Photosynthetic Energy Conversion: Hydrogen Photoproduction by Natural and Biomimetic Means

The main function of the photosynthetic process is to capture solar energy and to store it in the form of chemical fuels. Many fuel forms such as coal, oil and gas have been intensively used and are becoming limited. Hydrogen could become an important clean fuel for the future. Among different technologies for hydrogen production, oxygenic natural and artificial photosynthesis using direct photochemistry in synthetic complexes have a great potential to produce hydrogen as both use clean and cheap sources - water and solar energy. Photosynthetic organisms capture sunlight very efficiently and convert it into organic molecules. Artificial photosynthesis is one way to produce hydrogen from water using sunlight by employing biomimetic complexes. However, splitting of water into protons and oxygen is energetically demanding and chemically difficult. In oxygenic photosynthetic microorganisms water is splitted into electrons and protons during primary photosynthetic processes. The electrons and protons are redirected through the photosynthetic electron transport chain to the hydrogen-producing enzymes-hydrogenase or nitrogenase. By these enzymes, e- and H+ recombine and form gaseous hydrogen. Biohydrogen activity of hydrogenase can be very high but it is extremely sensitive to photosynthetic O2. At the moment, the efficiency of biohydrogen production is low. However, theoretical expectations suggest that the rates of photon conversion efficiency for H2 bioproduction can be high enough (> 10%). Our review examines the main pathways of H2 photoproduction using photosynthetic organisms and biomimetic photosynthetic systems and focuses on developing new technologies based on the effective principles of photosynthesis

Evaluation of new Cu(II) complexes as a novel class of inhibitors against plant carbonic anhydrase, glutathione reductase, and photosynthetic activity in photosystem II

International Conference on Photosynthesis Research for Sustainability -- JUN 19-25, 2016 -- Pushchino, RUSSIAWOS: 000405086400013PubMed ID: 28497193Increasing inefficiency of production of important agricultural plants raises one of the biggest problems in the modern world. Herbicide application is still the best method of weed management. Traditional herbicides blocking only one of the plant metabolic pathways is ineffective due to the rapid growth of herbicide-resistant weeds. The synthesis of novel compounds effectively suppressing several metabolic processes, and therefore achieving the synergism effect would serve as the alternative approach to weed problem. For this reason, recently, we synthesized a series of nine novel Cu(II) complexes and four ligands, characterized them with different analyses techniques, and carried out their primary evaluation as inhibitors of photosynthetic electron transfer in spinach thylakoids (design, synthesis, and evaluation of a series of Cu(II) based metal-organic complexes as possible inhibitors of photosynthesis, J Photochem Photobiol B, submitted). Here, we evaluated in vitro inhibitory potency of these agents against: photochemistry and carbonic anhydrase activity of photosystem II (PSII); alpha-carbonic anhydrase from bovine erythrocytes; as well as glutathione reductase from chloroplast and baker's yeast. Our results show that all Cu(II) complexes excellently inhibit glutathione reductase and PSII carbonic anhydrase activity. Some of them also decently inhibit PSII photosynthetic activity.Int Soc Photosynthesis Res, Int Assoc Hydrogen EnergyScientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [212T089]; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [16-34-50257, 17-04-01011, 17-54-560012, 17-0401289]; Molecular and Cell Biology Programs from Russian Academy of SciencesThis study has been supported by the Scientific and Technological Research Council of Turkey (TUBITAK-Project No. 212T089), by the Grants from Russian Foundation for Basic Research (Nos. 16-34-50257, 17-04-01011, 17-54-560012, 17-0401289), and by Molecular and Cell Biology Programs from Russian Academy of Sciences

Characterization of nineteen antimony(III) complexes as potent inhibitors of photosystem II, carbonic anhydrase, and glutathione reductase

WOS: 000385248300014PubMed ID: 26932934Nineteen antimony(III) complexes were obtained and examined as possible herbicides. Six of these were synthesized for the first time, and their structures were identified using elemental analyses, H-1-NMR, C-13-NMR, FTIR, LCMS, magnetic susceptibility, and conductivity measurement techniques. For the nineteen examined antimony(III) complexes their most-stable forms were determined by DFT/B3LYP/LanL2DZ calculation method. These compounds were examined for effects on photosynthetic electron transfer and carbonic anhydrase activity of photosystem II, and glutathione reductase from chloroplast as well were investigated. Our results indicated that all antimony(III) complexes inhibited glutathione reductase activity of chloroplast. A number of these also exhibited good inhibitory efficiency of the photosynthetic and carbonic anhydrase activity of Photosystem II.Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [212T089]; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR); Molecular and Cell Biology Programs from Russian Academy of SciencesThe authors thank Gorshkova D. for preliminary GR experiments. This study has been supported by the Scientific and Technological Research Council of Turkey (TUBITAK-Project no: 212T089), by the Grants from Russian Foundation for Basic Research, and by Molecular and Cell Biology Programs from Russian Academy of Sciences

Screening of novel chemical compounds as possible inhibitors of carbonic anhydrase and photosynthetic activity of photosystem II

