scholarly journals Selective nitration of PsbO1 inhibits oxygen evolution from isolated Arabidopsis thylakoid membranes

2017 ◽  
Vol 12 (4) ◽  
pp. e1304342 ◽  
Author(s):  
Misa Takahashi ◽  
Jun Shigeto ◽  
Atsushi Sakamoto ◽  
Hiromichi Morikawa
Keyword(s):  
Oxygen Evolution ◽  
Thylakoid Membranes ◽  
Selective Nitration

Photoelectron transport ability of chloroplast thylakoid membranes treated with NO donor SNP: Changes in flash oxygen evolution and chlorophyll fluorescence

Nitric Oxide ◽  
2011 ◽  
Vol 24 (2) ◽  
pp. 84-90 ◽  
Author(s):  
Radka Vladkova ◽  
Anelia G. Dobrikova ◽  
Ranjeet Singh ◽  
Amarendra N. Misra ◽  
Emilia Apostolova
Keyword(s):  
Chlorophyll Fluorescence ◽  
Oxygen Evolution ◽  
Thylakoid Membranes ◽  
No Donor

Effect of α-, β-and γ-Cyclodextrins on Oxygen Evolution by the Thylakoid Membrane. Influence of pH and Temperature

2001 ◽  
Vol 56 (9-10) ◽  
pp. 792-802 ◽  
Author(s):  
Govindachary Sridharan ◽  
Simon Gaudreau ◽  
Laetitia Dalstein ◽  
Christelle Huiban ◽  
Agnès Lejeune ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Thylakoid Membrane ◽  
Ph Dependence ◽  
Thylakoid Membranes ◽  
Red Shift ◽  
Chemical Effect ◽  
Second Derivative ◽  
Important Conclusion ◽  
Derivative Spectra ◽  
Second Derivative Spectra

AbstractThe present work investigates the effect of α-, β- and γ-cyclodextrins (CD), i.e., α-CD, β- CD and γ-CD, on the oxygen evolution activity, the protein content and the uv-vis spectroscopic characteristics of thylakoid membranes. To study the pH-dependence, the thylakoids were incubated with the cyclodextrins at 273 K for a period of 10 min in the pH range from 5.5 to 9.0. To study the temperature-dependence the membranes were incubated at 273 and 293 K at pH 6.5, that is, the pH which induces a maximal oxygen evolution in the thylakoid preparations. The major observations are: (i) a stimulation of oxygen evolution in thylakoids incubated with α- and β-CD either in acidic or alkaline conditions, (ii) a low inhibitory effect induced by γ-CD on oxygen evolution, (iii) a significant decrease of the stimulatory effect of α- and β-CD on oxygen evolution as the incubation temperature is raised from 273 to 293 K, (iv) the apparent inability of the cyclodextrins to change the protein contents of the thylakoids, and (v) a significant CD-induced red-shift from 681 to 683 nm observed in the absorption and second derivative spectra of the thylakoid membranes treated with β-CD. First, it was found that the temperature effect described here is in accord with the general trend of the chemical effect of various cyclodextrins, i.e., the increase of the CD efficiency with decreasing temperature. Secondly, the CD effect is related to the size of the inner cavity diameter of the cyclodextrin molecules. An important conclusion in this work is that the molecular targets of the cyclodextrins are not limited to the thylakoid lipids as was described previously [Rawyler A. and Siegenthaler P.A. (1996) Biochim. Biophys. Acta 1278, 89-97], but are located as well in other molecular species exposed at the stromal side of the thylakoid membrane. In particular, the CD-induced red-shift from 681 to 683 nm in the absorption and second derivative spectra of the thylakoid membranes indicates that the cyclodextrins targets might be either the exposed heme macrocycle in cytochrome b559, or the chlorophylls and pheophytins in the pigment-proteins of the photosystems I and II.

