Tebuconazole belongs to widely utilized plant fungicides, mostly in vineyards. Its traces are present in plant tissues, wine as well as in soil. The aim of the study was to determine stoichiometries and stabilities of metal (Cu, Zn, Cd, Ca and Ag) complexes with tebuconazole (1) by means of electrospray ionization mass spectrommetry (ESI-MS). It was found that the complexes of tebuconazole with copper ions are particularly stable ([Cu(1)]+ has appearance energy 224 kJ·mol-1 , corresponding with the dissociation of the water molecule from the tebuconazole molecule), while the stability of another tebuconazole complexes is lower, about 150 kJ·mol-1 . In real environmental samples, the detection of 1 itself is hampered by its spreading into various species. The method involved here is based upon a hyphenation of electrochemistry (amperometry) and electrospray-ionization mass spectrometry (ESI-MS). It uses the fact that Cu creates very stable complexes with 1. We demonstrate that at appropriate potentials (at higher than 500 mV) Cu cations can be generated in an electrochemical cell and subsequently form complexes with 1 present in the sample. The resulting complex [Cu(1)]+ is detected with ESI-MS. The intensity of detected complexes depends on the concentration of 1 and the oxidation level of the...

Lanthanide(III) complexes of DOTA derivatives are utilized in the medical imaging techniques such as magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), and magnetic resonance spectroscopy (MRS), nuclear imaging (PET and SPECT), or optical methods (luminescence). It has been shown that relaxometric parameters of the Gd(III) complexes of DOTA derivatives with a phosphinic acid pendant arm (Gd-DO3APR ) can reach optimal values (e.g. water residence time, τM, being close to ~10 ns). The relaxometric parameters can be further modified through the phosphorus substituents. It is also known that the complexes possess a high thermodynamic stability and they are kinetically inert. The main goal of this Thesis is an investigation of the effect of pendant amino group protonation in substituents bound to the phosphorus atom on properties of the complexes. Thus in this Thesis, DOTA derivatives with the phosphinic acid pendant arm with an amino group and their complexes were prepared and characterized. The complexes are intended as contrast agents for molecular imaging techniques (mainly for MRI and 31 P MRS). The first part of the Thesis introduces two new versatile "phospha-Mannich" protocols performed under mild conditions. Amino-H-phosphinic acids (AHPAs) were synthesized with excess of...

Mass spectrometry with electrospray ionization is an excellent method for structural analysis of coordination compounds with outstanding sensitivity and selectivity. However, it fails to detect some low-polar rhenium complexes. This master thesis describes derivatization method of non-ionizable rhenium complexes with 1,2-dihydroxybenzene and 2,3- dihydroxytoluenene. Fragmentation mechanisms and structure of prepared complexes was studied using high resolution mass spectrometry and collision-induced dissociation (CID). Furthermore, density functional theory (DFT) computational method was used for prediction of bond cleavage based on bond lengthening.

ABSTRACT This work is focused on the synthesis of a family of new macrocyclic ligands with exchangeable protons on coordinating groups that could potentially serve (after complexation with suitable paramagnetic lanthanide(III) ions) as responsive contrast agents (CAs) for magnetic resonance imaging (MRI). It is expected that measurement of extracellular pH should bring information for tumorous disease diagnoses and/or for suggesting the most efficient treatment. Therefore, our attention was focused on pH-dependent CAs based on a PARAmagnetic Chemical Exchange Saturation Transfer (PARACEST) mechanism capable of reporting pH changes in tissue. The PARACEST-related properties of a series of Ln(III) complexes with the CEST effect caused by amino groups coordinated to the central Ln(III) metal ions were investigated. Such a kind of PARACEST CA is new and has had no precedent in the literature. It was shown that these Ln(III) complexes produce a pH-sensitive PARACEST effect in the pH region relevant for living systems. The study brings proof-of-principle for utilization of complexes with a linear diamine pendant arm, i.e. complexes with two exchanging proton pools, for ratiometric pH determination by MRI independently on the probe concentration. In addition, to ensure a higher kinetic inertness of the...

Title: Development of novel photoactive cationic zirconocene complexes Author: Bc. David Dunlop Department: Department of inorganic chemistry Supervisor: RNDr. Martin Lamač Ph.D. Advisor: prof. RNDr. Petr Štěpnička, Ph.D., DSc. Abstract: Environmental concerns have brought about an unprecedented demand for sustainable energy sources among which electromagnetic radiation, light, currently dominates. Development of novel light- harvesting compounds and materials is at the forefront of current science, as it is essential to further our technological progress. This thesis contributes to the field by development of novel photoactive cationic group 4 metallocene complexes stabilized by pendant imine and pyridinyl donor groups, or N,O-donor aromatic ligands, as crystalline [B(C6F5)4]− salts. The complexes are prepared either by protonation of the intramolecularly bound imine moiety by PhNMe2H[B(C6F5)4] or by chloride ligand abstraction, by Li[B(C6F5)4]·2.5Et2O or in situ generated Et3Si[B(C6F5)4]. Prepared compounds were characterized by NMR spectroscopy. Solid state structures of the compounds were determined by X-ray diffraction analysis. The cationic complexes of Zr and Hf exhibited significantly enhanced luminescence which originates from triplet ligand-to-metal (3 LMCT) excited states with lifetimes of up to...

