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Interaction of Metal Cations in Bioorganic Environment. Computational Study Using Quantum Mechanics and Molecular MechanicsTools.
Futera, Zdeněk ; Burda, Jaroslav (advisor) ; Bouř, Petr (referee) ; Clark, Tim (referee)
Interactions of Metal Cations in Bioorganic Environment Computational Study Using Quantum Mechanics and Molecular Mechanics Tools Zdeněk Futera Biologically relevant interactions of piano-stool ruthenium(II) complexes with ds-DNA are studied by QM/MM computational technique. The whole re- action mechanism is divided into three phases - hydration of [RuII (η6 - benzene)(en)Cl]+ , consequent binding DNA and final intra-strand cross-link formation between two adjacent guanines. Free energy profiles of all reactions are explored by QM/MM MD umbrella sampling approach where the Ru(II) complex is described by DFT. For that purpose, special QM/MM software was developed to couple Gaussian and Amber programs. Calculated free energy barriers of Ru(II) hydration as well as DNA binding process are in good agreement with experimentally determined rate constants. Reaction pathway for cross-link formation was predicted that is feasible from both thermodynamical and kinetical point of view.
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The Study of hydration models on platinum complexes important in anticancer cure
Bradáč, Ondřej ; Burda, Jaroslav (advisor) ; Záliš, Stanislav (referee)
In this work, there are studied some biologically important platinum complexes, cisplatin analogues, with central platinum atom in state Pt(II), or Pt(IV). I concentrated on the hydration processes of the examined complexes. Thermodynamical and kinetical aspects of reactions were studied and NPA charge analyses were carried out, too. All computations were performed on DFT level with B3LYP functional. All reactions were considered in vacuum. Supermolecular approach was used for energy calculations.
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Quantum mechanical study of the electron hopingp rocesses of heterocyclic molecules.Simulation of absorption and emission spectra.
Tichý, Ondřej ; Burda, Jaroslav (advisor) ; Profant, Václav (referee)
This thesis is about computing lifetimes of excited states of molecules by using semiempirical methods in simulations of molecular dynamics. Pyrimidine nucleobases and three aza- derivatives were chosen as reference molecules. Simulations of molecular dynamics by program MNDO99 were performed with these molecules and static spectra were computed by programs Gaussian and Orca. All the examined molecules have femtosecond lifetimes of second excited states, pyrimidine nucleobases have also short lifetimes of first excited states in hundreds of femtoseconds. The computed first excited states of aza-derivatives have lifetimes in tens or hundreds of picoseconds and suggest that the higher stability of the states is related to the smaller number of amino groups attached to the ring.
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Quantum mechanical study of transition metal hydrides; comparison of vibrational analysis with experimental data.
Smítalová, Kateřina ; Burda, Jaroslav (advisor) ; Pospíšil, Miroslav (referee)
This thesis compares the results of four theoretical methods to calculate the molecular orbitals against the experimental data. The calculations were carried out in five basis sets, differing mainly in size, upon the set of reference molecules - diatomic hydrides of transition metals. The values, compared to the experiment, include interatomic distance, dissociation energy, anharmonicity and selected vibrational data. Calculations ignoring the theory of relativity provided unusable results. Coupled cluster method was confirmed as the most accurate one and the accuracy of the basis sets was corresponding with their sizes. Results of one of the smaller-sized basis sets were significantly improved with the addition of several polarizing orbitals. Keeping the calculation times significantly shorter, its accuracy was similar to the largest of the used basis sets.
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Computational Study of Organometallic Interactions with Models of DNA/RNA and Proteins Using Tools of Quantum Chemistry and Molecular Mechanics.
Šebesta, Filip ; Burda, Jaroslav (advisor) ; Rulíšek, Lubomír (referee) ; Urban, Ján (referee)
Methods of computational chemistry represent an important tool in development of novel materials or drugs. In this thesis, they are used for investigation of Pt anticancer drugs. Interaction of five hydrated Pt(II) complexes with guanine as a small model of DNA is studied at the DFT level. Several Pt(IV) complexes exhibit less side effects and overcome some resistances of cisplatin, nevertheless they must be reduced to their Pt(II) analogues to obtain anticancer activity due to their high kinetic inertness. Therefore, reduction potentials for eleven Pt(IV) complexes are determined using DFT and post-Hartree-Fock methods. The kinetics of reduction play more important role. Thus, we study reaction mechanisms for reduction of tetraplatin by deoxyguanosine monophosphate and satraplatin by ascorbic acid. In both mechanisms the kinetic model for side reactions is employed since reducing agents occur in different protonation states. From the perspective of interaction of metals with thymine, proton transfer is of great importance. It is shown that the presence of hydrated metal cations - Mg2+ , Zn2+ , Hg2+ leads to a significant decrease of activation barriers for the N3↔O3 proton transfer. The QM/MM umbrella sampling MD method is employed in a study of binding of the hydrated mercury cation to the N3 position in...
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Quantum mechanical study of the electron hoping processes of pigments from photosystems. Simulation of absorption and emission photoelectron spectra.
