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Cytokines in the effector function of regulatory T cells
Zadražil, Zdeněk ; Holáň, Vladimír (advisor) ; Stříž, Ilja (referee)
Regulatory T cells (Treg) are an important control mechanism within the Immune system (IS). Tregs prevent overactivation of effector T cells or autoreactive cells from invading organism-derived tissues. Treg are characterised by expression of surface molecules, CD4, CD25 and by an intracellular transcription factor forkhead box protein 3 (FoxP3). There are two basic populations of Treg, naturally occuring Treg (nTreg) developing in the thymus and induced Treg (iTreg) rising from CD4+ T cells in periphery, which are also precursors for T helper cells. In spite of an outgoing intensive research, there is still no clear clue which mechanisms are used by Treg to inhibit other effector cells. First in vitro experiments showed, that those mechanisms are of a contact dependent manner and do not use secreted molecules. But in vivo experiments showed the exact opposite. Those studies showed that secretory molecules, such as interleukin (IL)-10, IL-35 or transforming growth factor beta (TGF-β), are important in the effectory phase of Treg. Since the first experiments other distinct mechanisms of supression by Treg cells have been discovered. Those mechanisms seem to be important only in particular situations, particular cell assays or with using of specific experimental models. The reasons for this...
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Substrate specificity, mechanism and activity regulation of the rhomboid family intramembrane proteases
Škerle, Jan
Intramembrane proteases from the rhomboid-like superfamily are enzymes widely distributed and conserved in all domains of life. They participate in many important processes such as membrane protein quality control or mitochondrial dynamics. Their activity is also linked with diseases like Parkinson's disease or cancer. This makes them potential therapeutic targets. In this work we tried to elucidate in more detail the mechanism of action of the main model intramembrane protease, GlpG from E. coli. We also focused on the mechanism of eukaryotic rhomboid RHBDL2, one of the four mammalian rhomboids, function of which is poorly understood. To acquire more detailed information about substrate-enzyme interaction, we synthesized a series of novel peptidyl-chloromethylketone inhibitors derived from natural rhomboid substrate TatA from P. stuartii. Crystal structure of the complex of GlpG with these inhibitors revealed four substrate binding subsites (S1 to S4) of the enzyme and explained its observed substrate specificity structurally. This study showed that substrate cleavage rate can be dramatically modified by changing the substrate sequence in positions P1 to P5. This helped us develop fluorogenic transmembrane peptide substrates for rhomboid proteases, which are usable in detergent and liposomes, and...
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Mechanism of microbial biodegradation of polychlorinated biphenyls
Šrédlová, Kamila ; Cajthaml, Tomáš (advisor) ; Kočí, Vladimír (referee) ; Macek, Tomáš (referee)
Polychlorinated biphenyls (PCBs) are chlorinated organic compounds, which belong to persistent organic pollutants and exhibit various modes of toxic action, including mutagenicity, carcinogenicity, and endocrine disruption. PCBs were manufactured during the 20th century in many countries and extensively used due to their advantageous physicochemical properties. PCBs mostly served as insulating liquids in electrical equipment; however, they were also utilized in many open applications. Despite the worldwide ban on PCB manufacture imposed at the end of the 20th century, the contamination of the environment persists to this day as a result of their recalcitrance. Moreover, PCBs are still being inadvertently produced during many industrial activities. Because of their stability, the breakdown of PCBs in nature is extremely slow. This dissertation thesis focuses on the study of PCB biodegradation by ligninolytic fungi. This group of microorganisms belongs to the most promising, especially in regard to the degradation of organic pollutants. The biodegradation mechanism of PCBs was studied in vitro, including the identification of degradation intermediates. Laccase, an enzyme expressed by the oyster mushroom (strain Pleurotus ostreatus 3004), was able to degrade hydroxylated PCBs. In addition, chlorinated...
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Substrate specificity, mechanism and activity regulation of the rhomboid family intramembrane proteases
Škerle, Jan ; Stříšovský, Kvido (advisor) ; Hof, Martin (referee) ; Heidingsfeld, Olga (referee)
Intramembrane proteases from the rhomboid-like superfamily are enzymes widely distributed and conserved in all domains of life. They participate in many important processes such as membrane protein quality control or mitochondrial dynamics. Their activity is also linked with diseases like Parkinson's disease or cancer. This makes them potential therapeutic targets. In this work we tried to elucidate in more detail the mechanism of action of the main model intramembrane protease, GlpG from E. coli. We also focused on the mechanism of eukaryotic rhomboid RHBDL2, one of the four mammalian rhomboids, function of which is poorly understood. To acquire more detailed information about substrate-enzyme interaction, we synthesized a series of novel peptidyl-chloromethylketone inhibitors derived from natural rhomboid substrate TatA from P. stuartii. Crystal structure of the complex of GlpG with these inhibitors revealed four substrate binding subsites (S1 to S4) of the enzyme and explained its observed substrate specificity structurally. This study showed that substrate cleavage rate can be dramatically modified by changing the substrate sequence in positions P1 to P5. This helped us develop fluorogenic transmembrane peptide substrates for rhomboid proteases, which are usable in detergent and liposomes, and...
