scholarly journals Generation of Hydrogen and Oxygen from Water by Solar Energy Conversion

2021 ◽  
Vol 13 (24) ◽  
pp. 13941
Author(s):  
Yuriy Shapovalov ◽  
Rustam Tokpayev ◽  
Tamina Khavaza ◽  
Mikhail Nauryzbayev
Keyword(s):  
Water Oxidation ◽  
Environmentally Friendly ◽  
Water Decomposition ◽  
Light Phase ◽  
Gaseous Oxygen ◽  
Ps Ii ◽  
Photosystems I And Ii ◽  
Ps I ◽  
Initial Stage ◽  
Electrolysis System

Photosynthesis is considered to be one of the promising areas of cheap and environmentally friendly energy. Photosynthesis involves the process of water oxidation with the formation of molecular oxygen and hydrogen as byproducts. The aim of the present article is to review the energy (light) phase of photosynthesis based on the published X-ray studies of photosystems I and II (PS-I and PS-II). Using modern ideas about semiconductors and biological semiconductor structures, the mechanisms of H+, O2↑, e− generation from water are described. At the initial stage, PS II produces hydrogen peroxide from water as a result of the photoenzymatic reaction, which is oxidized in the active center of PS-II on the Mn4CaO5 cluster to form O2↑, H+, e−. Mn4+ is reduced to Mn2+ and then oxidized to Mn4+ with the transfer of reducing the equivalents of PS-I. The electrons formed are transported to PS-I (P 700), where the electrochemical reaction of water decomposition takes place in a two-electrode electrolysis system with the formation of gaseous oxygen and hydrogen. The proposed functioning mechanisms of PS-I and PS-II can be used in the development of environmentally friendly technologies for the production of molecular hydrogen.

scholarly journals Biochemical Characterization on Photosynthetic Activities during Dark Incubated Senescence of Wheat Primary Leaves by Gibberellic Acid

2019 ◽  
pp. 1-5
Author(s):  
G. Fareeda ◽  
S. D. S. Murthy
Keyword(s):  
Water Oxidation ◽  
Biochemical Characterization ◽  
Crop Yields ◽  
Moderate Increase ◽  
Ps Ii ◽  
Annual Crops ◽  
Ps I ◽  
Treated Leaf ◽  
Photosynthetic Activities ◽  
Ps Ii Activity

In annual crop plants like maize, rice and wheat etc. Senescence limits crop yields of annual crops like maize rice and wheat. Delayed leaf senescence is a desirable agronomic trait to improve crop yield. In this study 10 µM GA reduced the loss of wheat primary leaves under incubated dark conditions. GA reduced the loss of pigments, proteins, electron transport activities, spectral properties. The restoration of WCE activity by GA was closely associated with the restoration of PS II activity compared to that of PS I. GA treated leaf thylakoid membranes showed an increase in absorption at 680 nm moderate increase at 480 nm and 440 nm at 72 h during dark incubation. GA protected the degradation of water oxidation complex polypeptides (33, 23, 17 KDa) of PS II and slightly protected the PS I polypeptides.

Isolierung von PS II-Partikeln mit in vivo Eigenschaften aus Euglena gracilis, Stamm Z / Isolation of PS II-Particels with in vivo Characteristics from Euglena gracilis, Stamm Z

1982 ◽  
Vol 37 (3-4) ◽  
pp. 256-259 ◽  
Author(s):  
F. Schuler ◽  
P. Brandt ◽  
W. Wießner
Keyword(s):  
Euglena Gracilis ◽  
Fluorescence Emission ◽  
Improved Method ◽  
Ps Ii ◽  
Ps I ◽  
Emission And Absorption Spectra ◽  
Chlorophyll Protein ◽  
Ps Ii Activity ◽  
Photosystem Ii Particles

Abstract An improved method for isolation of (photosystem II)-particles from Euglena gracilis, strain Z was established. PS II-particles isolated by ultrasonic treatment and following differential centrifugation show fluorescence emission and absorption spectra identical with in vivo properties of Euglena gracilis. These PS II-particles have only PS II-activity and contain CP a, the typical chlorophyll-protein-complex of PS II. No contamination of PS I-components are detectable.