Cajzl, Radim ; Burda, Jaroslav (advisor) ; Slavíček, Petr (referee)
Title: Quantum mechanical study of the electron hoping processes of pig- ments from photosystems. Simulation of absorption and emission photoelectron spectra. Author: Bc. Radim Cajzl Department: Department of Chemical Physics and Optics Supervisor: prof. RNDr. Ing. Jaroslav Burda, DrSc., Department of Chemical Physics and Optics Abstract: The aim of this thesis is to develop a methodology for simulation of dynamical properties of carotenoids by OMx method combined with surface electron hopping. We use linear conjugated polyenes: ethene, butadiene, hexa- triene up to polyenes with 22 carbon atoms as model systems. First, the spectra are calculated with sufficiently good agreement with the experimental data by both correct order of excited states and small deviation from experimental data. These results are used for electron surface hopping for calculation of mean lifetimes of excited states of studied polyenes. Calculated lifetimes are of the same order as experimental data for butadiene, hexatriene and octatetraene. Calculated lifetimes for poleynes with 20 resp. 22 carbon atoms agree well with chemically analogous carotenoids. Keywords: quantum mechanics, photoelectron spectra, pigments of photosys- tems, elecrton transitions, molecular and electronic dynamics
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Application of chiroptical techniques for exploration of inhomogeneous systems
Jungwirth, Jakub ; Bouř, Petr (advisor) ; Burda, Jaroslav (referee)
Master's Thesis Abstract Jakub Jungwirth Understanding molecular structure of biochemically relevant molecules is of funda- mental interest for these molecules ultimately determine all functions of living organisms. Raman optical activity (ROA) is a chiroptical spectroscopic technique highly sensitive to molecular structure. This thesis presents an introduction to important concepts of ROA and two independent projects aiming to extend the possibilities of ROA, both from the- oretical and experimental points of view. The first project is a conformational analysis of dialanine, an important model peptide. A combined quantum mechanics / molecu- lar dynamics approach was used in spectral simulations and resulted in spectra with an unprecedented agreement with experiment. To obtain information about conformer equi- libria, a decomposition procedure of an experimental spectrum into calculated individual conformer spectra was coded and tested, and proved to be a viable approach. The sec- ond project was an attempt to carry out pioneering ROA measurements of amyloid fibrils, which are difficult to measure due to their inhomogeneous nature (insolubility, birefrin- gence). Within this project, the preparation protocol for such samples was improved. The performance of an all new rotational cuvette was examined and found...
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Studium termodynamických a kinetických parametrů interakcí oligomerních modelů DNK s organokovovými komplexy aktivními v protirakovinné léčbě stanovených metodami kvantové chemie a kombinovanými QM/MM metodami
Matunová, Petra ; Burda, Jaroslav (advisor) ; Sochorová Vokáčová, Zuzana (referee)
It has been proven that platinum and ruthenium complexes are active in anti- cancer treatment. Nowadays, the common chemotherapeutica have a lot of side effects, therefore, drugs with fewer negative impacts are intensively searched for. The first part of the thesis focuses on the study of cis-[Pt(NH3)2Cl2] (cisplatin, DDP) and four platinum potential anticancer agents PtCl2(diaminocyclohexane), PtCl2(NH3)(cyclohexylamine) (JM118), cis-[PtCl2(NH3)(piperidine)] and trans-[PtCl2(NH3)(thiazole)]. Thermodynamic and kinetic parameters of reac- tions of these complexes in semi-hydrated and fully-hydrated form with guanine were studied using QM methods. The reaction with guanine is the key process ini- tiating the anticancer activity. Analyses of electron density were performed at the B3LYP/6-311++G(2df,2pd) level of theory in IEF-PCM model. The second part of the thesis studies the reaction of the so-called 'piano stool' Ru(II) transition metal complex, [Ru(II)(η6 -p-cymene(nalidixic acid)(H2O)]2+ , first with guanine using QM methods and second with ds-DNA model using QM/MM methods. The reaction site, which is described by QM method, is two consecutive guanines and the Ru(II) complex. Analyses of thermodynamic and kinetic parameters, and electron density were performed at the B97D/6-31G* level of theory. All the...
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Computational Study of the TiO2-Catalyzed Synthesis of Acyclonucleosides from Formamide: Implications for the Origin of Life
Mládek, Arnošt ; Burda, Jaroslav (advisor) ; Futera, Zdeněk (referee)
The TiO2-catalyzed synthesis of nucleosides in non-aqueous formamide environ- ment via so-called acyclonucleoside intermediates represents an alternative way for the emergence of nucleic acids monomeric units, which could address the the fundamental problem associated with the formation of a --glycosidic bond between a nucleobase and a sugar moiety. In this computational contribution we present a plausible reaction route for the prebiotic TiO2-catalyzed synthesis of purine C2- and C3-acyclonucleosides in formamide, which does not require photocatalytic or radical chain mechanisms. The maximum computed activation energy along the proposed reaction channel is ≥ 32 kcal·mol≠1 , which is clearly feasible under the experimental conditions of the Saladino synthesis. We show that the rate determining step of the entire reaction path is the deprotonation of the formaldehyde hydrate methylene carbon occurring likely on defective binding sites of an anatase surface. Our calculations thus support the view of Saladino et al. about the catalytic role of the TiO2 surface in the one-pot synthesis of purine acyclonucleosides in heat formamide solution.
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Computational Study of the Properties and Reactivity of Bioinroganic Transition Metal Complexes
Baxová, Katarína ; Burda, Jaroslav (advisor) ; Sochorová Vokáčová, Zuzana (referee)
This work is focused on the reactions of diaqua-tetrakis(μ-acetylato)dirhodium(II,II) with guanine, that shows anti-cancer activities. Guanine can bond to the complex either by oxygen O6 or by nitrogen N7. We studied three possible versions of the system - one that is protonated on guanine, one protonated on the paddle-wheel and a neutral one. For all 6 reactions transition structures were found. For reactants, tranzition states and products we computed the values of electron density in the critical points of bonds, partial atom charges and the interaction energies of the system, guanine and water on the b3lyp/aug-cc- pvdz level. Pseudobasis and pseudopotentials were employed in the case of rhodium atom. For all the reactions thermodynamical properties were computed. Powered by TCPDF (www.tcpdf.org)
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