The fundamental element of life known to man is the gene. The information contained in genes regulates all cellular functions, in health and disease. The ability to selectively alter genes or their transcript intermediates with designed molecular tools, as synthetic oligonucleotides, represents a paradigm shift in human medicine. The full potential of oligonucleotide therapeutics is however dependent on the development of efficient delivery vectors, due to their intrinsic characteristics, as size, charge and low bioavailability. Cell-penetrating peptides are short sequences of amino acids that are capable of mediating the transport of most types of oligonucleotide therapeutics to the cell interior. It is the interaction of cell-penetrating peptides with oligonucleotides and the transport of their non-covalently formed complexes across the cellular membrane, that constitutes the main subject of this thesis. In Paper I we studied the effects of different types of oligonucleotide cargo in the capacity of cationic and amphipathic peptides to interact with lipid membranes. We found that indeed the cargo sequesters some of the peptide’s capacity to interact with membranes. In Paper II we revealed the simultaneous interaction of different molecular and supramolecular peptide and peptide/oligonucleotide species in equilibrium, with the cellular membrane. In Paper III we developed a series of peptides with improved affinity for oligonucleotide cargo as well as enhanced endosomal release and consequently better delivery capacity. In Paper IV we investigated the effect of saturated fatty acid modifications to a cationic cell-penetrating peptide. The varying amphipathicity of the peptide correlated with the complex physicochemical properties and with its delivery efficiency. This thesis contributes to the field with a set of characterized mechanisms and physicochemical properties for the components of the ternary system – cell-penetrating peptide, oligonucleotide and cell membrane – that should be considered for the future development of gene therapy. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.</p>

La présence de contaminants métalliques dans les produits pétroliers engendre des effets indésirables, comme la dégradation de leur stabilité au stockage. Pour limiter ces perturbations, des additifs sont incorporés aux produits pétroliers dans le but de complexer les cations métalliques en solution. Le sujet de la thèse porte sur le développement d’une méthodologie pour étudier les interactions non covalentes dans une matrice hydrocarburée par spectrométrie de masse électrospray (ESI-MS). Plusieurs approches ont été utilisées pour comparer le pouvoir complexant de différentes molécules vis-à-vis des métaux ciblés, puis identifier les structures chimiques les plus efficaces pour inhiber l’action catalytique des contaminants. Ces travaux mettent en évidence l’apport de l’ESI-MS comme outil de présélection d’additifs, moins coûteux et chronophage que les méthodes actuelles de screening. / The contamination of petroleum products by metallic compounds leads to adverse effects, as the degradation of their stability under storage. To prevent these phenomena, specific molecules are added to petroleum products in order to complex metallic cations in solution. This work focus on the development of an electrospray mass spectrometry (ESI-MS) method to study non covalent interactions in a hydrocarbon medium. Several approaches were employed to compare the complexing ability of different molecules towards targeted metals, then to identify the most efficient chemical structures to inhibit the catalytic action of contaminants. Results highlight the contribution of ESI-MS as a screening tool, less expensive and time-consuming than the methods currently used.

Charles University Faculty of Pharmacy in Hradec Králové Department od Biochemical Sciences Candidate: Růžena Melicharová Supervisor: PharmDr. Anna Jirkovská, Ph.D. Title of thesis: The detection of protein covalent complexes with DNA using fluorescent microscopy Anthracycline antibiotics are present one of the most potent antineoplastic drugs. The mechanism of their action is complex. They are reported to intercalate to DNA, form DNA adducts and interact with topoisomerase II (TopII) as its poisons. Catalytic cycle of TopII is interrupted when anthracyclines stabilize the covalent complex of DNA and TopII and that causes cell damage. However, using of anthracyclines is limited by several adverse effects e. g. myelotoxicity and cardiotoxicity. The mechanism of cardiotoxicity is still unclear but may be associated with poisoning of the TopIIβ isoform. Unlike the TopIIα, TopIIβ is present mostly in quiescent cells as cardiomyocytes. Furthermore, the only clinically approved cardioprotective drug dexrazoxane belongs to TopII catalytic inhibitors. Nevertheless, the details of the dexrazoxane-afforded protection are unclear. This thesis was aimed to optimize the TARDIS (trapped in agarose DNA immunostaining) assay to detect and quantify covalent cleavage complexes, compare different ways for analysis of...

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