Electroluminescence

Gorkom, Hans J. van

doi:10.1007/bf00041001

Cited by 10 publications

(4 citation statements)

References 57 publications

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“…Transthylakoid electric fields also influence recombination reactions in PSI reaction centers ( van Gorkom, 1996 ). It is thought that P 700 triplet formation is minimized in PSI by the presence of the higher potential quinone in PsaA, making this side of the reaction center the safe charge recombination pathway ( Rutherford et al, 2012 ).…”

Section: Discussionmentioning

confidence: 99%

Limitations to photosynthesis by proton motive force-induced photosystem II photodamage

Davis

Kanazawa

Schöttler

et al. 2016

eLife

100

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The thylakoid proton motive force (pmf) generated during photosynthesis is the essential driving force for ATP production; it is also a central regulator of light capture and electron transfer. We investigated the effects of elevated pmf on photosynthesis in a library of Arabidopsis thaliana mutants with altered rates of thylakoid lumen proton efflux, leading to a range of steady-state pmf extents. We observed the expected pmf-dependent alterations in photosynthetic regulation, but also strong effects on the rate of photosystem II (PSII) photodamage. Detailed analyses indicate this effect is related to an elevated electric field (Δψ) component of the pmf, rather than lumen acidification, which in vivo increased PSII charge recombination rates, producing singlet oxygen and subsequent photodamage. The effects are seen even in wild type plants, especially under fluctuating illumination, suggesting that Δψ-induced photodamage represents a previously unrecognized limiting factor for plant productivity under dynamic environmental conditions seen in the field.DOI: http://dx.doi.org/10.7554/eLife.16921.001

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Section: Discussionmentioning

confidence: 99%

Limitations to photosynthesis by proton motive force-induced photosystem II photodamage

Davis

Kanazawa

Schöttler

et al. 2016

eLife

100

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“…Their quenching has been discussed in relation to the seeming paradox that the release of fluorescence quenching F v in a single turnover flash (STF) in which all Q A is reduced, is substantially below that measured in multi-turnover light pulses (MTF) (Kramer et al 1995;Samson and Bruce 1996;Kolber et al 1998;Vasilev and Bruce 1998;Samson et al 1999;Koblizek et al 2001;Vredenberg et al 2005). The documented effect of electric fields on the fluorescence yield (Vos et al 1991;van Gorkom 1996;Vredenberg 2004) is assumed to be comparatively small in the time domain <2 ms, and is not considered here.…”

Section: Introductionmentioning

confidence: 99%

On the chlorophyll a fluorescence yield in chloroplasts upon excitation with twin turnover flashes (TTF) and high frequency flash trains

2007

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Chlorophyll fluorescence is routinely taken as a quantifiable measure of the redox state of the primary quinone acceptor Q A of PSII. The variable fluorescence in thylakoids increases in a single turnover flash (STF) from its low dark level F o towards a maximum F m STF when Q A becomes reduced. We found, using twin single turnover flashes (TTFs) that the fluorescence increase induced by the first twin-partner is followed by a 20-30% increase when the second partner is applied within 20-100 ls after the first one. The amplitude of the twin response shows a period-of-four oscillation associated with the 4-step oxidation of water in the Kok cycle (S states) and originates from two different trapped states with a life time of 0.2-0.4 and 2-5 ms, respectively. The oscillation is supplemented with a binary oscillation associated with the two-electron gate mechanism at the PSII acceptor side. The F(t) response in high frequency flash trains (1-4 kHz) shows (i) in the first 3-4 flashes a transient overshoot 20-30% above the F m STF = 3*F o level reached in the 1st flash with a partial decline towards a dip D in the next 2-3 ms, independent of the flash frequency, and (ii) a frequency independent rise to F m = 5*F o in the 3-60 ms time range. The initial overshoot is interpreted to be due to electron trapping in the S 0 fraction with Q B -nonreducing centers and the dip to the subsequent recovery accompanying the reoxidation of the double reduced acceptor pair in these RCs after trapping. The rise after the overshoot is, in agreement with earlier findings, interpreted to indicate a photo-electrochemical control of the chlorophyll fluorescence yield of PSII. It is anticipated that the double exciton and electron trapping property of PSII is advantageous for the plant. It serves to alleviate the depression of electron transport in single reduced Q B -nonreducing RCs, associated with electrochemically coupled proton transport, by an increased electron trapping efficiency in these centers.Keywords Chlorophyll a Á Fluorescence quenching Á Q B -nonreducing center Á Single turnover excitation Á Twin turnover excitation Á Three state trapping mechanism (TSTM)

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“…(Rappaport et al 1994;Haumann and Junge 1994) for the most recent data on the kinetics of these reactions. Vos et al (1991) have studied the stabilization processes in PSII by means of electroluminescence (EL) (Arnold and Azzi 1971;Ellenson and Sauer 1976;van Gorkom, 1996). This is chlorophyll fluorescence due to reversal of the photosynthetic charge separation by an electric field.…”

Section: Introductionmentioning

confidence: 99%

Effect of the redox state of QB on electric field-induced charge recombination in Photosystem II

Hemelrijk

Gorkom

1996

Photosynth Res

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Electric field-induced charge recombination in Photosystem II (PS II) was studied in osmotically swollen spinach chloroplasts ('blebs') by measurement of the concomitant chlorophyll luminescence emission (electroluminescence). A pronounced dependence on the redox state of the two-electron gate QB was observed and the earlier failure to detect it is explained. The influence of the QB/QB (-) oscillation on electroluminescence was dependent on the redox state of the oxygen evolving complex; at times around one millisecond after flash illumination a large effect was observed in the states S2 and S3, but not in the state 'S4' (actually Z(+)S3). The presence of the oxidized secondary electron donor, tyrosine Z(+), appeared to prevent expression of the QB/QB (-) effect on electroluminescence, possibly because this effect is primarily due to a shift of the redox equilibrium between Z/Z(+) and the oxygen evolving complex.

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Electroluminescence

Cited by 10 publications

References 57 publications

Limitations to photosynthesis by proton motive force-induced photosystem II photodamage

Limitations to photosynthesis by proton motive force-induced photosystem II photodamage

On the chlorophyll a fluorescence yield in chloroplasts upon excitation with twin turnover flashes (TTF) and high frequency flash trains

Effect of the redox state of QB on electric field-induced charge recombination in Photosystem II

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