TEMPERATURE DEPENDENCE OF DELAYED LIGHT EMISSION IN THE 6 to 340 MICROSECOND RANGE AFTER A SINGLE FLASH IN CHLOROPLASTS

Jursinic, Paul A.

doi:10.1111/j.1751-1097.1977.tb07541.x

Cited by 73 publications

(25 citation statements)

References 69 publications

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“…They are documented to be in the range of 50 -90%. For instance, the light harvesting to charge separation efficiency is in the range of 84 -90% for photosystem II of higher plants [6,7].…”

Section: Introductionmentioning

confidence: 99%

Photosynthetic light harvesting: excitons and coherence

Fassioli

Dinshaw

Arpin

et al. 2014

J. R. Soc. Interface.

263

297

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Photosynthesis begins with light harvesting, where specialized pigmentprotein complexes transform sunlight into electronic excitations delivered to reaction centres to initiate charge separation. There is evidence that quantum coherence between electronic excited states plays a role in energy transfer. In this review, we discuss how quantum coherence manifests in photosynthetic light harvesting and its implications. We begin by examining the concept of an exciton, an excited electronic state delocalized over several spatially separated molecules, which is the most widely available signature of quantum coherence in light harvesting. We then discuss recent results concerning the possibility that quantum coherence between electronically excited states of donors and acceptors may give rise to a quantum coherent evolution of excitations, modifying the traditional incoherent picture of energy transfer. Key to this (partially) coherent energy transfer appears to be the structure of the environment, in particular the participation of non-equilibrium vibrational modes. We discuss the open questions and controversies regarding quantum coherent energy transfer and how these can be addressed using new experimental techniques.

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“…They are documented to be in the range of 50 -90%. For instance, the light harvesting to charge separation efficiency is in the range of 84 -90% for photosystem II of higher plants [6,7].…”

Section: Introductionmentioning

confidence: 99%

Photosynthetic light harvesting: excitons and coherence

Fassioli

Dinshaw

Arpin

et al. 2014

J. R. Soc. Interface.

263

297

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“…Chl d gains light energy at longer wavelengths and with a lowered redox potential, by ∼80 mV, compared with that of Chl a in Synechocystis sp. PCC 6803 (hereafter referred to as Synechocystis) and spinach (7)(8)(9)(10)(11). However, the overall conditions for the water-cleavage reaction are satisfied even with the difference in the redox potentials (12).…”

mentioning

confidence: 99%

Redox potentials of primary electron acceptor quinone molecule (Q _A ) ⁻ and conserved energetics of photosystem II in cyanobacteria with chlorophyll a and chlorophyll d

Allakhverdiev

Watabe

Kojima

et al. 2011

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

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In a previous study, we measured the redox potential of the primary electron acceptor pheophytin (Phe) a of photosystem (PS) II in the chlorophyll d-dominated cyanobacterium Acaryochloris marina and a chlorophyll a-containing cyanobacterium, Synechocystis. We obtained the midpoint redox potential (E m ) values of −478 mV for A. marina and −536 mV for Synechocystis. In this study, we measured the redox potentials of the primary electron acceptor quinone molecule (Q A ), i. ) of A. marina was determined to be +64 mV without the Mn cluster and was estimated to be −66 to −86 mV with a Mn-depletion shift (130-150 mV), as observed with other organisms. The E m (Phe a/Phe a − ) in Synechocystis was measured to be −525 mV with the Mn cluster, which is consistent with our previous report. The Mn-depleted downshift of the potential was measured to be approximately −77 mV in Synechocystis, and this value was applied to A. marina (−478 mV); the E m (Phe a/Phe a − ) was estimated to be approximately −401 mV. These values gave rise to a ΔG PhQ of −325 mV for A. marina and −383 mV for Synechocystis. In the two cyanobacteria, the energetics in PS II were conserved, even though the potentials of Q A − and Phe a − were relatively shifted depending on the special pair, indicating a common strategy for electron transfer in oxygenic photosynthetic organisms.photosynthesis | photochemical reaction C hlorophylls (Chls) are key pigments for photosynthesis, and oxygenic photosynthetic organisms containing Chls are found all over the world-they sustain all terrestrial life through the primary production of organic molecules and the production of oxygen. Chl a and its derivatives, pheophytin (Phe) a and Chl a epimer (Chl a′), are used as the electron transfer components in photosystem (PS) II and PS I, respectively, except for in two taxonomic groups, marine cyanobacteria Prochlorococcus spp. containing divinyl-Chl a (1) and marine cyanobacteria Acaryochloris spp. containing Chl d (2). Consequently, experimental and theoretical analyses of the electron transfer system in oxygenic photosynthesis have been exclusively performed in Chl a-containing organisms, and the basic concept of the photosynthetic electron flow has been constructed on the basis of Chl a. However, our understanding of photosynthetic electron transfer is not yet complete because the reaction systems with divinyl-Chl a and Chl d have not been fully analyzed as yet.Since the discovery of Chl d in Acaryochloris marina in 1996 (3, 4), questions have arisen on the whether the electron transfer system in this organism is significantly different from those with Chl a. Interestingly, the functional "special pair" are Chl d molecules in the reaction centers of PS I and II in A. marina (5, 6); however, in PS II, Phe a is the primary electron acceptor. Chl d gains light energy at longer wavelengths and with a lowered redox potential, by ∼80 mV, compared with that of Chl a in Synechocystis sp. PCC 6803 (hereafter referred to as Synechocystis) and spinach (7-11). However, the overall ...

