Charge Recombination and Proton Transfer in Manganese-Depleted Photosystem II†

Biochemistry ◽  
1997 ◽  
Vol 36 (49) ◽  
pp. 15294-15302 ◽  
Author(s):  
Fabrice Rappaport ◽  
Jérôme Lavergne
Keyword(s):  
Photosystem Ii ◽  
Proton Transfer ◽  
Charge Recombination

scholarly journals Rigidly hydrogen-bonded water molecules facilitate proton transfer in photosystem II

2020 ◽  
Vol 22 (28) ◽  
pp. 15831-15841
Author(s):  
Naoki Sakashita ◽  
Hiroshi Ishikita ◽  
Keisuke Saito
Keyword(s):  
Photosystem Ii ◽  
Proton Transfer ◽  
Water Molecules ◽  
Hydrogen Bonded

In the channel of photosystem II, rigidly hydrogen-bonded water molecules facilitate the Grotthuss-like proton transfer, whereas flexible water molecules prevent proton transfer in the channel of aquaporin.

scholarly journals Bicarbonate rescues damaged proton-transfer pathway in photosystem II

2019 ◽  
Vol 1860 (8) ◽  
pp. 611-617 ◽  
Author(s):  
Gourab Banerjee ◽  
Ipsita Ghosh ◽  
Christopher J. Kim ◽  
Richard J. Debus ◽  
Gary W. Brudvig
Keyword(s):  
Photosystem Ii ◽  
Proton Transfer

scholarly journals Electron, proton and hydrogen–atom transfers in photosynthetic water oxidation

2002 ◽  
Vol 357 (1426) ◽  
pp. 1383-1394 ◽  
Author(s):  
Cecilia Tommos
Keyword(s):  
Photosystem Ii ◽  
Proton Transfer ◽  
Water Oxidation ◽  
Oxidation Mechanism ◽  
Bulk Solution ◽  
Hydrogen Atoms ◽  
Redox Active ◽  
Hydrogen Atom Transfers ◽  
Reduce Carbon Dioxide ◽  
Photosynthetic Water Oxidation

When photosynthetic organisms developed so that they could use water as an electron source to reduce carbon dioxide, the stage was set for efficient proliferation. Algae and plants spread globally and provided the foundation for our atmosphere and for O 2 –based chemistry in biological systems. Light–driven water oxidation is catalysed by photosystem II, the active site of which contains a redox–active tyrosine denoted Y Z , a tetramanganese cluster, calcium and chloride. In 1995, Gerald Babcock and co–workers presented the hypothesis that photosynthetic water oxidation occurs as a metallo–radical catalysed process. In this model, the oxidized tyrosine radical is generated by coupled proton/electron transfer and re–reduced by abstracting hydrogen atoms from substrate water or hydroxide–ligated to the manganese cluster. The proposed function of Y Z requires proton transfer from the tyrosine site upon oxidation. The oxidation mechanism of Y Z in an inhibited and O 2 –evolving photosystem II is discussed. Domino–deprotonation from Y Z to the bulk solution is shown to be consistent with a variety of data obtained on metal–depleted samples. Experimental data that suggest that the oxidation of Y Z in O 2 –evolving samples is coupled to proton transfer in a hydrogen–bonding network are described. Finally, a dielectric–dependent model for the proton release that is associated with the catalytic cycle of photosystem II is discussed.

scholarly journals Design and synthesis of benzimidazole phenol-porphyrin dyads for the study of bioinspired photoinduced proton-coupled electron transfer

2019 ◽  
Vol 23 (11n12) ◽  
pp. 1336-1345
Author(s):  
S. Jimena Mora ◽  
Daniel A. Heredia ◽  
Emmanuel Odella ◽  
Uma Vrudhula ◽  
Devens Gust ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Photosystem Ii ◽  
Proton Transfer ◽  
Water Oxidation ◽  
Oxidation Catalyst ◽  
Design And Synthesis ◽  
Proton Coupled Electron Transfer ◽  
Anchoring Groups ◽  
High Redox Potential

Benzimidazole phenol-porphyrin dyads have been synthesized to study proton-coupled electron transfer (PCET) reactions induced by photoexcitation. High-potential porphyrins have been chosen to model P680, the photoactive chlorophyll cluster of photosynthetic photosystem II (PSII). They have either two or three pentafluorophenyl groups at the meso positions to impart the high redox potential. The benzimidazole phenol (BIP) moiety models the Tyr[Formula: see text]-His190 pair of PSII, which is a redox mediator that shuttles electrons from the water oxidation catalyst to P680[Formula: see text]. The dyads consisting of a porphyrin and an unsubstituted BIP are designed to study one-electron one-proton transfer (E1PT) processes upon excitation of the porphyrin. When the BIP moiety is substituted with proton-accepting groups such as imines, one-electron two-proton transfer (E2PT) processes are expected to take place upon oxidation of the phenol by the excited state of the porphyrin. The bis-pentafluorophenyl porphyrins linked to BIPs provide platforms for introducing a variety of electron-accepting moieties and/or anchoring groups to attach semiconductor nanoparticles to the macrocycle. The triads thus formed will serve to study the PCET process involving the BIPs when the oxidation of the phenol is achieved by the photochemically produced radical cation of the porphyrin.

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