National Repository of Grey Literature 52 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Enzyme activity analysis of function domains belonging to model heme-containing sensor proteins
Prošková, Veronika ; Martínková, Markéta (advisor) ; Macek, Tomáš (referee) ; Vítek, Libor (referee)
EN This Ph.D. thesis focuses on the heme containing gas sensor proteins. These proteins are predominantly present in bacteria, in which play an important role in processes like, sporulation, antibiotic resistance and so on. Heme containing sensor proteins composed of two domains. First one is a globin domain, which contains the heme molecule. Interaction of heme with gas molecule acts as a signal for the activation/inactivation of the second functional domain. Part of this thesis is formed by a review, which summarized the current knowledge about heme containing sensor proteins. In the next part of this thesis we focused on three representatives from the group of oxygen sensor proteins - histidine kinase AfGcHK, diguanylate cyclase YddV and phosphodiesterase EcDOS. The main aim of this thesis was to solve the mechanism of interdomain/intraprotein signal transduction in two oxygen sensor proteins with globin fold of their sensor domain (AfGcHK, YddV). For this purpose, we used the kinetic analysis of their functional domain activity and the methods of structural biology. We also studied the mechanism of interprotein signal transduction in AfGcHK and its cognate partner RR protein. It was also tested, how the presence of sodium disulfide affects the functional properties of oxygen sensor proteins...
Biogenní aminy v potravinách
Macek, Tomáš
The bachelor thesis deals with an issue of biogenic amines ocurring in food. It describes of biogenic amines formation, charakteristics, factors influencing their content, toxic effects on human health and also their degradation in the human body. Then the thesis focuses on biogenic amines occurrence in various types of food. It also describes microorganisms which are involved in biogenic amines formation. At the end of the thesis there is paid attention to prevention of biogenic amines occurence in food at levels that may cause health problems.
Enzymatic and Metabolic Transformation of Silybin and its Congeners
Purchartová, Kateřina ; Křen, Vladimír (advisor) ; Macek, Tomáš (referee) ; Vítek, Libor (referee)
Natural flavonoids and flavonolignans feature beneficial properties for living organisms such as antioxidant and hepatoprotective effects, anticancer, chemoprotective, dermatoprotective and hypocholesterolemic activities. Their metabolism in mammals is complex, the exact structure of their metabolites still remains partly unclear and the standards are usually not commercially available. Hence, this project focused on the preparation of potential and defined biotransformation Phase II sulfated metabolites of silymarin flavonolignans: silybin, 2,3-dehydrosilybin, isosilybin, silychristin, silydianin and flavonoids quercetin, taxifolin, rutin and isoquercitrin. Pure sulfated derivatives were prepared using aryl sulfotransferase from Desulfitobacterium hafniense and aryl sulfotransferase from rat liver. Using heterologously expressed PAPS (3'-phosphoadenosine-5'-phosophosulfate) - independent arylsulfotransferase from Desulfitobacterium hafniense and cheap p-nitrophenyl sulfate as sulfate donor, sulfated flavonolignans and flavonoids were obtained in high yields. Silymarin flavonolignans afforded exclusively monosulfates at the position C-20 (C-19 in the case of silychristin), except 2,3-dehydrosilybin that yielded also the 7,20-O-disulfated derivative. Isoquercitrin and rutin were selectively sulfated...
Molecular mechanisms of signal transduction in model heme-containing oxygen sensor proteins
Stráňava, Martin ; Martínková, Markéta (advisor) ; Obšil, Tomáš (referee) ; Macek, Tomáš (referee)
EN Heme containing gas sensor proteins play important role in bacterial physiology in regulating many processes such as cell differentiation, virulence, biofilm formation or intercellular communication. For their structure, typical modular architecture is characteristic where various sensor domains (usually at the N-terminus) regulate the activity of the catalytic or functional domains (usually at the C-terminus). In this dissertation thesis, we focused on three representatives from the group of oxygen sensing proteins, namely histidine kinase AfGcHK, diguanylate cyclase YddV, phosphodiesterase EcDOS and also on protein RR, which is the interaction partner of AfGcHK. The main aim of the thesis was to study intra-protein/inter-domain signal transduction in two representatives of heme sensor proteins with a globin fold of the sensor domain (AfGcHK, YddV) and in one representative with PAS fold of the sensor domain (EcDOS). Another objective was to describe inter-protein signal transduction in the two component signaling system AfGcHK-RR and structurally characterize these two interacting partners. Emphasis was also placed on the study of the interaction between model sensor domains and different signaling molecules and also on function of individual amino acids involved in the binding of these...
