Proton-Coupled Electron Transfer of Plastoquinone Redox Reactions in Photosystem II: A Pump–Probe Ultraviolet Resonance Raman Study

Chen, Jinfan; Liu, Ying; Zheng, Y.; Zhu, Qingjun; Han, Guangye; Shen, Jian Ren

doi:10.1021/acs.jpclett.9b00959

Cited by 4 publications

(3 citation statements)

References 60 publications

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“…Furthermore, chromium and other trace elements may cause ultrastructure abnormalities in mesophyll cells and root cells ultimately increased metal deposition in some plant parts. Several previous studies have suggested the inhibitory effect of chromium on PSII activity mostly studies have been performed on cellular membrane damaging effect, to increase knowledge about the negative effect of chromium on photosynthesis PSII activity to evaluate the toxic effect of chromium on photosynthetic apparatus (Souri et al, 2019), Chromium stress induces changes in ultrastructure of chloroplast, electron transport chain (Chen et al, 2019). At PSII chromium ions replaces the co-factor Ca 2+ known to be very important for water-splitting, hence alters the structure and function of oxygen evolving complex.…”

Section: Introductionmentioning

confidence: 99%

Differential responses of exogenous melatonin on growth, photosynthesis and antioxidant defence system in two Brassica napus L.cultivars under chromium stress

Ayyaz¹,

Farooq²,

Kanwal³

et al. 2020

IJEAB

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Rapid industrialization throughout the world during last few decades causing high chromium resulted widespread of agricultural soil contamination. The increased chromium contents beyond permissible level in some agricultural land areas increasing widespread concern about food safety.This study was carried out for evaluation of metal toxicity damage and its possible mitigation and improved photosynthetic efficiency by melatonin treatment in canola plants exposed to four melatonin levels (0,1,5,10µM) treated with chromium stress (0,50,100µM) for two days.Chlorophyll fluorescence a transients considered one of the best tool for photosynthetic (photosystem II) efficiency analysis of two canola cultivars Ac-Excel and DGL with or without melatonin treatment against chromium stress analyzed by using OJIP test (at different time scale) chromium treated and non-treated plants. Enhanced ROS scavenging antioxidants enzymes (SOD, POD, APX,CAT) and H2O2, MD Aactivity photo synthetic efficiency was observed against chromium stress. DGL cultivar showed greatly affected and showed maximum reduction in performing index of photosystem II and yield for primary photochemistry as compared to chromium treated and non-treated plants as compared to Ac-Excel. Performing index primarily comprises of active number of reaction centers as per absorption, primary photochemistry yield and efficiency of electron transfer in electron transport chain activities were observed high in Ac-Excel cultivar. However exogenous application of melatonin protected the oxygen evolving complex of PSII and helped out in maintaining PSII activity. Thus OJIP fluorescence transients are quite helpful for understanding the intersystem electron transport beyond photosystem II response of canola cultivars in chromium stress. Findings: Exogenous application of Melatonin can improve plant growth and development in heavy metalstress by modulation of photosynthesis in terms of enhanced photosystem II efficiency and redox potential in certain environmental stress conditions.

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Section: Introductionmentioning

confidence: 99%

Differential responses of exogenous melatonin on growth, photosynthesis and antioxidant defence system in two Brassica napus L.cultivars under chromium stress

Ayyaz¹,

Farooq²,

Kanwal³

et al. 2020

IJEAB

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“…It is thus reasonable to attribute the shifts in the redox potential of Q A to the structural changes that occur upon Mn/Ca depletion or Ca 2+ /Sr 2+ exchanges [5,10,11,16]. Q A is stabilized by van der Waals interactions, including two moderate H-bonds between its carbonyl oxygen (C=O1, proximal; C=O2, distal) and N-Phe261-D2 and N δ -His214-D2, respectively, as well as a π-stacking interaction with the nearby highly conserved D2-Trp253 (Table 1; Figure 3) [2,17]. This interaction is similar to the corresponding native Q A interaction with slightly higher thermal motion, i.e., a 10%–20% increase in the temperature (B) factors (Table 1).…”

Section: Resultsmentioning

confidence: 99%

Structural Changes in the Acceptor Site of Photosystem II upon Ca2+/Sr2+ Exchange in the Mn4CaO5 Cluster Site and the Possible Long-Range Interactions

