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Kinetic properties of β-N-acetylhexosaminidase from tobacco plants
Valenta, Robert ; Ryšlavá, Helena (advisor) ; Šulc, Miroslav (referee)
β-N-acetylhexosaminidase from tobacco leaves (Nicotiana tabacum L.) was partially purified to final specific activity 1,72 µmol . min-1 . mg-1 using p-nitrofenyl-β-N- acetyl-D-glucosaminide as substrate. The enzyme exhibited one band after both isoelectric focusing and native electrophoresis. Molecular mass of native enzyme was determined by gel chromatography (MR 275000) and native electrophoresis (MR 285000). Isoelectric point pI 5.4 was determined by isoelectric focusing. Activity of β-N-acetylhexosaminidase was measured using substrates p-nitrofenyl-β-N-acetyl-D-galactosaminide, p-nitrofenyl-β- N-acetyl-D-glucosaminide, N,N'-diacetylchitobiose, p-nitrofenyl-N,N'- diacetylchitobioside and N,N',N''-triacetylchitotriose. For substrates N,N'- diacetylchitobiose, p-nitrofenyl-N,N'-diacetylchitobioside and N,N',N''-triacetylchitotriose an enzyme assay of β-N-acetylhexosaminidase using capillary zone electrophoresis was developed. Optimal pH and temperature of β-N-acetylhexosaminidase were determined with individual substrates, as well as products of hydrolysis. Activity of β-N- acetylhexosaminidase was highest using p-nitrofenyl-β-N-acetyl-D-glucosaminide as substrate and lowest using N,N',N''-triacetylchitotriose (35% in relative comparison). Maximum velocity and Michaelis constant of...
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Preparation of mutated forms of fosfatidylinositol kinase IIα
Gregor, Jiří ; Šulc, Miroslav (advisor) ; Košek, Dalibor (referee)
Phosphatidylinositol 4-kinases (PI4K) are enzymes that form phosphatidylinositol-4- phosphate, which is an important regulatory molecule and precursor for the synthesis of other regulatory molecules. PI4K are interesting from medical aspect, because of connection between their function and viral, malignant, metabolic and neurodegenerative diseases. PI4K type II are inhibited by calcium cations, whereas PI4K type III aren't. The goal of this thesis was to elucidate the relationship between structure and regulation of function of PI4K IIα, specifically regulation by calcium cations. We failed in preparation of mutated forms of PI4K IIα that wouldn't be inhibited by calcium cations. However, the results obtained suggest, how aminoacids N313, D346 and E193 affect the kinase activity of PI4K IIα. (In Czech)
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A study of the temperature sensitivity of the human TRPA1 channel
Barvíková, Kristýna ; Šulc, Miroslav (advisor) ; Černá, Věra (referee)
Transient receptor potential (TRP) ion channels play important physiological roles in the detection of environmental stimuli that occur primarily at the peripheral terminals of specialized sensory neurons. The recently resolved cryo-electron microscopy structures and molecular biological techniques have provided new tools that enable to study these channels in relation to their function, and thus to understand more deeply their pharmacology and physiology. The aim of this bachelor thesis is to give an overview of the current status of research on the ankyrin TRP channel subtype 1 (TRPA1), a channel activated by diverse irritant chemical stimuli but also by temperature changes. The experimental part is focused on the elucidation of the role of the sensor domain in thermal sensitivity of the TRPA1 channel. Using whole-cell patch-clamp electrophysiological technique, the presented results demonstrate that the sensor is an important determinant of voltage-dependent gating. Mutation of the conserved tyrosine in the center of the sensor resulted in channels with clearly different activation kinetics and increased chemical responses upon increasing the temperature from 25 řC to 35 řC. Key words: TRP ion channel, ankyrin receptor, nociception, structure-function, carvacrol
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Excitation of molecules by cold electrons
Šulc, Miroslav ; Horáček, Jiří (advisor) ; Čárský, Petr (referee) ; Čížek, Martin (referee)
Title: Excitation of molecules by cold electrons Author: Miroslav Šulc Department / Institute: Institute of Theoretical Physics, Charles University in Prague Supervisor of the doctoral thesis: prof. RNDr. Jiří Horáček, DrSc., Institute of Theoretical Physics, Charles University Abstract: Several methods for low energy collisional processes are investigated. In the first part, attention is especially devoted to examination of applicability of the R-matrix method combined with the Schwinger-Lanczos (SL) variational principle for potential scattering with long-range forces. Next sections deal with the development of the interaction correlation-polarization (CP) potential in the framework of the Dis- crete Momentum Representation (DMR) method on the grounds of the Local Density Approximation in the Density Functional Theory (DFT) context. Obtained results are then utilized in body-frame (BF), static exchange + polarization (SEP), calcula- tions within an analysis of experimental data for e−-N2 scattering comprising a part of a larger project addressing theoretical examination of rotational excitations of small molecules in the gas phase induced by electron impact. For N2, a new phenomenon consisting in suppression of backward cross-section below 95 meV is observed and con- sequently attributed to...