Study of function and molecular architecture of fungal nitrilases applicable in biocatalysis
Veselá, Alicja Barbara ; Martínková, Ludmila (advisor) ; Macek, Tomáš (referee) ; Teisinger, Jan (referee)
Nitrilases are enzymes which catalyze the hydrolysis of a nitrile into the corresponding carboxylic acid and ammonia. These enzymes are potentially applicable in biocatalysis and bioremediation because of their advantages over the conventional (chemical) methods of nitrile hydrolysis (lower demand for energy, safety, simplicity, high yields, selectivity). In this work, genome mining was used to search for the sequences of hypothetical nitrilases from filamentous fungi. The amino acid sequences of previously characterized fungal nitrilases were used as the templates. Then the new synthetic genes together with other genes from our nitrilase library were expressed in E. coli and the substrate specificities of the enzymes thus produced were compared. Significant attention was focused on the relationships between the sequence of the enzyme and its substrate specificity. The arylacetonitrilases from Arthroderma benhamiae (NitAb) and Nectria haematococca (NitNh) were purified and characterized. Their substrate specificities, kinetic parameters, pH and temperature profiles and subunit and holoenzyme size were assessed. NitAb and NitNh together with other recombinant fungal nitrilases were employed in the hydrolysis of high concentrations of (R,S)-mandelonitrile in a batch or fed-batch mode. Nitrilase from...
The Psychological Aspects of Navigation of the Blind
Franc, Jakub ; Kebza, Vladimír (advisor) ; Horáková Hoskovcová, Simona (referee) ; Macek, Tomáš (referee)
This dissertation thesis addresses the area of spatial navigation of the blind. The author theoretically deals with a complex interplay of psychological functions involved in spatial navigation with respect to the specific conditions of the blind. The empirical part of the thesis presents an experimental study in the population of the blind (N=44). This study focuses on effects of the stress recovery phase from shortly increased stress levels on the process of learning a new route. The experiment is placed in real-world settings and overcomes some of the methodological flaws typical for this research domain. The research evidence suggests that the recovery phase from shortly increased stress levels hinders the development of procedural knowledge of the route. However, this deterioration in route knowledge is not associated with the effects of the strsss phase itself, but affects only the recovery phase part of the route in which stress levels are returning to their original baseline levels (not necessarily the level of the resting conditions). Besides its theoretical conclusions, the value of the presented thesis is in its contribution to the advancements of research methods in the given field. The outcomes of this work are practically applicable to the development of navigation aids for the blind....
Antimicrobial peptides isolated from the venom of hymenopterous insect
Monincová, Lenka ; Čeřovský, Václav (advisor) ; Macek, Tomáš (referee) ; Fusek, Martin (referee)
Rapid development of bacterial resistance and multiresitance to conventional antibiotics has resulted in an intensive search for alternative antimicrobial agents. Antimicrobial peptides (AMPs) belong to promising anti-infective candidates since they do not development bacterial resistance. They kill microbes by disturbing or permeabilizing the cytoplasmic membrane, or may target putative key intracellular compartments. Their advantages include fast action and selectivity between prokaryotic and eukaryotic cells. We have isolated several novel AMPs from the venom of wild bees: halictines (HAL-1 and HAL-2) from Halictus sexcinctus, lasiocepsin (Las) from Lasioglossum laticeps and macropin (MAC-1) from Macropis fulvipes. They are active against Gram-positive and Gram- negative bacteria and against yeast Candida albicans. While halictines and macropin have moderate hemolytic activity, Las shows no hemolytic activity. A novel AMP was isolated also from the mucus of Xiphydria camelus. This AMP belongs to the category of insect defensins. It contains 55 amino acid residues, three disulphide bridges and its C-terminus is amidated. CD and NMR studies of HAL-1, HAL-2 and MAC-1 revealed propensity to form amphipathic α-helical structure in the presence of sodium dodecyl sulfate or trifluoroethanol. For the...