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Analysis of specific systems of bodies with neutral bonds
Grúz, Jan ; Hájek, Petr (referee) ; Majer, Zdeněk (advisor)
This thesis deals with analytical and graphical solution of three specific systems of bodies that are in static equilibrium. These systems of bodies contain neutral bonds. The opening part dedicates to theory and principles of solution of contact forces in bonds, which are further used for calculations and graphical solutions. The first system of bodies is a demonstrative tappet mechanism which was created for demonstration of some methods of graphical solution. The second system is inspired by lifting mechanisms in production lines. The aim is to find out the magnitude of contact forces for different positions of the lifted weight and a minimal torque of the propulsion. For solving the third system of bodies, principles of statics and hydrostatics are used. The aim is to find out the minimal magnitude of force for activating the mechanism. All systems of equations are solved in Matlab.
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Significance of the S1 subsite of rhomboid intramembrane proteases for catalysis and inhibitor design
Kučerová, Jolana ; Stříšovský, Kvido (advisor) ; Hodek, Petr (referee)
This thesis focuses on the development of specific inhibitors of rhomboid intramembrane proteases. These inhibitors are needed for the cell-biological investigation of rhomboid proteases and their potential pharmacological targeting, as rhomboid proteases have been associated with various diseases, such as malaria, Parkinson's disease, cancer or toxoplasmosis. The thesis advisor's laboratory has recently discovered the first such group of compounds, the peptidyl ketoamides. To exploit them fully, it is necessary to examine their properties and the possibilities of their modifications. In this work, synthetic fluorogenic substrates and enzyme kinetics were used to examine the possibilities of exploiting the S1 subsite in the rhomboid active site for rhomboid inhibitor design. Furthermore, using variants of these substrates modified by unnatural amino acids in the P1 position, the mechanism of water transfer to the rhomboid active site was investigated. Comparison of cleavage rates of ten fluorogenic substrates modified in the P1 position revealed that the E. coli rhomboid protease GlpG strongly prefers side chains -CH2-CH3 and -CH3 in the P1 position (i.e. binding into the S1 subsite). This trend was apparent also with peptidyl ketoamide inhibitors. The present substrate and inhibitor study suggests...
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Construction of boom of loader Dapper
Gregor, Jiří ; Petráš, Jiří (referee) ; Škopán, Miroslav (advisor)
The bachelor thesis deals with the analysis of the current kinematic mechanism of the DAPPER 5000 boom. The second part of the thesis deals with the new mechanism design. The new solution is also analysed kinematically and forcefully. The first part of the thesis is devoted to a description of the DAPPER 5000 and its parts. It is followed by a description of its boom, its analysis and comparison with the booms of competitive loaders. After a critical review of the various boom concepts, where their suitability for the DAPPER 5000 is assessed, a new mechanism for the DAPPER boom is designed. This is followed by a detailed analysis of this mechanism, a basic strength check and, in conclusion, the results of the analyses are summarized, and the meaningfulness of this structural change is evaluated.
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Intake Control Mechanism of Compressor Housing
Bartoníček, Richard ; Doman, Jozef (referee) ; Novotný, Pavel (advisor)
The thesis pursues a design of mechanism for controlling the amount of air sucked by a turbocharger compressor. In the first part, there is a brief description of a turbocharger and its characteristics, in the second part the usual regulation methodologies are presented. Third, the main part describes the creation of the mechanism from concept drafts and their comparison, through the kinematic and force analysis of control parts, to the complete packaging a connection to the compressor housing. The fourth part is dedicated to the mechanism analysis in the terms of ability to perform as required.
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Advanced Magnesium Alloys Surface Modification by Ni-P Based Coatings
Kosár, Petr ; Pacal, Bohumil (referee) ; Nový,, František (referee) ; Havlica, Jaromír (advisor)
The dissertation thesis deals with the modification of the surface of advanced magnesium alloys with Ni-P based coatings. At the beginning of the theoretical part, the structures of the used magnesium alloys and the influence of individual alloying elements on their properties are characterized. In the following part of the thesis the current knowledge in the field of electroless deposition on metal substrates is summarized. The theoretical part of the thesis is closed with contemporary research study in the field of clarification and determination of possible mechanism of electroless deposition. For the subsequent investigation of the mechanism of electroless deposition on magnesium alloys, it was necessary to characterize the microstructure and composition of individual magnesium alloys in the first phase of the experimental part. The exact composition of elements was determined using glow discharge optical emission spectroscopy and scanning electron microscopy with EDS was used for composition of phases of magnesium alloys. Using scanning electron microscopy and detailed elemental analysis of the coated magnesium substrate, it was found that for optimal Ni-P coating deposition on magnesium alloys, acid pickling prior coating is required in a mixture of acetic acid and sodium nitrate. Using the XPS method, it was found that the phosphorus atom in the sodium dihydride-diphosphate reducing agent has a + V charge. 4 At the end of the experimental part scanning electron microscopy and detailed elemental analyses were used for monitoring of the Ni-P particles nucleation and growth in the first 120 seconds of the coating process.
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Overview of the principles of artificial muscles
Buchtová, Blanka ; Knoflíček, Radek (referee) ; Kočiš, Petr (advisor)
This bachelor thesis deals with the research study of principles of artificial muscles activity, used in the field of technical robotics and in the field of micromechanisms. The work involves both devices used commercially and experimentally, including specific applications of artificial muscles and areas of use. This work also includes a case study on the comparison of hydrogel muscle behavior. At the end of the work is evaluation of the experiment and overview of artificial muscles according to the speed of activation.
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