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“…9 to d by the data are 10-20% of 4', which are not unreasonable considering the uncertainty in the absorption coefficient. The standard free-energy changes in the primary steps of photo- [10] synthesis have been estimated by delayed light emission experiments (14 To summarize, if the free-energy requirements of the primary steps of photosynthesis are as high as 1.1-1.2 eV, then the low-intensity shutoff as well as the red drop may be due to a reaction shutoff at depth in the sample due to dilution of the radiation. The fate of the unused photons is not indicated.…”

Section: Yield and Red Dropmentioning

confidence: 99%

Alternative perspective on photosynthetic yield and enhancement

Warner¹,

Berry²

1987

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

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In the traditional Z scheme of photosynthesis the Emerson effects of red drop (decline in yield of photosynthesis in far-red light) and enhancement (of far-red yield by supplementary short-wavelength light) are taken to be evidence for the coupling in series of two photosystems that absorb unsymmetrically in the far-red region of the spectrum. An alternative explanation for red drop and enhancement is proposed here that does not invoke the series-coupling hypothesis. It is suggested that the Emerson effects may be due to the drop in intensity of radiation from sample absorption, which causes a photochemical loss when the reaction shuts off at depth in the medium. The effects of oxygen, carbon dioxide, and temperature on the yield may also be interpreted in terms of this model.In the traditional Z scheme of photosynthesis, reduction of ferredoxin by electrons donated from water is mediated by the coupling in series of photosystems I and II (PSI and PSII, respectively). Questions concerning the series coupling model arose when Rurainski and Hoch (1) found that magnesium salts increase the rate of NADP+ reduction while simultaneously decreasing the rate of P700 turnover. Melis and Brown (2) showed that the number ratio of PSII/PSI centers varies widely in different chloroplast subfragments. Anderson and Andersson (3) showed that PSI centers are concentrated in the stromal lamellae, whereas the PSII centers are found mostly in the appressed grana. Arnon et al. (4,5) demonstrated photoreduction of ferredoxin by water in the presence of inhibitors that block electron transport through plastoquinone. They suggested that the two photosystems are not coupled in series.It was the observation by Emerson et al. (6) of the decline in yield of photosynthesis in far-red light (red drop) and the enhancement of the far-red yield by supplementary shortwavelength light that provided much of the original motivation for the series-coupling model (7). Here we propose an alternative explanation for red drop and enhancement that does not require series coupling of the photosystems. The model developed below is not incompatible with series coupling of the photosystems. It is merely a simple way to account for several yield effects, some of which are commonly taken to be evidence for series coupling.

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TEMPERATURE DEPENDENCE OF DELAYED LIGHT EMISSION IN THE 6 to 340 MICROSECOND RANGE AFTER A SINGLE FLASH IN CHLOROPLASTS

Cited by 73 publications

References 69 publications

Photosynthetic light harvesting: excitons and coherence

Photosynthetic light harvesting: excitons and coherence

Redox potentials of primary electron acceptor quinone molecule (Q _A ) ⁻ and conserved energetics of photosystem II in cyanobacteria with chlorophyll a and chlorophyll d

Alternative perspective on photosynthetic yield and enhancement

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TEMPERATURE DEPENDENCE OF DELAYED LIGHT EMISSION IN THE 6 to 340 MICROSECOND RANGE AFTER A SINGLE FLASH IN CHLOROPLASTS

Cited by 73 publications

References 69 publications

Photosynthetic light harvesting: excitons and coherence

Photosynthetic light harvesting: excitons and coherence

Redox potentials of primary electron acceptor quinone molecule (Q A ) − and conserved energetics of photosystem II in cyanobacteria with chlorophyll a and chlorophyll d

Alternative perspective on photosynthetic yield and enhancement

Contact Info

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Redox potentials of primary electron acceptor quinone molecule (Q _A ) ⁻ and conserved energetics of photosystem II in cyanobacteria with chlorophyll a and chlorophyll d