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Heterologous expression and purification of human cytochrome b5
Kostelanská, Marie ; Černá, Věra (advisor) ; Bořek Dohalská, Lucie (referee)
The metabolism of xenobiotics and endogenous substances is mediated by a mixed function oxidase system which includes cytochrome b5 participating in catalytic activities of CYP. The mechanism of action of the cytochrome b5 has not been fully elucidated yet. But it is assumed that cytochrome b5 is involved either in direct electron transfer within the mixed function oxidase system or in induction of conformational changes in CYPs. So it is important to gain the pure form of apo-cytochrome b5, devoid of heme, which is not capable of electron transfer and further study the effect of this form on CYP-catalyzed reactions. The obtained results can contribute to understanding the mechanism of cytochrome b5 effects. The transformation of bacterial cells of Escherichia coli BL-21 (DE3) Gold was performed by expression vector pET22b which contained genes for microsomal and erythrocyte cytochrome b5. In order to produce a high level of apoprotein form, the heterologous expression of cytochrome b5 was induced by addition of higher amount of IPTG. Expression was performed at 37řC. This bachelor thesis is primarily engaged in purification of both microsomal and erythrocyte form of cytotochrom b5, especially in its apo-form. However, the productions of holo-cytochrome b5 form always occur in a greater or lesser...
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Study of the photodynamic inactivation of prions by phthalocyanines.
Kostelanská, Marie ; Holada, Karel (advisor) ; Zimčík, Petr (referee) ; Kolářová, Hana (referee)
Transmissive spongiform encephalopathies, also called prion disorders, are fatal neurodegenerative diseases affecting mammals. In patients, the pathological prion protein (PrPTSE ) accumulates in CNS and causes death. Prions possess high binding affinity to surfaces. Moreover, they are highly resistant to conventional sterilization procedures which rise the risk of nosocomial transmission from patients in subclinical stage of prion disease through medical tools. In the thesis, we evaluate the efficiency of photodynamic inactivation (PDI) for prion decontamination. The PDI is induced by photoactivation of phthalocyanine (Pc) derivates AlPcOH(SO3)2, SiPc(OH)2(SO3)1-3 or ZnPc(SO3)1-3. Pc exposed to light generate reactive oxygen species, mainly singlet oxygen (O2(1 ∆g)). Production of O2(1 ∆g) in aqueous solution was confirmed by iodide method, quenching by NaN3 and oxidative degradation of uric acid. The photoactivation of Pc in infectious brain homogenate led to elimination of PrPres signal (= proteinase K-resistant PrPTSE fragment) below the detection limit of western blot by using nanomolar AlPcOH(SO3)2 concentration. The complete elimination of PrPres signal was accompanied with total protein concentration decrease by a maximum of 20% in brain homogenate No signs of protein fragmentation or...
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Heterologous expression and purification of human NADPH: cytochrome P450 oxidoreductase
Kostelanská, Marie ; Černá, Věra (advisor) ; Kavan, Daniel (referee)
NADPH: cytochrome P450 oxidoreductase (POR) is an enzyme that is able to catalyze transfer of electrons from NADPH, via two-flavin cofactors, to various redox partners. Therefore, POR is essential for multiple metabolic processes, including reactions catalyzed by cytochromes P450. Due to all microsomal P450s depending on POR for the supply of electrons, disruption of POR may affect all microsomal P450 enzyme activities. Polymorphisms in human POR have been shown to lead to development phenotypes, the severity of which differs significantly depending on the degree of POR impairment. This thesis is focused on the preparation of POR, which is similar to combinatorial allele carrying two single nucleotide polymorphisms P228L and A503V, functionally not clearly characterized at that time. However, disastrous consequences have currently not been noted. Moreover, the presence of A503V has been confirmed as the most common allele, but there is evidence that A503V influences the activity of some redox partners. In present thesis there were two genes subcloned into expression plasmids pCW. The first of which carries the cDNA encoding the POR and the other carrying cDNA encoding POR with the histidine-tag. Expression of the recombinant POR was carried out in the heterologous bacterial system, using...
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Heterologous expression and purification of human cytochrome b5
Kostelanská, Marie ; Černá, Věra (advisor) ; Bořek Dohalská, Lucie (referee)
The metabolism of xenobiotics and endogenous substances is mediated by a mixed function oxidase system which includes cytochrome b5 participating in catalytic activities of CYP. The mechanism of action of the cytochrome b5 has not been fully elucidated yet. But it is assumed that cytochrome b5 is involved either in direct electron transfer within the mixed function oxidase system or in induction of conformational changes in CYPs. So it is important to gain the pure form of apo-cytochrome b5, devoid of heme, which is not capable of electron transfer and further study the effect of this form on CYP-catalyzed reactions. The obtained results can contribute to understanding the mechanism of cytochrome b5 effects. The transformation of bacterial cells of Escherichia coli BL-21 (DE3) Gold was performed by expression vector pET22b which contained genes for microsomal and erythrocyte cytochrome b5. In order to produce a high level of apoprotein form, the heterologous expression of cytochrome b5 was induced by addition of higher amount of IPTG. Expression was performed at 37řC. This bachelor thesis is primarily engaged in purification of both microsomal and erythrocyte form of cytotochrom b5, especially in its apo-form. However, the productions of holo-cytochrome b5 form always occur in a greater or lesser...
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