Electron-spin polarization in the donor triplet state of bacterial photosynthetic reaction centers. I. Microsecond time-resolved EPR of Rhodopseudomonas viridis reaction centers

Wijk, F.G.H. van; Schaafsma, T.J.

doi:10.1016/0005-2728(88)90241-1

Cited by 11 publications

(2 citation statements)

References 27 publications

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“…k2 was estimated as 0. 05-0.1 ns'1 from the rate of carotenoid triplet formation (Takahashi et al, 1987), which occurs most likely via 3P680 (Booth et al, 1990), and from the rate of spin dephasing of the primary charge pair in purple bacteria (Hoff, 1987;van Wijk & Schaafsma, 1988). From the room temperature decay rate of 3P680 (Durrant et al, 1990) k¡ was estimated as 1 ms'1.…”

Section: Discussionmentioning

confidence: 99%

Spectroscopic characterization of triplet forming states in photosystem II

Vass

Styring²

1992

Biochemistry

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Fluorescence and electron paramagnetic resonance (EPR) measurements have been applied to characterize chlorophyll triplet formation in the reaction center of photosystem II (PSII). A highly triplet forming state was generated in PSII membranes by chemical double reduction of the primary electron acceptor QA. In triplet forming PSII centers, the steady-state yield of chlorophyll fluorescence decreased to about 70% of the maximal fluorescence yield observed in closed PSII centers in which QA is singly reduced. The results are well interpreted in the framework of a model where the charge state of QA electrostatically controls the yield of primary charge separation [Schatz, G. H., Brock, H., & Holzwarth, A. R. (1988) Biophys. J. 54, 397-405]. Thus, high triplet yield and decreased, although still quite high, fluorescence indicate a charge-neutralized state of PSII in which QA is singly or doubly reduced and protonated or absent. The EPR signal of the triplet primary chlorophyll donor, 3P680, is suppressed by illumination at 77 K concomitant with the formation of a cationic radical (g = 2.0025-2.0027, and 0.92 mT wide) that is stable in the dark. This is attributed to the oxidation of an accessory chlorophyll (Chl) in the vicinity of P680. Electrostatic repulsion between Chl+ and P680+ is likely to prevent primary charge separation, and in turn triplet formation, providing a further example of electrostatic control of primary charge separation. The triplet P680 EPR signal is also suppressed in the presence of oxygen. This effect, which is almost completely reversible by removing the oxygen, is attributed to the interaction of triplet P680 with triplet O2.

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Section: Discussionmentioning

confidence: 99%

Spectroscopic characterization of triplet forming states in photosystem II

Vass

Styring²

1992

Biochemistry

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“…The research was started with a systematic study of the triplet state of chlorophyll and related molecules. Subsequently electron-spin polarization in the donor triplet state of bacterial photosynthetic reaction centers had been investigated (69).…”

Section: The Agricultural University Of Wageningenmentioning

confidence: 99%

Electron Paramagnetic Resonance in the Netherlands

Boer¹

1998

Foundations of Modern EPR

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Photoexcited Triplet State Kinetics Studied by Electron Paramagnetic Resonance Spectroscopy

2016

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Following the first evidence of the triplet character of the optically excited phosphorescent state of naphthalene by Hutchison and Mangum in 1958, electron paramagnetic resonance (EPR) spectroscopy has become widely used to study and understand the properties and kinetic characteristics of excited triplet states. This minireview gives an overview over EPR techniques based on continuous microwave methods using lock-in or direct detection as well as pulsed EPR methods with respect to their suitability for kinetic studies of excited triplet states. A short historical overview of the experimental and theoretical developments in this field of research as well as of the triplet systems studied, with a final focus on fullerenes, is given. This may help newcomers to the field as a guide to the relevant literature.

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Electron-spin polarization in the donor triplet state of bacterial photosynthetic reaction centers. I. Microsecond time-resolved EPR of Rhodopseudomonas viridis reaction centers

Cited by 11 publications

References 27 publications

Spectroscopic characterization of triplet forming states in photosystem II

Spectroscopic characterization of triplet forming states in photosystem II

Electron Paramagnetic Resonance in the Netherlands

Photoexcited Triplet State Kinetics Studied by Electron Paramagnetic Resonance Spectroscopy

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