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Photosynthetically produced hydrogen
Osipenko, Elena ; Němcová, Yvonne (advisor) ; Ráček, Jan (referee)
Bio-hydrogen from microalgae and cyanobacteria has attracted commercial awareness due to its potential as an alternative, reliable and renewable energy source. Photosynthetic hydrogen production from algae and cyanobacteria can be interesting and promising options for clean energy, because hydrogen is produced at ambient temperature and pressure and releases only water as a by-product. The energy of sunlight is used to split the water molecule into protons (H+), electrons (e-) and O2. The protons and electrons are then recombined with the help of the enzymes hydrogenase or nitrogenase (in the case of cyanobacteria) to form H2. Both of these enzymes are sensitive to O2 and therefore require the processes of H2 formation and CO2 fixation to be separated. This bachelor's thesis aims to describe the principle of H2 formation in different cyanobacterial and algal systems and mention the problems and limitations. The thesis also presents recent approaches, including genetic and metabolic engineering of cyanobacteria and algae or co-culturing of algae and bacteria, where an anaerobic environment is created by enhanced bacterial respiration.
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Mitochondrion of Trimastix pyriformis
Novák, Lukáš ; Hampl, Vladimír (advisor) ; Kolísko, Martin (referee)
2013 DIPLOMOVÁ PRÁCE Lukáš Novák Abstract Free-living microaerophilic protist Trimastix pyriformis is closely related to oxymonads which are the largest eukaryotic group without any known mitochondrion. In contrast to oxymonads, an enigmatic reduced mitochondrion has been found in the cell of T. pyriformis. In EST data of T. pyriformis, a number of genes has been identified whose products are putatively localized in the mitochondrion. Among these are genes for all the components of the glycine cleavage system, [FeFe]hydrogenases and the mitochondrial marker Cpn60. We performed experiments in order to determine the cellular localization of these proteins. Our results show that the glycine cleavage system is localized in the mitochondrion. Results of the experiments carried out in order to localize two hydrogenases suggest also the mitochondrial localization but are not fully convincing. The attempt to localize Cpn60 has failed. We have also identified a set of new genes in transcripts of T. pyriformis and Monocercomonoides sp. (Oxymonadida). These genes code for some components of the SUF system of FeS cluster synthesis and a peroxidase rubrerythrin. Key words: Trimastix, Monocercomonoides, mitochondrion, hydrogenosome, mitosome, hydrogenase, glycine cleavage system, SUF system.
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Cytosolic hydrogenase in Trichomonas vaginalis
Dohnálková, Alena ; Hrdý, Ivan (advisor) ; Kalous, Martin (referee)
Trichomonas vaginalis is a flagellated microaerophilic protozoan from the group Excavata that cause trichomoniasis, the most common nonviral sexually transmitted disease in the world. This thesis deals with the study of hydrogenases, enzymes catalyzing reversible conversion of protons and electrons to molecular hydrogen. In T. vaginalis, hydrogenases have been identified so far only in hydrogenosomes, modified anaerobic mitochondia that are involved in energy metabolism. We proved the presence of this enzyme also in the cytosol of T. vaginalis. Among several hydrogenase paralogues present in the genome, we selected an appropriate gene for the putative cytosolic hydrogenase (C-Hyd) and verified its cytosolic localization in the cells with overexpressed C-Hyd protein. Based on the determination of hydrogenase activities in different cell compartments and fractions obtained by affinity chromatography, we demonstrated the hydrogenase activity of C-Hyd protein, which means that C-Hyd is a functional hydrogenase. Identification of hydrogenase in T. vaginalis cytosol changes our understanding of trichomonad core metabolism and opens the door for the research of unexplored metabolic capabilities of this parasite.
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Function and structure of hydrogenases and their occurence in organisms
Košťálová, Alena ; Hrdý, Ivan (advisor) ; Šuťák, Róbert (referee)
Hydrogenases are microbial enzymes catalyzing reversible oxidation of molecular hydrogen. These enzymes are mostly found in prokaryotes, but a few of them are present in eukaryotes as well. Hydrogenases are metalloproteins which are classified into three classes, [NiFe]-, [FeFe]- and [Fe]-hydrogenases, based on the composition of the active site. [NiFe]-hydrogenases are heterodimeric proteins with the active site localized in the large subunit. [FeFe]-hydrogenases are mostly monomeric and their active site is called H-cluster. Hydrogenases often possess additional domains that contain redox centers, mostly iron-sulfur clusters. Most of the accessory domains of hydrogenases are homologous to other redox complexes, e. g. Complex I of respiratory chain. Maturation of hydrogenases is a complex process involving the activity of several proteins, some of which have been already partially characterized. Compelling evidence indicates that [NiFe]- and [FeFe]-hydrogenases are phylogenetically distinct classes of proteins. This work deals with the differences among hydrogenases including their function, structure, maturation and distribution, and also mentions their similarities with other enzymes.
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Mitochondrion of Trimastix pyriformis
Novák, Lukáš ; Hampl, Vladimír (advisor) ; Kolísko, Martin (referee)
2013 DIPLOMOVÁ PRÁCE Lukáš Novák Abstract Free-living microaerophilic protist Trimastix pyriformis is closely related to oxymonads which are the largest eukaryotic group without any known mitochondrion. In contrast to oxymonads, an enigmatic reduced mitochondrion has been found in the cell of T. pyriformis. In EST data of T. pyriformis, a number of genes has been identified whose products are putatively localized in the mitochondrion. Among these are genes for all the components of the glycine cleavage system, [FeFe]hydrogenases and the mitochondrial marker Cpn60. We performed experiments in order to determine the cellular localization of these proteins. Our results show that the glycine cleavage system is localized in the mitochondrion. Results of the experiments carried out in order to localize two hydrogenases suggest also the mitochondrial localization but are not fully convincing. The attempt to localize Cpn60 has failed. We have also identified a set of new genes in transcripts of T. pyriformis and Monocercomonoides sp. (Oxymonadida). These genes code for some components of the SUF system of FeS cluster synthesis and a peroxidase rubrerythrin. Key words: Trimastix, Monocercomonoides, mitochondrion, hydrogenosome, mitosome, hydrogenase, glycine cleavage system, SUF system.
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