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N-oxides of morphinan alkaloids
Palušák, Martin ; Dračínská, Helena (advisor) ; Chmelík, Josef (referee)
Morphinan alkaloids belong to important class of compounds acting as painkillers. Understanding of the mechanism of their action is important for improved therapy using these alkaloids, for example, through the synthesis of new analogues with improved effect. The goal of this work is to summarize existing knowledge of these compounds including information about their biosynthesis in the plants and overall effect on the organism. The goal of the practical part of the work is a determination of the relative configuration of morphinan N-oxides produced by in situ oxidation of parent alkaloids using NMR spectroscopy and molecular modelling. Relative configurations of both oxidized and non-oxidized forms of morphine, codeine and thebaine were analyzed using NMR spectroscopy. NMR spectra were analyzed to detect ratio of different N-oxide products in situ. These values were compared with results of DFT quantum chemical computation. Using correlation analysis, reliability of computational method was verified. (in Czech) Key words: NMR spectroscopy, morphine, codeine, thebaine, N-oxides, metabolism of alkaloids
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Preparation of the soluble form of a mouse NKR-P1A protein for the NMR study
Skála, Kristián ; Chmelík, Josef (advisor) ; Adámková, Lyubina (referee)
Natural killer cells (NK cells) are a type of lymphocyte. According to their function they are defined as cytotoxic cells which cause cell death without prior sensitization. NKR-P1 is one of the families of NK surface receptors. This family belong to C-type lectin like with inhibitory or activatory function. In this work we concern of soluble form of mouse protein Nkr-p1a, that is isoform of activatory receptor Nkr-p1a. This receptor is expected to be intracellular due to lack of major part of its transmembrane domain. We focus on the optimization of Nkr-p1a production parameters. As production system we used bacterial strain E. coli BL21(DE3) Gold, in which the target protein is produced and subsequently isolated in the form of inclusion bodies. Obtained recombinant protein was refolded and purified. As purification step we used high-performance liquid chromatography. We optimized concentration of inductor of expression, production time and temperature. The objective is to set up protocol for preparation of isotopically labeled protein for nuclear magnetic resonance structure characterization. (in czech)
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Co-operativity of cytochrome P450 system and its impact on drug and carcinogen metabolism
Holý, Petr ; Hodek, Petr (advisor) ; Chmelík, Josef (referee)
The system of mixed-function oxidases (MFO system) has a significant role in metabolism of many endogenous compounds, as well as xenobiotics (for ex. karcinogens, drugs). Membrane-bound haemoproteins called cytochromes P450 are a vital part of that system. Reactions catalyzed by cytochromes P450 are influenced by another protein of the MFO system, cytochrome b5. The mechanism of this cyt b5 agency has not yet been fully described. One of methods used for study of this protein-protein interaction is covalent cross- linking. By replacing one of three methionines in the cyt b5 structure by a photo-reactive analogue (photo-methionine), an analogue of cyt b5 (photo-cyt b5) can be obtained. When activated by UV radiation, the protein covalently bonds cytochrome P450 in a membrane environment. This paper focuses on expression and isolation of a recombinant cyt b5 analogue with only one methionine position (96) in the protein structure and substitution by photo-methionine. Protein was purified in a yiedl of 6 mg from 1 liter of baterial suspension. Analysis by mass spectrometry (MALDI-TOF/TOF) showed methionine to have been substituted by the photo-reactive analogue in approx. 30 %. Photo-cyt b5 was used to fixate transient protein-protein interactions with cytochrome P450 2B4 (CYP2B4). Photo-cyt b5 was...
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Interaction of Cytochromes P450 with Flavodoxin: a theoretical study
Culka, Martin ; Martínek, Václav (advisor) ; Chmelík, Josef (referee)
Cytochromes P450 are diverse group of heme enzymes found in most species on Earth. In humans they are involved in metabolism of foreign compounds or steroids, bacteria employ cytochromes P450 for utilization of various hydrophobic substrates. General reaction catalyzed by cytochromes P450 is monooxygenation, when one atom of oxygen molecule is introduced into the substrate, while the other is reduced producing water. NADPH:cytochrome P450 oxidoreductase or cytochrome b5 usually serves as an electron donor providing electrons needed for activation of oxygen in eukaryotic organisms, in bacteria small FeS proteins or flavoproteins are these electron donors. It was shown earlier that bacterial electron donor flavodoxin could also interact with human cytochromes P450 in vitro. This thesis employs molecular modeling techniques to support a hypothesis that flavodoxin is responsible for reduction of human (1A2, 2A6, 2A13, 2C9, 2C19, 3A4) and bacterial (101A1 a 176A1) cytochromes P450 heterologously expressed in Escherichia coli. An initial guess of possible mutual orientations of cytochrome P450 and flavodoxin was predicted using information-driven protein-protein docking. The stability of these complexes was examined by directed dissociation method. The most stable orientation for each cytochrome P450 was further...
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Protein fractionation and relative quantitation using PF 2D and ITRAQ for biomarker quest
Gadher, S. J. ; Skalníková, Helena ; Halada, Petr ; Řehulka, Pavel ; Chmelík, Josef ; Kovářová, Hana
ProteomeLab PF 2D System - Protein Fractionation in 2 Dimensions (Beckman Coulter, Fullerton, CA, USA) has been developed to fractionate complex protein mixtures by chromatofocusing in the first dimension followed by high-resolution non-porous silica reversed phase chromatography (RP LC) in the second dimension. Despite the high-resolution power of ProteomeLab PF 2D, UV-based quantitation could be compromised due to possible co-elution of several proteins into one fraction. Hence, we present an optimized protocol for application of isobaric tags for relative and absolute quantitation (iTRAQ) and MALDI-TOF/TOF mass spectrometry to obtain quantitative data from peptides derived by tryptic digestions of intact proteins fractionated by ProteomeLab PF 2D technique. To demonstrate the feasibility of such an approach, protein expression patterns obtained from the ProteomeLab PF 2D fractionation of human T-lymphoblastic leukemia CEM cell line were utilised.
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Influence of the laser power and analyte concentration on the results in MALDI-TOF MS of oligosaccharides
Čáslavský, Josef ; Chmelík, Josef
MALDI-TOF MS has been successfully applied for the analysis of a wide range of organic biopolymers including oligosaccharides. We focus our attention to the group of oligosaccharides occuring in beer and in malting and mashing products, which are mainly oligosaccharides containing from 3 to more than 30 glucose units in their molecules. We tried to evaluate various factors influencing the obtained results. We found that the shape of the spectrum depends significantly on the energy of ionising laser pulse and also on the amount of the analyte on the MALDI target. These effects were studied with standard mixtures as well as with real samples.
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