Fungal Biodegradation of Endocrine Disruptors
Křesinová, Zdena ; Cajthaml, Tomáš (advisor) ; Macek, Tomáš (referee) ; Smrček, Stanislav (referee)
This dissertation thesis contains scientific results attained in the field of bioremediation. The major part of the results has been published in international journals in 7 papers. In addition, relevant yet unpublished results have been included too. The first thematic part describes the screening of the degradation ability of white rot fungi (WRF). In the screening, several endocrine-disrupting compounds (EDs; bisphenol A, triclosan, 4-nonylphenol and 17α-ethinylestradiol) were degraded by 8 different fungal strains in the presence of liquid medium. The most promising strains were used for the degradation of an ED mixture (synthetic and natural estrogens) in the presence of a straw substrate. Attention was paid to the evaluation of stimulation or suppression of enzyme activities during the biodegradation processes and changes in residual estrogenic activity. Pleurotus ostreatus, Irpex lacteus and Trametes versicolor showed the highest degradation ability under both cultivation conditions. On the contrary, Phanerochaete chrysosporium, to date the most studied representative of white rot fungi, did not degrade bisphenol A and 17α-ethinylestradiol (EE2) at all. Two review articles have been published to summarize the origin, presence and biodegradation of EDs, mainly EE2, in the environment. The...
Structure and biocatalytic properties of nitrilases from filamentous fungi
Křenková, Alena ; Martínková, Ludmila (advisor) ; Macek, Tomáš (referee) ; Klempier, Norbert (referee)
Filamentous fungi are alongside bacteria a rich source of nitrilases that can be used for biotechnological purposes. There is a large number of sequences of putative nitrilases in databases, but few of these enzymes have been expressed, purified and characterized. According to the sequences in GenBank database, synthetic genes of putative nitrilases from Aspergillus niger CBS 513.88 and Neurospora crassa OR74A were designed, expressed in Escherichia coli and the nitrilases produced were purified and characterized. The effect of chaperone-assisted nitrilase expression was also examined using a set of commercial chaperone plasmids. The structural properties of nitrilases were examined using various methods, such as homology modelling, sedimentation velocity analysis or electron microscopy. Recombinant nitrilase production was compared to their production by native producers - filamentous fungi. The cultivation of native producers was rather difficult and nitrilase production was very low, therefore, the advantage of using prokaryotic expression system was highlighted. Nitrilases with amino acids close to the catalytic cysteine replaced were prepared in order to study the effects of certain amino acids on the activity, chemoselectivity and enantioselectivity of nitrilases. The catalytic properties of...
Accumulation of Zn, Cd and Pb in Agriculturally Important Cereals and Their Possible Genetic Modifications
Jarolímková, Víta ; Macek, Tomáš (advisor) ; Rothová, Olga (referee)
Cadmium, lead and zinc are taken up by plants from soil and atmosphere. Afterwards, they are redistributed within the plant body and often deposited in the parts that are processed in the food industry. Vegetal food therefore considerably contributes to the acquisition of essential zinc, but also to the accumulation of toxic cadmium and lead in the human body. As zinc deficiency and, on the other hand, cadmium and lead intoxication are global problems, accumulation of these metals is a topical issue. Increase in zinc deposition and decrease in cadmium and lead accumulation can be reached not only by traditional breeding and soil modification, but also by gene engineering methods. Soon, Zn-biofortified crops prepared via traditional breeding will be tested on a large-scale; overexpression of zinc ligands is researched as well. However, use of cisgenic or transgenic expression of plant metal transporters is currently a rather unexplored topic; yet it has the potential to target both the need for Zn-biofortification and decrease in cadmium and lead accumulation in edible parts of crops.

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