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 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 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.

Characterization of bonding interactions of the intermediary electron acceptor in the reaction center of Photosystem II by FTIR spectroscopy

1990 ◽  
Vol 1016 (1) ◽  
pp. 49-54 ◽  
Author(s):  
E. Nabedryk ◽  
S. Andrianambinintsoa ◽  
G. Berger ◽  
M. Leonhard ◽  
W. Mäntele ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Ftir Spectroscopy ◽  
Reaction Center ◽  
Electron Acceptor

Evaluation of solid state of rice flours produced by different milling processes using ATR-FTIR spectroscopy

2021 ◽  
Author(s):  
Daitaro Ishikawa ◽  
Jiamin Yang ◽  
Chiaki Ichikawa ◽  
Tomoyuki Fujii
Keyword(s):  
Solid State ◽  
Ir Spectra ◽  
Ftir Spectroscopy ◽  
Water Activity ◽  
Rice Flour ◽  
Milling Process ◽  
Adsorption Properties ◽  
Water Molecules ◽  
Rice Flours ◽  
Changes Of State

ABSTRACT This study evaluated the influence of the milling process on solid state of rice flours according to water activity using ATR-FTIR. A band at 1740 cm−1 attributed to the C=O stretching of lipids was detected for crystalline samples, and it disappeared at a high aw range. The CH band at 2930 cm−1 of crystalline samples gradually shifted to a higher wavenumber with aw. This band of the α-formed and wet-milled samples shifted to higher wavenumbers above 0.8aw. A band due to OH stretching mode in the 3500-3000 cm−1 region did not shift with aw. The result obtained from IR spectra suggests that the parameter K calculated by Guggenheim–Anderson–de Boar model reflected not only the interaction between water molecules but also the changes of state in solids. Consequently, the results from this study provide insights about the adsorption properties of nonideal solids such as rice flour.

Environment and Function of the Redox Active Tyrosines of Photosystem II

1995 ◽  
pp. 1207-1212 ◽  
Author(s):  
Bruce A. Diner ◽  
Xiao-Song Tang ◽  
Ming Zheng ◽  
G. Charles Dismukes ◽  
Dee Ann Force ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Redox Active ◽  
And Function
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