Sub‐picosecond measurements of primary electron transfer in<i>Rhodopseudomonas viridis</i>reaction centers using near‐infrared excitation

Wasielewski, Michael R.; Tiede, David M.

doi:10.1016/0014-5793(86)80845-6

Cited by 79 publications

(26 citation statements)

References 18 publications

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“…2). These kinetics are almost identical to the analogous reaction in photosynthetic bacterial reaction center [17][18][19]. Takahashi et al [201 and Danielius et al [211 have measured at 5 °C a 32 ns lifetime for P680 ÷ Pheo-(Eqn.…”

Section: Introductionsupporting

confidence: 55%

Chlorophyll a fluorescence lifetime distributions in open and closed Photosystem II reaction center preparations

Govindjee

Ven

Preston³

et al. 1990

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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We have measured the decay of chlorophyll a fluorescence at 4 °C under anaerobic conditions in stabilized photosystem !I reaction center complex isolated from spinach, using multifrequeucy (2-400 MHz) cross-correlation phase fluorometry. Examination of our data shows that although the fluorescence decay of open reaction centers (i.e., when both the electron donor P-680 and the electron acceptor pheophytin are capable of engaging in charge separation) can he analyzed as a multiexponential decay, another representation of the data is obtained when the decay is analyzed using a continuous distribution of lifetimes. [478][479][480][481][482][483][484][485][486] for the DI-D2-cytochrome /}-559 complex, obtained for F682 at 4°C by a time-resolved photon-counting spectrofiuorometer. When the reaction centers are closed by pretreatment with sodium dithionite and methyl viologen followed by exposure to laser excitation, conditions known to result in accumulation of reduced pheophytin, a dramatic decrease in the contribution of the slow lifetime component(s) is observed. These results suggest that the slow distribution lifetime component(s) in the 5-20 ns range originate(s) in the back reaction of the charge separated state. On the other hand, the fast lifetime component(s) in the picosecond range may he only partially related to the charge separation, since no dramatic change is observed upon closure of the reaction center. Perhaps, this component is related, in part, to the excitation energy migration among the various chromophores in the reaction center preparations.

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Section: Introductionsupporting

confidence: 55%

Chlorophyll a fluorescence lifetime distributions in open and closed Photosystem II reaction center preparations

Govindjee

Ven

Preston³

et al. 1990

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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“…sphaeroides and Rps. viridis RCs have been based largely on the finding of identical kinetics for the decay of P* and the formation of P+BPhF~ [4][5][6][7][8]. Our spectral data provide a new measure of the extent to which the conversion of P* to P+BPhF~ may involve an intermediate state.…”

Section: Mechanism Of the Initial Electron Transfer Reactionmentioning

confidence: 94%

Subpicosecond characterization of the optical properties of the primary electron donor and the mechanism of the initial electron transfer in Rhodobacter capsulatus reaction centers

Kirmaier

Holten

1988

FEBS Letters

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The optical difference spectrum of the excited primary electron donor, P*, in Rb. capsulatus reaction centers has been measured 600 fs after a 350‐fs flash at 870 nm. The spectrum is characterized by bleaching in the ground state absorption bands at 855 and 600 nm, and a weak featureless transient absorption in between. The lack of significant (if any) bleaching at 800 nm indicates that P does not contribute appreciable oscillator strength to the 800‐nm ground state absorption band. The conversion of P* to P+BPH− L is accompanied by isosbestic points in the transient difference spectra at 765 and 798 nm. The existence of the longer‐wavelength isosbestic point, occurring essentially at the near‐infrared absorbance maximum of the accessory BChls, provides compelling evidence that if state P*BChl− L forms, its transient concentration is exceedingly small. At certain wavelengths in the near‐infrared the absorption changes develop somewhat more slowly than the rate at which P* decays, a finding that may reflect a contribution from readjustments in the pigment‐protein complex in response to electron transfer.

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“…viridis no transient bleaching at 830 nm lasting more than 100 fs can be observed upon direct excitation within the Qy absorption band of P with 150-fs pulses and we have given conclusive evidence that in this system, like in reaction centers from Rps. sphaeroides, the state P+HL was generated directly from P* with a time constant of 2.8 f 0.2 ps ([17], see also [22,23] fig.3 to demonstrate the striking similarities in the kinetics of the transient absorbance changes for these two species of purple bacteria.…”

Section: Initial Electron Transfermentioning

confidence: 99%

The absence of a spectroscopically resolved intermediate state P⁺B⁻in bacterial photosynthesis

et al. 1986

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Reaction centers from the photosynthetic bacterium Rhodopseudomonas sphaeroides have been excited either in the bacteriopheophytin band at 760 nm or in the accessory bacteriochlorophyll (B) band around 800 nm with laser pulses of 150 fs duration. Upon monitoring in the absorption band of the primary donor (P) at 860 nm, ultrafast energy transfer is observed which leads to the excited state of P in less than 100 fs. A transient bleaching recovering in 400 ± 100 fs is specifically detected upon excitation and observation in the 800 nm absorption band of B. However, upon direct excitation of P in the near infrared and using either normal or borohydride‐treated reaction centers, we have found no spectral or kinetic evidence indicating the presence of a transient intermediate state such as P+B−.

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Sub‐picosecond measurements of primary electron transfer inRhodopseudomonas viridisreaction centers using near‐infrared excitation

Cited by 79 publications

References 18 publications

Chlorophyll a fluorescence lifetime distributions in open and closed Photosystem II reaction center preparations

Chlorophyll a fluorescence lifetime distributions in open and closed Photosystem II reaction center preparations

Subpicosecond characterization of the optical properties of the primary electron donor and the mechanism of the initial electron transfer in Rhodobacter capsulatus reaction centers

The absence of a spectroscopically resolved intermediate state P⁺B⁻in bacterial photosynthesis

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Sub‐picosecond measurements of primary electron transfer inRhodopseudomonas viridisreaction centers using near‐infrared excitation

Cited by 79 publications

References 18 publications

Chlorophyll a fluorescence lifetime distributions in open and closed Photosystem II reaction center preparations

Chlorophyll a fluorescence lifetime distributions in open and closed Photosystem II reaction center preparations

Subpicosecond characterization of the optical properties of the primary electron donor and the mechanism of the initial electron transfer in Rhodobacter capsulatus reaction centers

The absence of a spectroscopically resolved intermediate state P+B−in bacterial photosynthesis

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The absence of a spectroscopically resolved intermediate state P⁺B⁻in bacterial photosynthesis