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

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.

The structure and activation of substrate water molecules in Sr2+-substituted photosystem II

2014 ◽  
Vol 16 (38) ◽  
pp. 20834-20843 ◽  
Author(s):  
Ruchira Chatterjee ◽  
Sergey Milikisiyants ◽  
Christopher S. Coates ◽  
Faisal H. M. Koua ◽  
Jian-Ren Shen ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Photosystem Ii ◽  
Epr Spectroscopy ◽  
Direct Evidence ◽  
Water Molecules ◽  
Hydrogen Bond Network ◽  
Spectroscopy Study ◽  
Structural Role ◽  
Bond Network

An EPR spectroscopy study with direct evidence that the Ca2+ ion plays a structural role in maintaining the hydrogen-bond network in photosystem II.

scholarly journals Molecular dynamics approach for capturing calixarenes--proteins interactions: the case of cytochrome c

2020 ◽  
Author(s):  
Alessio Bartocci ◽  
florence szczepaniak ◽  
Tao Jiang ◽  
Natacha Gillet ◽  
Elise Dumont
Keyword(s):  
Molecular Dynamics ◽  
Cytochrome C ◽  
Binding Sites ◽  
Supervised Machine Learning ◽  
Titration Calorimetry ◽  
X Ray ◽  
Poisson Boltzmann ◽  
Bond Network ◽  
Proteins Interactions ◽  
Detailed Picture

Here, we propose a molecular dynamics investigation of the supramolecular association of sulfonatedcalix-[8]-arenes to cytochrome c. The binding sites prone to interactions with sulfonated calixarenescan be identified without prior knowledge of the X-ray structure, and the binding free energiesestimated by molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) post-analysis arefound to be in neat agreement with the isothermal titration calorimetry (ITC) measurements The per-residuedecomposition reveals the detailed picture of this electrostatically-driven association and notably therole of the arginine R13 as a bridge residue between the two main anchoring sites. In addition,the analysis of the residue behavior by means of a supervised machine learning protocol unveils the formation of an hydrogen bond network far from the binding sites, increasing the rigidity of theprotein.

(NH4)[B3PO6(OH)3]·0.5H2O

2007 ◽  
Vol 63 (11) ◽  
pp. i185-i185 ◽  
Author(s):  
Wei Liu ◽  
Jingtai Zhao
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Water Molecules ◽  
Hydrogen Bond Network ◽  
Ammonium Ions ◽  
One Dimensional ◽  
Bond Network ◽  
Solvothermal Conditions

The title compound, ammonium catena-[monoboro-monodihydrogendiborate-monohydrogenphosphate] hemihydrate, was obtained under solvothermal conditions using glycol as the solvent. The crystal structure is constructed of one-dimensional infinite borophosphate chains, which are interconnected by ammonium ions and water molecules via a complex hydrogen-bond network to form a three-dimensional structure. The water molecules of crystallization are disordered over inversion centres, and their H atoms were not located.

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.

A Contact Site between the Two Reaction Center Polypeptides of Photosystem II Is Involved in Photoinhibition

1991 ◽  
Vol 46 (7-8) ◽  
pp. 557-562 ◽  
Author(s):  
A. Trebst
Keyword(s):  
Amino Acid ◽  
Photosystem Ii ◽  
Reaction Center ◽  
Binding Sites ◽  
Cleavage Site ◽  
Amino Acid Sequences ◽  
Contact Site ◽  
Quinone Binding ◽  
Herbicide Binding ◽  
Sensitive Site

Abstract A new contact site between the two reaction center polypeptides D 1 and D 2 of photosystem II close to arg 238 and arg 234 respectively is proposed. The amino acid sequences involved are between the 4 th transmembrane and a connecting parallel helix. The sequence includes a tryp­ sin sensitive site in both polypeptides, the likely cleavage site in the rapid turnover of the D 1 polypeptide and part of the herbicide binding site. The contact site is oriented towards both quinone binding sites Q A and Q B. A folding of the backbone of the amino acid sequences involved is proposed.

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
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