The chromatin structure, consisting of DNA and histones, changes dynamically during the cell cycle and cell differentiation. DNA can only be transcribed and replicated when it is packaged loosely, whereas tight packaging allows for more efficient storage. Chromatin remodelling is therefore one of the tools of gene expression control. The chromatin remodelling factors recognise chromatin with varying specificity and have an effect on the interaction between DNA and the histones. One of these factors is the Smarca5 protein. This study investigates the role of Smarca5; its goal is to create a mouse model with the ability to trigger Smarca5 overproduction in specific tissues. This model will be used to study the effect of a high, unregulated dose of Smarca5 on the physiological function of the protein. Previous studies have shown that non-physiological expression of a chromatin-remodelling factor can lead to malignant transformation. Our model can help to understand this process. Another goal of this study is to investigate some phenotype aspects of the mouse model with conditional deletion of Smarca5 in T and B cells, in particular the effects of this deletion on progenitor cell differentiation. Our results show that Smarca5 has an important role in lymphocyte development, and we have observed that...

The aminoacid sequence of papain (EC 3.4.22.2) consists of 212 aminoacids. It has only one free sulfhydryl group, which is located in the active site of the protein. Some organometallic complexes could be bonded only to this free -SH group due to their structure. The artificial metalloproteins synthesised by this way may have different electrochemical properties. In this work, we have studied the electrochemical properties of papain and its derivatives. We compared the ability of papain and its three artificial derivatives to catalyse the hydrogen evolution by the chronopotenciometry. The work was completed by the study of the electrochemical properties of the organometallic complexes of ruthenium, which were used for the artificial metalloprotein preparation. The electrochemical properties of the compounds were never studied before. The process of the hydrogen evolution catalysed by the proteins is held in the adsorbed state of the catalyst. Due to this fact we have also studied the adsorption properties of papain on the substrates with different level of hydrofobicity. (In Czech)

The aim of the diploma thesis is to analyze the mechanisms involved in the coagulation of peptides and proteins contained in cellular organic matter produced by Microcystis aeruginosa, and to describe their influence on the coagulation of hydrophobic kaolin suspension. According to the results of jar tests, the coagulation effectiveness and removability of COM peptides/proteins and kaolin particles are heavily dependent on pH value which determines charge characteristics of peptides/proteins, kaolin and hydrolysis products of coagulant and therefore the prevailing mechanisms of interactions between them. Efficient coagulation and the highest removal of COM peptides and proteins were achieved in the pH range of 4-6 due to charge neutralization of peptide/protein negative surface by positively charged hydrolysis products of ferric coagulant. Peptides and proteins contributed to the coagulation of kaolin particles under the reaction conditions mentioned above, too. Charge neutralization and adsorption were found to be the dominant coagulation mechanisms under these conditions. At a low COM/Fe concentration ratio (COM/Fe < 0.33), adsorption of peptides/proteins onto ferric oxide-hydroxide particles, described as the electrostatic patch model, enabled the coagulation in the pH range of 6-8. On the...

Wnt signalling represents an important mechanism participating in control of cellular and developmental processes, including establishment of cell polarity, cell fate specification, stem cell self-renewal, tissue patterning and organogenesis, homeostasis maintenance and regeneration. Misregulation of the Wnt signalling during embryogenesis leads to developmental defects while aberrant activation later in development is associated with degenerative diseases and a number of cancers. The presented PhD thesis is based on four original publications that deal with the post-translational modifications of Wnt ligands and molecular mechanisms contributing to the regulation of a transcriptional profile of the so-called canonical Wnt pathway. Wnt signalling pathway is used repetitively both in time and different cellular contexts throughout development of multicellular organisms. Inevitably, in each single situation -catenin/TCF complexes, the downstream effectors, induce only subsets of all potential target genes. How this differential tissue- and stage-specific control over various subsets of target genes is achieved with such a limited number of nuclear effectors is not fully understood. Along with the expression of specific LEF/TCF family members or their variants containing different functional domains...

Biopolymer surfactant systems have been studied by using different physico chemical methods. As the biopolymer, it was chosen high (1400–1600 kDa), medium (250–450 kDa) and low (8–15 kDa) molecular weight sodium hyaluronate. Two cationic surfactants – cetyltrimethylammonium bromide (CTAB) and carbethopendecinium bromide (Septonex) were selected to provide polyelectrolyte complexes with oppositely charged hyaluronan. The critical aggregation concentration of the surfactant in the system was monitored by dynamic light scattering (Zetasizer Nano ZS). SEC-MALS method was used for the description of the conformation of sodium hyaluronate of different molecular weights and polyelectrolytes complexes hyaluronan surfactant after reaching the aggregation point. Isothermal titration calorimetry (ITC) was used to determine the critical aggregation concentration of the surfactant by monitoring the thermal changes accompanying the aggregation of the system. It was found out that the increasing molecular weight of hyaluronan in these systems decreases the critical aggregation concentrations and conversely.