scholarly journals Impact of D1-V185 on the Water Molecules That Facilitate O2 Formation by the Catalytic Mn4CaO5 Cluster in Photosystem II

Biochemistry ◽  
2018 ◽  
Vol 57 (29) ◽  
pp. 4299-4311 ◽  
Author(s):  
Christopher J. Kim ◽  
Han Bao ◽  
Robert L. Burnap ◽  
Richard J. Debus
Keyword(s):  
Photosystem Ii ◽  
Water Molecules

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 Energetics of Ionized Water Molecules in the H-Bond Network near the Ca2+ and Cl– Binding Sites in Photosystem II

Biochemistry ◽  
2020 ◽  
Vol 59 (35) ◽  
pp. 3216-3224 ◽  
Author(s):  
Keisuke Saito ◽  
Manoj Mandal ◽  
Hiroshi Ishikita
Keyword(s):  
Photosystem Ii ◽  
Binding Sites ◽  
Water Molecules ◽  
Bond Network

Water Molecules Coupled to the Redox-Active Tyrosine YDin Photosystem II as Detected by FTIR Spectroscopy†

Biochemistry ◽  
2007 ◽  
Vol 46 (49) ◽  
pp. 14245-14249 ◽  
Author(s):  
Ryouta Takahashi ◽  
Miwa Sugiura ◽  
Takumi Noguchi
Keyword(s):  
Photosystem Ii ◽  
Ftir Spectroscopy ◽  
Water Molecules ◽  
Redox Active

scholarly journals QM/MM computational studies of substrate water binding to the oxygen-evolving centre of photosystem II

2007 ◽  
Vol 363 (1494) ◽  
pp. 1149-1156 ◽  
Author(s):  
Eduardo M Sproviero ◽  
Katherine Shinopoulos ◽  
José A Gascón ◽  
James P McEvoy ◽  
Gary W Brudvig ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Exchange Rates ◽  
Water Exchange ◽  
Metal Cluster ◽  
Bound Water ◽  
Water Molecules ◽  
Computational Studies ◽  
Water Binding ◽  
Model Complexes ◽  
Oxygen Evolving

This paper reports computational studies of substrate water binding to the oxygen-evolving centre (OEC) of photosystem II (PSII), completely ligated by amino acid residues, water, hydroxide and chloride. The calculations are based on quantum mechanics/molecular mechanics hybrid models of the OEC of PSII, recently developed in conjunction with the X-ray crystal structure of PSII from the cyanobacterium Thermosynechococcus elongatus . The model OEC involves a cuboidal Mn 3 CaO 4 Mn metal cluster with three closely associated manganese ions linked to a single μ 4 -oxo-ligated Mn ion, often called the ‘dangling manganese’. Two water molecules bound to calcium and the dangling manganese are postulated to be substrate molecules, responsible for dioxygen formation. It is found that the energy barriers for the Mn(4)-bound water agree nicely with those of model complexes. However, the barriers for Ca-bound waters are substantially larger. Water binding is not simply correlated to the formal oxidation states of the metal centres but rather to their corresponding electrostatic potential atomic charges as modulated by charge-transfer interactions. The calculations of structural rearrangements during water exchange provide support for the experimental finding that the exchange rates with bulk 18 O-labelled water should be smaller for water molecules coordinated to calcium than for water molecules attached to the dangling manganese. The models also predict that the S 1 →S 2 transition should produce opposite effects on the two water-exchange rates.

The structure and activation of substrate water molecules in the S2 state of photosystem II studied by hyperfine sublevel correlation spectroscopy

2012 ◽  
Vol 5 (7) ◽  
pp. 7747 ◽  
Author(s):  
Sergey Milikisiyants ◽  
Ruchira Chatterjee ◽  
Christopher S. Coates ◽  
Faisal H. M. Koua ◽  
Jian-Ren Shen ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Correlation Spectroscopy ◽  
Water Molecules ◽  
Hyperfine Sublevel Correlation Spectroscopy ◽  
S2 State ◽  
Hyperfine Sublevel Correlation

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.

Structural and dynamic insights into Mn4Ca cluster-depleted Photosystem II

2021 ◽  
Author(s):  
Daniele Narzi ◽  
Leonardo Guidoni
Keyword(s):  
Photosystem Ii ◽  
Molecular Oxygen ◽  
Oxygenic Photosynthesis ◽  
Water Molecules ◽  
Sun Light

In the first steps of natural oxygenic photosynthesis, Sun light is used to oxidize water molecules into protons, electrons and molecular oxygen. This reaction takes place on the Mn$_4$Ca cluster...

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