scholarly journals Microsolvation of the Redox-Active Tyrosine-D in Photosystem II: Correlation of Energetics with EPR Spectroscopy and Oxidation-Induced Proton Transfer

2019 ◽  
Vol 141 (7) ◽  
pp. 3217-3231 ◽  
Author(s):  
Abhishek Sirohiwal ◽  
Frank Neese ◽  
Dimitrios A. Pantazis
Keyword(s):  
Photosystem Ii ◽  
Proton Transfer ◽  
Epr Spectroscopy ◽  
Redox Active ◽  
Tyrosine D

scholarly journals Energetics of the Proton Transfer Pathway for Tyrosine D in Photosystem II

2016 ◽  
Vol 69 (9) ◽  
pp. 991 ◽  
Author(s):  
Keisuke Saito ◽  
Naoki Sakashita ◽  
Hiroshi Ishikita
Keyword(s):  
Hydrogen Bond ◽  
Photosystem Ii ◽  
Proton Transfer ◽  
Electrostatic Interactions ◽  
Water Molecules ◽  
Hydrogen Bond Network ◽  
Redox States ◽  
Redox Active ◽  
Bond Network ◽  
Tyrosine D

The proton transfer pathway for redox active tyrosine D (TyrD) in photosystem II is a hydrogen-bond network that involves D2-Arg180 and a series of water molecules. Using quantum mechanical/molecular mechanical calculations, the detailed properties of the energetics and structural geometries were investigated. The potential-energy profile of all hydrogen bonds along the proton transfer pathway indicates that the overall proton transfer from TyrD is energetically downhill. D2-Arg180 plays a key role in the proton transfer pathway, providing a driving force for proton transfer, maintaining the hydrogen-bond network structure, stabilising P680•+, and thus deprotonating TyrD-OH to TyrD-O•. A hydrophobic environment near TyrD enhances the electrostatic interactions between TyrD and redox active groups, e.g. P680 and the catalytic Mn4CaO5 cluster: the redox states of those groups are linked with the protonation state of TyrD, i.e. release of the proton from TyrD. Thus, the proton transfer pathway from TyrD may ultimately contribute to the conversion of S0 into S1 in the dark in order to stabilise the Mn4CaO5 cluster when the photocycle is interrupted in S0.

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 High-resolution cryo-EM structure of photosystem II reveals damage from high-dose electron beams

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Koji Kato ◽  
Naoyuki Miyazaki ◽  
Tasuku Hamaguchi ◽  
Yoshiki Nakajima ◽  
Fusamichi Akita ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Physiological State ◽  
High Dose ◽  
Final State ◽  
X Ray ◽  
Redox States ◽  
X Ray Crystallography ◽  
Cryo Electron Microscopy ◽  
Redox Active ◽  
Beam Damage

AbstractPhotosystem II (PSII) plays a key role in water-splitting and oxygen evolution. X-ray crystallography has revealed its atomic structure and some intermediate structures. However, these structures are in the crystalline state and its final state structure has not been solved. Here we analyzed the structure of PSII in solution at 1.95 Å resolution by single-particle cryo-electron microscopy (cryo-EM). The structure obtained is similar to the crystal structure, but a PsbY subunit was visible in the cryo-EM structure, indicating that it represents its physiological state more closely. Electron beam damage was observed at a high-dose in the regions that were easily affected by redox states, and reducing the beam dosage by reducing frames from 50 to 2 yielded a similar resolution but reduced the damage remarkably. This study will serve as a good indicator for determining damage-free cryo-EM structures of not only PSII but also all biological samples, especially redox-active metalloproteins.

Proton-Coupled Electron Transfer and Tyrosine D of Photosystem II

2007 ◽  
Vol 111 (43) ◽  
pp. 12599-12604 ◽  
Author(s):  
David L. Jenson ◽  
Amaris Evans ◽  
Bridgette A. Barry
Keyword(s):  
Electron Transfer ◽  
Photosystem Ii ◽  
Proton Coupled Electron Transfer ◽  
Tyrosine D

scholarly journals Photosystem II single crystals studied by EPR spectroscopy at 94 GHz: The tyrosine radical YFormula

2001 ◽  
Vol 98 (12) ◽  
pp. 6623-6628 ◽  
Author(s):  
W. Hofbauer ◽  
A. Zouni ◽  
R. Bittl ◽  
J. Kern ◽  
P. Orth ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Single Crystals ◽  
Epr Spectroscopy ◽  
Tyrosine Radical
Sign in / Sign up

Export Citation Format

Share Document