Photoinactivation of Photosynthetic Electron Transport under Anaerobic and Aerobic Conditions in Isolated Thylakoids of Spinach

1992 ◽  
Vol 47 (1-2) ◽  
pp. 63-68 ◽  
Author(s):  
Rekha Chaturvedi ◽  
M. Singh ◽  
P. V. Sane
Keyword(s):  
Electron Transport ◽  
Photosynthetic Electron Transport ◽  
Oxygen Evolving Complex ◽  
Reaction Centre ◽  
Ps Ii ◽  
Ps I ◽  
S2 State ◽  
The Stability ◽  
Oxygen Evolving ◽  
Spinach Thylakoids

Abstract The effect of exposure to strong white light on photosynthetic electron transport reactions of PS I and PS II were investigated in spinach thylakoids in the absence or presence of oxygen. Irrespective of the conditions used for photoinactivation, the damage to PS II was always much more than to PS I. Photoinactivation was severe under anaerobic conditions compared to that in air for the same duration. This shows that the presence of oxygen is required for prevention of photoinactivation of thylakoids. The susceptibility of water-splitting complex in photoinactivation is indicated by our data from experiments with chloride-deficient chloroplast membranes wherein it was observed that the whole chain electron transport from DPC to MV was much less photoinhibited than that from water. The data from the photoinactivation experiments with the Tris-treated thylakoids indicate another photodam age site at or near reaction centre of PS II. DCMU-protected PS II and oxygen-evolving complex from photoinactivation. DCMU protection can also be interpreted in terms of the stability of the PS II complex when it is in S2 state.

scholarly journals The chlorophyll a/b -proteins of PS I and PS II are immunologically related

FEBS Letters ◽  
1986 ◽  
Vol 199 (2) ◽  
pp. 227-233 ◽  
Author(s):  
Paula K. Evans ◽  
Jan M. Anderson
Keyword(s):  
Chlorophyll A ◽  
Ps Ii ◽  
Ps I

scholarly journals Determination of the PS I content of PS II core preparations using selective emission: A new emission of PS II at 780nm

2014 ◽  
Vol 1837 (1) ◽  
pp. 167-177 ◽  
Author(s):  
Jennifer Morton ◽  
Jeremy Hall ◽  
Paul Smith ◽  
Fusamichi Akita ◽  
Faisal Hammad Mekky Koua ◽  
...  
Keyword(s):  
Ps Ii ◽  
Ps I ◽  
Ps Ii Core

scholarly journals Proton flow through the ATP synthase in chloroplasis regulates the distribution of light energy between PS I and PS II

FEBS Letters ◽  
1991 ◽  
Vol 282 (2) ◽  
pp. 449-449
Author(s):  
G. Braun ◽  
Y. Evron ◽  
S. Malkin ◽  
M. Avron
Keyword(s):  
Atp Synthase ◽  
Light Energy ◽  
Ps Ii ◽  
Ps I ◽  
Flow Through

Is the in vivo Photosystem I Function Resistant to Photoinhibition? An Answer from Photoacoustic and Far-Red Absorbance Measurements in Intact Leaves

1991 ◽  
Vol 46 (11-12) ◽  
pp. 1038-1044 ◽  
Author(s):  
Michel Havaux ◽  
Murielle Eyletters
Keyword(s):  
Light Stress ◽  
Red Light ◽  
Light Treatment ◽  
High Light ◽  
Saturation Curve ◽  
Strong Light ◽  
Ps Ii ◽  
Fluorescence Measurements ◽  
Ps I

Abstract Preillumination of intact pea leaves with a strong blue-green light of 400 W m-2 markedly inhibited both photoacoustically monitored O2-evolution activity and PS II photochemistry as estimated from chlorophyll fluorescence measurements. The aim of the present work was to examine, with the help of the photoacoustic technique, whether this high-light treatment deteriorated the in vivo PS I function too. High-frequency photoacoustic measurements indicated that photochemical conversion of far-red light energy in PS I was preserved (and even transiently stimulated) whereas photochemical energy storage monitored in light exciting both PS I and PS II was markedly diminished. Low-frequency photoacoustic measurements of the Emerson enhancement showed a spectacular change in the PS II/PS I activity balance in favor of PS I. It was also observed that the linear portion of the saturation curve of the far-red light effect in the Emerson enhancement was not changed by the light treatment. Those results lead to the conclusion that, in contrast to PS II, the in vivo PS I photofunctioning was resistant to strong light stress, thus confirming previous suggestions derived from in vitro studies. Estimation of the redox state of the PS I reaction center by leaf absorbance measurements at ca. 820 nm suggested that, under steady illumination, a considerably larger fraction of PS I centers were in the closed state in high-light pretreated leaves as compared to control leaves, presumably allowing passive adjustment of the macroscopic quantum yield of PS I photochemis­ try to the strongly reduced photochemical efficiency of photoinhibited PS II.

Sign in / Sign up

Export Citation Format

Share Document