Recent advances in the electrochemistry and spectroelectrochemistry of membrane proteins

Melin, Frédéric; Hellwig, Petra

doi:10.1515/hsz-2012-0344

Cited by 31 publications

(27 citation statements)

References 124 publications

(154 reference statements)

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“…Spectroelectrochemistry has been used to accurately measure the E m values of cofactors in various redox proteins (47,48) including redox cofactors in PSII (24,25,49,50). FTIR spectroelectrochemistry, which has the additional merit of being able to provide structural information, has also been used to investigate redox reactions of biomolecules and proteins (48,(50)(51)(52)(53)(54). This method was recently applied to the nonheme iron center of PSII to examine the effect of Mn depletion on the E m value and obtain structural information around the nonheme iron (50).…”

Section: Significancementioning

confidence: 99%

Redox potential of the terminal quinone electron acceptor Q_Bin photosystem II reveals the mechanism of electron transfer regulation

Kato

Nagao

Noguchi

2015

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

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Photosystem II (PSII) extracts electrons from water at a Mn 4 CaO 5 cluster using light energy and then transfers them to two plastoquinones, the primary quinone electron acceptor Q A and the secondary quinone electron acceptor Q B . This forward electron transfer is an essential process in light energy conversion. Meanwhile, backward electron transfer is also significant in photoprotection of PSII proteins. Modulation of the redox potential (E m ) gap of Q A and Q B mainly regulates the forward and backward electron transfers in PSII. However, the full scheme of electron transfer regulation remains unresolved due to the unknown E m value of Q B . Here, for the first time (to our knowledge), the E m value of Q B reduction was measured directly using spectroelectrochemistry in combination with light-induced Fourier transform infrared difference spectroscopy. The E m (Q B − /Q B ) was determined to be approximately +90 mV and was virtually unaffected by depletion of the In oxygenic photosynthesis in plants and cyanobacteria, photosystem II (PSII) has an important function in light-driven water oxidation, a process that leads to the generation of electrons and protons for CO 2 reduction and ATP synthesis, respectively (1-3). Photosynthetic water oxidation also produces molecular oxygen as a byproduct, which is the source of atmospheric oxygen and sustains virtually all life on Earth. PSII reactions are initiated by light-induced charge separation between a chlorophyll (Chl) dimer (P680) and a pheophytin (Pheo) electron acceptor, leading to the formation of a P680 + Pheo− radical pair (4, 5). An electron hole on P680+ is transferred to a Mn 4 CaO 5 cluster, the catalytic center of water oxidation, via the redox-active tyrosine, Y Z (D1-Tyr161). At the Mn 4 CaO 5 cluster, water oxidation proceeds through a cycle of five intermediates denoted S n states (n = 0-4) (6, 7). On the electron acceptor side, the electron is transferred from Pheo − to the primary quinone electron acceptor Q A and then to the secondary quinone electron acceptor Q B (8, 9). Q A and Q B have many similarities: they consist of plastoquinone (PQ), are located symmetrically around a nonheme iron center, and interact with D2 and D1 proteins, respectively, in a similar manner (Fig. 1) (10, 11). However, they play significantly different roles in PSII (8, 9). Q A is only singly reduced to transfer an electron to Q B , whereas Q B accepts one or two electrons. When Q B is doubly reduced, the resultant Q B 2− takes up two protons to form plastoquinol (PQH 2 ), which is then released into thylakoid membranes. Differences between Q A and Q B could be caused by differences in the molecular interactions of PQ with surrounding proteins in Q A and Q B pockets, although the detailed mechanism remains to be clarified (12, 13).Electron transfer reactions in PSII are highly regulated by the spatial localization of redox components and their redox potentials (E m values). Both forward and backward electron transfers are important; backward electron transfers cont...

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Section: Significancementioning

confidence: 99%

Redox potential of the terminal quinone electron acceptor Q_Bin photosystem II reveals the mechanism of electron transfer regulation

Kato

Nagao

Noguchi

2015

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

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“…The most sophisticated electroanalysis cells combine the electrochemical analysis capability with in situ spectroscopy. Spectroelectrochemistry has provided powerful techniques in the field of protein bioelectrochemistry 124,125 and has started to be implemented by different research groups for the analysis of G. sulfurreducens and Shewanella sp. bioanodes, as reviewed recently.…”

Section: Spectroelectrochemistrymentioning

confidence: 99%

Electroanalysis of microbial anodes for bioelectrochemical systems: basics, progress and perspectives

Rimboud

Pocaznoi

Erable

et al. 2014

Phys. Chem. Chem. Phys.