Koua

2019

Biomolecules

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The Mn4CaO5 cluster site in the oxygen-evolving complex (OEC) of photosystem II (PSII) undergoes structural perturbations, such as those induced by Ca2+/Sr2+ exchanges or Ca/Mn removal. These changes have been known to induce long-range positive shifts (between +30 and +150 mV) in the redox potential of the primary quinone electron acceptor plastoquinone A (QA), which is located 40 Å from the OEC. To further investigate these effects, we reanalyzed the crystal structure of Sr-PSII resolved at 2.1 Å and compared it with the native Ca-PSII resolved at 1.9 Å. Here, we focus on the acceptor site and report the possible long-range interactions between the donor, Mn4Ca(Sr)O5 cluster, and acceptor sites.

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“…Compared with the blooming publications on the organic synthetic methodologies promoted by PCET, the professional and deep experimental studies on PCET mechanism for revealing its fundamental rules are relatively rare in China, [151,[172][173][174][175] however, we are glad to see that more publications on theoretical studies have been published from Chinese groups in last five year. [173][174][175][176][177][178][179][180] Further explorations of PCET mechanism including how substrates and reaction conditions influence and regulate the PCET pathways, and so on, may provide novel ideas and methods for current synthetic methodology, and even help chemists discover unexpected patterns of chemical bond forming and breaking. Therefore, future works are supposed to focus on not only the synthetic applications, but also mechanism studies of PCET reactions, including new forms of PCET processes, which should benefit the development of other branches of chemistry.…”

Section: Discussionmentioning

confidence: 98%

Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Zhou¹,

Kong²,

Liu³

2021

Chinese Journal of Organic Chemistry

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Proton-coupled electron transfer (PCET) reactions are a kind of unconventional redox reactions, which exhibit special reactivities and selectivities due to their unique interdependent electron-proton transfer mechanisms. There are three possible pathways of PCET processes, including stepwise electron transfer followed by proton transfer (ETPT), proton transfer followed by electron transfer (PTET), and concerted pathway in which electron and proton transfer synchronously (CEPT), avoiding intermediates with high energy. These reactions have been playing a key role in numerous areas in organic chemistry, inorganic chemistry, bioorganic chemistry, organometallic and material chemistry, including the redox processes in natural and artificial systems, such as the activation for small molecules. Recently, the application of PCET reactions in organic synthesis has received a great deal of attentions and interests. Being accompanied by the development of electrochemical methods and photocatalysts, more and more novel reactions in electrochemistry and photochemistry involve PCET processes have been reported. Applying these electrochemical and photochemical methods, the activation of X-H bond has been achieved via PCET processes, including C-H bond, N-H bond, P-H bond, S-H bond or O-H bond. Thus, based on these crucial processes, a number of vital structures and fundamental frameworks can be synthesized, and various synthetic building blocks and natural products have been attained. For example, pharmaceutical building blocks like 2°-piperidines can be cyanated at their α-position; substituted dimeric pyrroloindolines such as (-)-calycanthidine, (-)-chimonanthine, and (-)-psychotriasine have also been successfully synthesized via PCET mechanism. Moreover, not only the products of reduction of multiple bonds (C＝ Y bond such as C＝C bond, C＝N bond and C＝O bond), but also the products of self/cross-coupling have been achieved via PCET mechanism. In this review, the recent applications and developments of PCET mechanism in organic synthesis are summarized, including new catalyst systems and new reagents, especially with electrochemical and photochemical methodologies. The future of this area has also been demonstrated from both experimental and theoretical aspects. Keywords proton-coupled electron transfer; organic synthesis; radical reactions; functionalization

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Proton-Coupled Electron Transfer of Plastoquinone Redox Reactions in Photosystem II: A Pump–Probe Ultraviolet Resonance Raman Study

Cited by 4 publications

References 60 publications

Differential responses of exogenous melatonin on growth, photosynthesis and antioxidant defence system in two Brassica napus L.cultivars under chromium stress

Differential responses of exogenous melatonin on growth, photosynthesis and antioxidant defence system in two Brassica napus L.cultivars under chromium stress

Structural Changes in the Acceptor Site of Photosystem II upon Ca2+/Sr2+ Exchange in the Mn4CaO5 Cluster Site and the Possible Long-Range Interactions

Applications of Proton-Coupled Electron Transfer in Organic Synthesis

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