Effect of α- and β-cyclodextrins on the photochemical activity of thylakoid membranes and photosystem II particles from barley (Hordeum vulgare): oxygen evolution and whole chain electron transport

2005 ◽  
Vol 83 (3) ◽  
pp. 320-328 ◽  
Author(s):  
S Dudekula ◽  
G Sridharan ◽  
M Fragata
Keyword(s):  
Electron Transfer ◽  
Electron Transport ◽  
Hordeum Vulgare ◽  
Photosystem Ii ◽  
Oxygen Evolution ◽  
Thylakoid Membranes ◽  
Photochemical Activity ◽  
Nonlinear Dependence ◽  
Hordeum Vulgare L ◽  
Sigmoidal Curve

The effect of α- and β-cyclodextrin (CD) concentration (0–16 mM) on oxygen evolution in photosystem II (PSII) and whole chain electron transport (H2O to photosystem I (PSI)) was studied in isolated thylakoid membranes and PSII particles from barley (Hordeum vulgare L.). The CDs are cyclic oligosaccharides containing, for example, six (α-CD) or seven (β-CD) α-D-glucose residues linked by α-1,4 glycosidic bonds. These compounds alter the lipid composition of the thylakoids and most likely also the structure of their membrane proteins. We show for the first time that in the thylakoid membranes, but not in the isolated PSII particles, the relationship between oxygen evolution in PSII and the CD concentration is represented by a S-shaped (sigmoidal) curve displaying a sharp inflexion point or transition. We found, in addition, that the CDs inhibit the whole chain electron transport from H2O to methyl viologen, that is, PSI, measured as oxygen uptake, according to a nonlinear dependence that is also sigmoidal. Moreover, another interesting observation is that in the thylakoid membranes the electron transport from H2O to PSI is quite well inhibited at low CD concentrations (<4–6 mM), whereas the oxygen evolution in PSII is only substantially enhanced at CD concentrations greater than 8–10 mM. To explain this, we suggest that the mechanisms underlying the inhibition of electron transfer from H2O to PSI become operative before those giving origin to the enhancement of oxygen evolution in PSII.Key words: cyclodextrins, electron transfer, nonlinearity, oxygen evolution, photosystem, thylakoid membrane.

Rational prediction of multifunctional bilayer single atom catalysts for the hydrogen evolution, oxygen evolution and oxygen reduction reactions

Nanoscale ◽  
2020 ◽  
Vol 12 (39) ◽  
pp. 20413-20424
Author(s):  
Riming Hu ◽  
Yongcheng Li ◽  
Fuhe Wang ◽  
Jiaxiang Shang
Keyword(s):  
Oxygen Reduction ◽  
Hydrogen Evolution ◽  
Oxygen Evolution ◽  
Single Atom ◽  
Reduction Reactions ◽  
Oxygen Reduction Reactions

Bilayer single atom catalysts can serve as promising multifunctional electrocatalysts for the HER, ORR, and OER.

Towards a Design of Active Oxygen Evolution Catalysts: Insights from Automated Density Functional Theory Calculations and Machine Learning

2019 ◽  
Author(s):  
Seoin Back ◽  
Kevin Tran ◽  
Zachary Ulissi
Keyword(s):  
Machine Learning ◽  
Oxygen Evolution ◽  
Active Sites ◽  
Density Functional ◽  
Chemical Space ◽  
Density Functional Theory Calculations ◽  
Catalyst Design ◽  
Transition Metal Catalysts ◽  
Oxide Materials ◽  
Design Strategies

<div> <div> <div> <div><p>Developing active and stable oxygen evolution catalysts is a key to enabling various future energy technologies and the state-of-the-art catalyst is Ir-containing oxide materials. Understanding oxygen chemistry on oxide materials is significantly more complicated than studying transition metal catalysts for two reasons: the most stable surface coverage under reaction conditions is extremely important but difficult to understand without many detailed calculations, and there are many possible active sites and configurations on O* or OH* covered surfaces. We have developed an automated and high-throughput approach to solve this problem and predict OER overpotentials for arbitrary oxide surfaces. We demonstrate this for a number of previously-unstudied IrO2 and IrO3 polymorphs and their facets. We discovered that low index surfaces of IrO2 other than rutile (110) are more active than the most stable rutile (110), and we identified promising active sites of IrO2 and IrO3 that outperform rutile (110) by 0.2 V in theoretical overpotential. Based on findings from DFT calculations, we pro- vide catalyst design strategies to improve catalytic activity of Ir based catalysts and demonstrate a machine learning model capable of predicting surface coverages and site activity. This work highlights the importance of investigating unexplored chemical space to design promising catalysts.<br></p></div></div></div></div><div><div><div> </div> </div> </div>

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