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Study of the microRNAs in patients with head and neck squamous cell carcinoma
Hudcová, Kristýna ; Šulc, Miroslav (referee)
Searching for markers of disease is at the forefront of scientific interest. Biomarker of a specific disease should help in disease management - whether for diagnosing a disease or predicting its progress. We picked microRNAs - short RNAs that regulate mRNA translation, due to their stability and function in the regulation of many cellular processes. Therefore they can be used as a biomarker for many diseases. In our study we focused on neck squamous cell carcinoma (HNSCC), since this type of cancer is widespread and clinically important markers are missing. It is in our interest to seek new kinds of markers, suitable for early diagnosis of the disease and the most accurate assessment of prognosis. We selected 3 candidate miRNA (miR-29c-3p, miR-200b-5p, miR-375-3p) and used qRT-PCR method to profile their expression in tissues of patients with HNSCC. MiRNA expressions in 42 tumor samples were compared with the miRNA expression in adjacent tissue of the tumor. Adjacent tissue surrounds the tumor and has interesting properties, as it looks like a histological normal tissue, but on closer inspection it is not. It is affected by tumor tissue and may contribute to tumor progression. We managed to distinguish between these two tissues using miR-29c-3p and miR-375-3p. Additional analyzes were focused on...
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Clinically relevant protein-protein interactions participating in process of bacterial pathogenesis B. pertusis
Málek, Albert ; Šulc, Miroslav (advisor) ; Černá, Věra (referee)
Whooping cought in human population was strongly suppressed during the 20th century. But in the past few years, the incidence of whooping cough began to rise. The origin of this disease is a pathogenic gram-negative bacteria Bordetella pertussis, which is becoming resistang to currecently used antibiotics or vaccination. B. pertussis attacks human respiratory system. One of it's virulent factors is adenylate cyclase toxin (ACT). It's secreted extracellularly from bacteria and binds to cytoplasmic membrane of host cells and translocates adenylatecyclase domain (dAC) to cytosol. This enzymatic domain is activated by non- covalent interaction with eukaryotic Calmodulin (CaM). After it's activation, dAC in high concentrations synthesizes cAMP, triggering host cell's apoptosis. We studied protein interaction of dAC with CaM by the PIXL method (Photo Induced Cross Linking) and mass spectrometry (MS). Mutant of dAC, with photo-methionine (pM), incorporated in position of Leucine 240 (dACL240pM) was expressed in transformed E.coli cells B834 in mineral medium containing pM. Expressed protein was isolated by affinite chromatography and characterized by MS (determined incorporation of pM was approximately 50 % in the final protein preparation). We performed a photochemical cross-linking with isolated...
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Recombinant expression of RhoA protein with affinity tag.
Filipová, Barbora ; Novák, Petr (advisor) ; Šulc, Miroslav (referee)
The rate of intestinal infections associated with antibiotics has been rising steeply. Virulent toxins of C. difficile, Yersinia and many other bacteria target the RhoA protein. The protein is a GTPase involved in signalling pathways, its major function being the regulation of the actin cytoskeleton. The above mentioned toxins render this protein non- functional, which may lead up to a fatal destruction of the cell. The present diagnostic methods of these infections are insufficient. The use of protein chips and mass spectrometry to detect any RhoA protein modifications seems to provide a feasible method of determining these intestinal bacterial diseases. Therefore the purpose of this study is to use recombinant methods to prepare the desired RhoA protein with a bound affinity probe which will serve to its immobilisation on a biochip. The thus prepared protein will be subsequently used to diagnose the previously described diseases. In Czech.
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Study of structure and interaction of human lymphocyte receptors
Bláha, Jan ; Vaněk, Ondřej (advisor) ; Šulc, Miroslav (referee) ; Obšil, Tomáš (referee)
Natural killer (NK) cells are an essential part of immune system, providing self-surveillance of virally infected, stress transformed or cancerous cells. NKR-P1 receptors and their ligands from clec2 gene family represent an alternate missing-self recognition system of NK cells based on interaction of highly related C-type lectin-like receptors. Human NKR-P1 has been described more than twenty years ago but still remains the sole human orthologue of this receptor family, particularly numerous in rodents. On binding to its cognate ligand LLT1, NKR-P1 can relay inhibitory or co-stimulatory signals. Although being interesting targets for their potential role in tumor immune evasion and autoimmunity, nature of their interaction is still unclear. To elucidate the architecture of their interaction, we developed a generally applicable method for recombinant expression of human NKR-P1 and LLT1 and their homologues based on transfection of HEK293S GnTI- cells. Further, we described a stabilizing mutation His176Cys, that enables for expression of highly stable and soluble LLT1. Finally, we have crystallized LLT1 and human NKR-P1 in different glycosylation states both as individuals and in complex. While both structures of LLT1 and NKR-P1 follow the classical C-type lectin-like superfamily fold, contrary to...
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