Energy Trapping and Equilibration: A Balance of Regulation and Efficiency

Barter, Laura M. C.; Klug, David R.; Grondelle, Rienk van

doi:10.1007/1-4020-4254-x_23

Cited by 10 publications

(5 citation statements)

References 175 publications

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“…(oxidized P 680 ) in some tens of ns and is in turn reduced by an electron extracted from the Mn cluster of the water splitting enzyme (transition from S 1 to S 2 ) (Diner and Britt 2005;Hillier and Messinger 2005). On the acceptor side, the electron is transferred to the pheophytin (the primary electron acceptor) within a few picoseconds (see Barter et al 2005;Renger and Holzwarth 2005 for reviews), then to the primary quinone acceptor Q A within a few hundred picoseconds. The semiquinone Q A -is in turn re-oxidized by the secondary quinone Q B .…”

Section: Real Photosynthetic Reaction Centers Versus the Simple Randamentioning

confidence: 98%

Thermoluminescence: theory

Rappaport

Lavergne

2009

Photosynth Res

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Thermoluminescence (TL) probes the emission of luminescence associated with the de-trapping of a radical pair as the temperature is increased. This technique has proved useful for characterizing the energetic arrangement of cofactors in photosynthetic reaction centers. In the original TL theory, stemming from solid-state physics, the radical pair recombination was considered to coincide with the light-emitting process. In photosynthetic systems, however, recombination takes place through various routes among which the radiative pathway generally represents a relatively minor leak, and the theoretical framework must be modified accordingly. The radiative route is the one with the largest activation energy and is thus (still) more disfavored at low temperature, so that during the heating process, the TL peak tends to lag behind the decay of the radical pair. A consequence is that the integrated luminescence emission increases with the heating rate. In this article, we examine how the characteristics of the TL emission depend on the redox potentials of the cofactors, showing good agreement between theory and experimental studies on Photosystem (PS) II mutants. We also analyze the effect on (thermo-) luminescence of the connectivity of the light-harvesting pigment antenna, and show that while this should affect significantly luminescence kinetics at room temperature, the effect on TL is expected to be small.

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Section: Real Photosynthetic Reaction Centers Versus the Simple Randamentioning

confidence: 98%

Thermoluminescence: theory

Rappaport

Lavergne

2009

Photosynth Res

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“…In oxygenic photosynthetic organisms (cyanobacteria, algae and higher plants), the light energy absorbed by chlorophylls (Chls) and accessory pigments such as carotenoids and phycobilins is transferred to the reaction centre, where the excitation energy is converted to the chemical energy (Amerongen & Dekker 2003; Larkum 2003; Renger & Holzwart 2005; Renger 2008). To maintain the efficient and rapid energy transfer, Chls and accessory pigments are bound to the integral transmembrane proteins at the proper distance and orientation (Barter, Klug & van Grondelle 2005). In higher plants, the most abundant pigment‐protein complex is light‐harvesting complex (LHC) of photosystem II (PSII) (Kühlbrandt, Wang & Fujiyoshi 1994; Liu et al .…”

Section: Introductionmentioning

confidence: 99%

Small CAB‐like proteins prevent formation of singlet oxygen in the damaged photosystem II complex of the cyanobacterium Synechocystis sp. PCC 6803

Sinha

Komenda

Knoppová

et al. 2011

Plant Cell & Environment

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The cyanobacterial small CAB-like proteins (SCPs) are single-helix membrane proteins mostly associated with the photosystem II (PSII) complex that accumulate under stress conditions. Their function is still ambiguous although they are assumed to regulate chlorophyll (Chl) biosynthesis and/or to protect PSII against oxidative damage. In this study, the effect of SCPs on the PSII-specific light-induced damage and generation of singlet oxygen ( 1 O2) was assessed in the strains of the cyanobacterium Synechocystis sp. PCC 6803 lacking PSI (PSI-less strain) or lacking PSI together with all SCPs (PSI-less/scpABCDE -strain). The lightinduced oxidative modifications of the PSII D1 protein reflected by a mobility shift of the D1 protein and by generation of a D1-cytochrome b-559 adduct were more pronounced in the PSI-less/scpABCDE -strain. This increased protein oxidation correlated with a faster formation of 1 O2 as detected by the green fluorescence of Singlet Oxygen Sensor Green assessed by a laser confocal scanning microscopy and by electron paramagnetic resonance spin-trapping technique using 2, 2, 6, 6-tetramethyl-4-piperidone (TEMPD) as a spin trap. In contrast, the formation of hydroxyl radicals was similar in both strains. Our results show that SCPs prevent 1 O2 formation during PSII damage, most probably by the binding of free Chl released from the damaged PSII complexes.

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“…The overall quantum efficiency of the charge separation process depends on the rates of many processes: excitation energy transfer from the antenna to the reaction center, charge separation and its reversal in the reaction center, charge stabilization by electron transfer to Q A , and nonphotochemical dissipation of the excited states including fluorescence, intersystem crossing, and internal conversion; see (Renger and Holzwarth 2005;Barter and Klug 2005;Bruce and Vasil'ev 2006;van Grondelle and Gobets 2006) for recent reviews. Which of these processes determine the overall rate of charge separation in PSII with open reactions centers is one of the key questions.…”

Section: Modeling Of Excitation Transfer and Trapping In Isolated Reamentioning

confidence: 99%

Toward understanding molecular mechanisms of light harvesting and charge separation in photosystem II

Vassiliev

Bruce

2008

Photosynth Res

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Conversion of light energy in photosynthesis is extremely fast and efficient, and understanding the nature of this complex photophysical process is challenging. This review describes current progress in understanding molecular mechanisms of light harvesting and charge separation in photosystem II (PSII). Breakthroughs in X-ray crystallography have allowed the development and testing of more detailed kinetic models than have previously been possible. However, due to the complexity of the light conversion processes, satisfactory descriptions remain elusive. Recent advances point out the importance of variations in the photochemical properties of PSII in situ in different thylakoid membrane regions as well as the advantages of combining sophisticated time-resolved spectroscopic experiments with atomic level computational modeling which includes the effects of molecular dynamics.

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Energy Trapping and Equilibration: A Balance of Regulation and Efficiency

Cited by 10 publications

References 175 publications

Thermoluminescence: theory

Thermoluminescence: theory

Small CAB‐like proteins prevent formation of singlet oxygen in the damaged photosystem II complex of the cyanobacterium Synechocystis sp. PCC 6803

Toward understanding molecular mechanisms of light harvesting and charge separation in photosystem II

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