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Over about the last ten years, microbial anodes have been the subject of a huge number of fundamental studies dealing with an increasing variety of possible application domains. Out of several thousands of studies, only a minority have used 3-electrode set-ups to ensure well-controlled electroanalysis conditions. The present article reviews these electroanalytical studies with the admitted objective of promoting this type of investigation. A first recall of basics emphasises the advantages of the 3-electrode set-up compared to microbial fuel cell devices if analytical objectives are pursued. Experimental precautions specifically relating to microbial anodes are then noted and the existing experimental set-ups and procedures are reviewed. The state-of-the-art is described through three aspects: the effect of the polarisation potential on the characteristics of microbial anodes, the electroanalytical techniques, and the electrode. We hope that the final outlook will encourage researchers working with microbial anodes to strengthen their engagement along the multiple exciting paths of electroanalysis.

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“…[1][2][3][4] In particular, spectroelectrochemistry has contributed to a better understanding of redox active proteins. The sample cell described here (Figure 1) allows to extend the range of applications of spectroelectrochemistry to femtosecond 2D-IR spectroscopy, which is a powerful approach to investigate structure and dynamics on an ultrafast time scale.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, redox cycling and averaging of the resulting difference spectra, which can be done with the presented cell, become essential in order to cancel the effects of long time drifts of the laser and spectroscopy setup and obtain reliably the redox induced spectral differences, similar to what is done in FTIR spectroscopy of proteins, where several to sometimes hundreds of redox cycles are used. 2,17,18 Besides, redox-controlled experiments allow changing the applied potential to tune redox equilibria between different redox states.…”

Section: Introductionmentioning

confidence: 99%

A spectroelectrochemical cell for ultrafast two-dimensional infrared spectroscopy

Khoury

Wilderen

Vogt

et al. 2015

Review of Scientific Instruments

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A spectroelectrochemical cell has been designed to combine electrochemistry and ultrafast two-dimensional infrared (2D-IR) spectroscopy, which is a powerful tool to extract structure and dynamics information on the femtosecond to picosecond time scale. Our design is based on a gold mirror with the dual role of performing electrochemistry and reflecting IR light. To provide the high optical surface quality required for laser spectroscopy, the gold surface is made by electron beam evaporation on a glass substrate. Electrochemical cycling facilitates in situ collection of ultrafast dynamics of redox-active molecules by means of 2D-IR. The IR beams are operated in reflection mode so that they travel twice through the sample, i.e., the signal size is doubled. This methodology is optimal for small sample volumes and successfully tested with the ferricyanide/ferrocyanide redox system of which the corresponding electrochemically induced 2D-IR difference spectrum is reported.

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Recent advances in the electrochemistry and spectroelectrochemistry of membrane proteins

Cited by 31 publications

References 124 publications

Redox potential of the terminal quinone electron acceptor Q_Bin photosystem II reveals the mechanism of electron transfer regulation

Redox potential of the terminal quinone electron acceptor Q_Bin photosystem II reveals the mechanism of electron transfer regulation

Electroanalysis of microbial anodes for bioelectrochemical systems: basics, progress and perspectives

A spectroelectrochemical cell for ultrafast two-dimensional infrared spectroscopy

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Recent advances in the electrochemistry and spectroelectrochemistry of membrane proteins

Cited by 31 publications

References 124 publications

Redox potential of the terminal quinone electron acceptor QBin photosystem II reveals the mechanism of electron transfer regulation

Redox potential of the terminal quinone electron acceptor QBin photosystem II reveals the mechanism of electron transfer regulation

Electroanalysis of microbial anodes for bioelectrochemical systems: basics, progress and perspectives

A spectroelectrochemical cell for ultrafast two-dimensional infrared spectroscopy

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Product

Resources

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Redox potential of the terminal quinone electron acceptor Q_Bin photosystem II reveals the mechanism of electron transfer regulation

Redox potential of the terminal quinone electron acceptor Q_Bin photosystem II reveals the mechanism of electron transfer regulation