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Pyruvate:ferredoxin oxidoreductase homologues from Trichomonas vaginalis hydrogenosomes
Zedníková, Věra ; Hrdý, Ivan (advisor) ; Doležal, Pavel (referee)
Oxidative decarboxylation of pyruvate is a fundamental reaction of living organisms in general, leading to energy conservation. In some anaerobic or microaerophilic eukaryotic or prokaryotic organisms pyruvate decarboxylation is carried out by a single enzyme, pyruvate:ferredoxin oxidoreductase (PFO). PFO contains Fe-S clusters and thiamin pyrophosphate cofactor (TPP). In the reaction catalyzed by PFO, from pyruvate and Co-A arise acetyl-CoA, CO2, and two electrons are released. Those electrons are accepted by low molecular carrier proteins. Most frequently these proteins are ferredoxins or flavodoxins such as in nitrogen fixating bacteria. PFO can perform a reversible reaction. Trichomonads are mostly parasitic or endosymbiotic organisms with mitochondria-like organelles, hydrogenosomes. These organelles possess PFO which is one of the key enzymes in the metabolism of Trichomonas vaginalis hydrogenosomes. PFO of T. vaginalis, a sexually transmitted pathogen of man, plays also a role in a term of medical importance. PFO is, by a universally accepted concept, one of the key proteins acting in the activation of antimicrobial drugs against trichomoniasis 5-nitroimidazoles, including metronidazole. In the genome of T. vaginalis seven PFO genes were identified. They were named PFO A, B1, B2, C, D, E and...
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Characterization of hydrogenosomal iron-sulfur flavoproteins from Trichomonas vaginalis
Pilařová, Kateřina ; Hrdý, Ivan (advisor) ; Kašný, Martin (referee)
Trichomonas vaginalis is flagelated microaerophilic protozoan parasite from Excavata group, which causes trichomoniasis, the most common nonviral sexually transmitted disease in the world. It causes vaginitis in women and uretritis in man and it can also cause problems for example during pregnancy. This thesis is aimed on the characterisation of hydrogenosomal iron-sulfur flavoproteins (ISF) from Trichomonas vaginalis, proteins, which were only recently discovered in the proteome of hydrogenosome of T. vaginalis. Specifically, we have focused on characterisation of ISF3 which is, according to our data, active homodimer and binds flavin mononucleotide (FMN) and iron-sulphur centre in its active site. The iron- sulphur centre is not characterised yet. ISF3 is able to reduce oxygen, hydrogen peroxide, sodium nitrate and metronidazole also in the enzymatic system with PFO and ferredoxin. Next, I tried to reduce ammonium sulphate with ISF3, but unsuccessfully. These results correspond with the activities obtained for ISF from Methanosarcina thermophila, where ISF reduces oxygen and hydrogen peroxide to water. In addition, ISF3 is able to reduce nitrogen compounds. It is important according to the fact, that metronidazole is a drug from the group of 5−nitroimidazoles. The other results show the decrease...
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