WOS: 000340334300020PubMed ID: 24418071Thirty novel chemical compounds were designed and synthesized expecting that they would be possible inhibitors. From this number eleven were organic bases, twenty-four were their organic derivatives and fourteen were metal complexes. Screening of these chemicals by their action on photosynthetic electron transfer (PET) and carbonic anhydrase (CA) activity (CAA) of photosystem II (PSII), alpha-CA, as well as beta-CA was done. Several groups were revealed among them. Some of them are capable to suppress either one, two, three, or even all of the measured activities. As example, one of the Cu(II)-phenyl sulfonylhydrazone complexes (compound 25) suppresses CAA of alpha-CA by 88%, CAA of beta-CA by 100% inhibition; CAA of PSII by 100% and the PSII photosynthetic activity by 66.2%. The Schiff base compounds (12,15) and Cu(II)-phenyl sulfonylhydrazone complexes (25, 26) inhibited the CAA and PET of PSII significantly. The obtained data indicate that the PSII donor side is a target of the inhibitory action of these agents. Some physico- or electrochemical properties such as diffusion coefficient, number of transferred electrons, peak potential and heterogeneous standard rate constants of the compounds were determined in nonaqueous media. pKa values were also determined in nonaqueous and aqueous media. Availability in the studied group of novel chemical agents possessing different inhibitory activity allow in future to isolate the "active part" in the structure of the inhibitors responsible for different inhibitory mechanisms, as well as to determine the influence of side substituters on its inhibitory efficiency. (C) 2013 Elsevier B.V. All rights reserved.Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [108T317]; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [13-04-91372, 14-04-01549, 14-04-92690]; Molecular and Cell Biology Programs of the Russian Academy of SciencesRussian Academy of Sciences; BMBFFederal Ministry of Education & Research (BMBF) [8125]; COSTEuropean Cooperation in Science and Technology (COST) [MP1205]; German Federal Ministry of Education and Research (BMBF)Federal Ministry of Education & Research (BMBF) [RUS 11/014]This work has been supported partially by The Scientific and Technological Research Council of Turkey (TUBITAK-Project no: 108T317) to M.S.K, and by the grants from Russian Foundation for Basic Research (nos. 13-04-91372, 14-04-01549, 14-04-92690), by Molecular and Cell Biology Programs of the Russian Academy of Sciences, by BMBF (No: 8125) Bilateral Cooperation between Germany and Russia, to S.I.A. T. Friedrich and F.-J. Schmitt acknowledge COST for financial support in the framework of COST action MP1205 and the German Federal Ministry of Education and Research (BMBF, project RUS 11/014)

Reactive oxygen species: Re-evaluation of generation, monitoring and role in stress-signaling in phototrophic organisms

AbstractThis review provides an overview about recent developments and current knowledge about monitoring, generation and the functional role of reactive oxygen species (ROS) – H2O2, HO2, HO, OH−, 1O2 and O2− – in both oxidative degradation and signal transduction in photosynthetic organisms including microscopic techniques for ROS detection and controlled generation. Reaction schemes elucidating formation, decay and signaling of ROS in cyanobacteria as well as from chloroplasts to the nuclear genome in eukaryotes during exposure of oxygen-evolving photosynthetic organisms to oxidative stress are discussed that target the rapidly growing field of regulatory effects of ROS on nuclear gene expression

Biofuel production: Challenges and opportunities

It is increasing clear that biofuels can be a viable source of renewable energy in contrast to the finite nature, geopolitical instability, and deleterious global effects of fossil fuel energy. Collectively, biofuels include any energy-enriched chemicals generated directly through the biological processes or derived from the chemical conversion from biomass of prior living organisms. Predominantly, biofuels are produced from photosynthetic organisms such as photosynthetic bacteria, micro- and macro-algae and vascular land plants. The primary products of biofuel may be in a gas, liquid, or solid form. These products can be further converted by biochemical, physical, and thermochemical methods. Biofuels can be classified into two categories: primary and secondary biofuels. The primary biofuels are directly produced from burning woody or cellulosic plant material and dry animal waste. The secondary biofuels can be classified into three generations that are each indirectly generated from plant and animal material. The first generation of biofuels is ethanol derived from food crops rich in starch or biodiesel taken from waste animal fats such as cooking grease. The second generation is bioethanol derived from non-food cellulosic biomass and biodiesel taken from oil-rich plant seed such as soybean or jatropha. The third generation is the biofuels generated from cyanobacterial, microalgae and other microbes, which is the most promising approach to meet the global energy demands. In this review, we present the recent progresses including challenges and opportunities in microbial biofuels production as well as the potential applications of microalgae as a platform of biomass production. Future research endeavors in biofuel production should be placed on the search of novel biofuel production species, optimization and improvement of culture conditions, genetic engineering of biofuel-producing species, complete understanding of the biofuel production mechanisms, and effective techniques for mass cultivation of microorganisms. © 2016 Hydrogen Energy Publications LLC.1