual method by the rate of change in the absorbance of the photoreaction center [15]. This insures that both the kinetics of the back reaction and the fluorescence of ANS are measured under identical conditions.…”

Section: Resultsmentioning

confidence: 99%

“…rubrum [6,9,15]. A structural change involving the intermolecular distance between the reduced ubiquinone and the oxidized bacteriochlorophy molecules has been proposed [5; 6, 8, 9, 15].…”

Section: Discussionmentioning

confidence: 99%

“…Many theoretical analyses [3,5,7,9,12,21] have been done to explain this phenomenon. We [15] found that although the temperature dependence of the back reaction in photoreaction centers isolated from Ectothiorhodospira sp. can be interpreted in terms of an activationless electron transfer model formulated by Jortner [9], the temperature dependency of the back reaction in photoreaction centers from Rs.…”

Section: Introductionmentioning

confidence: 99%

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Use of 8-analino-1-naphthalene sulfonate as a monitor for possible phase transition involving water at low temperatures in photoreaction center from Rhodospirillum rubrum

Mar

Bouchard

1984

Photosynth Res

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The increase in the rate of the primary back reaction on cooling the photoreaction center from Rhodospirillum rubrum was interpreted in terms of a model in which the peculiar temperature dependence of the rate results from a phase transition involving water. The primary back reaction is defined as the return of the electron from the reduced primary ubiquinone to the oxidized bacteriochlorophyll molecules following illumination. The dye 8-anilino-1-naphthalene sulfonate was used to detect the state of the water solvent as it transforms on cooling from a liquid to a solid glass. We inferred from studies with air-dried films of photoreaction center that the water which may be responsible for the unusual temperature dependence of the rate of the primary back reaction is not on the surface but is bound within the photoreaction center protein.

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Different temperature dependencies of the charge recombination reaction in photoreaction centers isolated from different bacterial species

Cited by 12 publications

References 20 publications

Electron-transfer kinetics in photosynthetic reaction centers cooled to cryogenic temperatures in the charge-separated state: evidence for light-induced structural changes

Electron-transfer kinetics in photosynthetic reaction centers cooled to cryogenic temperatures in the charge-separated state: evidence for light-induced structural changes

Temperature dependence of the electric field modulation of electron-transfer rates: charge recombination in photosynthetic reaction centers

Use of 8-analino-1-naphthalene sulfonate as a monitor for possible phase transition involving water at low temperatures in photoreaction center from Rhodospirillum rubrum

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