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1. Elucidation of the primary events in photosynthesis. Novel Insights based on enolisation and iminium Involvement with pheophytin in photosystem 2

Creator:
Kovacic, P.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll, electron transfer, electrostatics, and enigma elucidation
Language:
Multiple languages
Description:
Pheophytin (Pheo) is structurally constituted as to make possible certain reactions, previously given very little attention, which appear to play crucial roles in the initial electron transfer (ET) processes. The transformations involve enolisation with subsequent formation of mono- and di-iminium cations at the Pheo core. The important impact of these ions on ET from chlorophyll (Chl) to Pheo and then to quinone are evaluated. These insights rationalise the long-standing enigmas of fast transfer, across gap ET, activation-less aspect, and essential lack of reversibility. Comparisons are made to other important areas of iminium involvement, e.g. chemistry of vision, polyaniline doping, and DNA alkylation.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Ferredoxin: the central hub connecting photosystem I to cellular metabolism

Creator:
Mondal, J. and Bruce, B. D.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
přenos elektronů, electron transfer, cellular metabolism, ferredoxin, global interaction, oxidation-reduction, 2, and 581
Language:
Multiple languages
Description:
Ferredoxin (Fd) is a small soluble iron-sulfur protein essential in almost all oxygenic photosynthetic organisms. It contains a single [2Fe-2S] cluster coordinated by four cysteine ligands. It accepts electrons from the stromal surface of PSI and facilitates transfer to a myriad of acceptors involved in diverse metabolic processes, including generation of NADPH via Fd-NADP-reductase, cyclic electron transport for ATP synthesis, nitrate reduction, nitrite reductase, sulfite reduction, hydrogenase and other reductive reactions. Fd serves as the central hub for these diverse cellular reactions and is integral to complex cellular metabolic networks. We describe advances on the central role of Fd and its evolutionary role from cyanobacteria to algae/plants. We compare structural diversity of Fd partners to understand this orchestrating role and shed light on how Fd dynamically partitions between competing partner proteins to enable the optimum transfer of PSI-derived electrons to support cell growth and metabolism., J. Mondal, B. D. Bruce., and Obsahuje bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Fluorescence induction of photosynthetic bacteria

Creator:
Sipka, G., Kis, M., Smart, J. L., and Maróti, P.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
přenos elektronů, electron transfer, bacterial photosynthesis, fluorescence transients, intact cells, 2, and 581
Language:
Multiple languages
Description:
The kinetics of bacteriochlorophyll fluorescence in intact cells of the purple nonsulfur bacterium Rhodobacter sphaeroides were measured under continuous and pulsed actinic laser diode (808 nm wavelength and maximum 2 W light power) illumination on the micro- and millisecond timescale. The fluorescence induction curve was interpreted in terms of a combination of photochemical and triplet fluorescence quenchers and was demonstrated to be a reflection of redox changes and electron carrier dynamics. By adjustment of the conditions of single and multiple turnovers of the reaction center, we obtained 11 ms-1 and 120 μs-1 for the rate constants of cytochrome c23+ detachment and cyclic electron flow, respectively. The effects of cytochrome c2 deletion and chemical treatments of the bacteria and the advantages of the fluorescence induction study on the operation of the electron transport chain in vivo were discussed., G. Sipka, M. Kis, J. L. Smart, P. Maróti., and Obsahuje bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4. Photosystem II in bio-photovoltaic devices

Creator:
Voloshin, R. A., Shumilova, S. M., Zadneprovskaya, E. V., Zharmukhamedov, S. K., Alwasel, S., Hou, H. J. M., and Allakhverdiev, S. I.
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
electron transfer, photoanode, photo-bioelectrochemical cell, and photocurrent
Language:
Multiple languages
Description:
Hybrid photoelectrodes containing biological pigment-protein complexes can be used for environmentally friendly solar energy conversion, herbicide detection, and other applications. The total number of scientific publications on hybrid bio-based devices has grown rapidly over the past decades. Particular attention is paid to the integration of the complexes of PSII into photoelectrochemical devices. A notable feature of these complexes from a practical point of view is their ability to obtain electrons from abundant water. The utilization or imitation of the PSII functionality seems promising for all of the following: generating photoelectricity, photo-producing hydrogen, and detecting herbicides. This review summarizes recent advances in the development of hybrid devices based on PSII. In a brief historical review, we also highlighted the use of quinone-type bacterial reaction centers in hybrid devices. These proteins are the first from which the photoelectricity signal was detected. The photocurrent in these first systems, developed in the 70s-80s, was about 1 nA cm-2. In the latest work, by Güzel et al. (2020), a stable current of about 888 μA cm-2 as achieved in a PSII-based solar cell. The present review is inspired by this impressive progress. The advantages, disadvantages, and future endeavors of PSII-inspired bio-photovoltaic devices are also presented.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public