In the search for a sustainable and environmentally friendly energy source, artificial photosynthesis has been proposed  as a promising solution. Using water as a substrate, solar energy can be utilised to store energy in the chemical form of hydrogen fuel. In part of this global scientific effort, this thesis work focuses on enabling molecular dynamics simulations of a particular set of ruthenium centred  water oxidation catalysts. The new catalysts show great success because of a binuclear  reaction  pathway in aqueous solution which makes it very interesting to model and investigate. Utilising quantum  mechanical tools, a set of molecular mechanics force field parameters for Ru-involved bonds, angles, torsions, and partial charges was successfully obtained and examined. The work allows future large scale simulation of water  oxidation and oxygen evolution in order to gain understanding and improve artificial photosynthesis.

Le récepteur à la transferrine (TfR1) est un récepteur très bien conservé au cours de l’évolution qui permet l’entrée du fer (Fe) lié à la transferrine (Fe-Tf) dans les cellules. Une fois internalisé, le fer se détache de la Tf et est exporté dans le cytoplasme tandis que le complexe Tf/TfR1 est recyclé à la membrane plasmique. Le TfR1 est internalisé par un mécanisme clathrine dépendant et peut être soit recyclé à la membrane plasmique par la voie rapide, soit être dirigé vers le compartiment endosomal de recyclage (ERC). Une fois dans l’ERC, le TfR1 peut être soit recyclé à la membrane plasmique par la voie lente, soit être dirigé vers les lysosomes. De nombreuses protéines régulent le routage des protéines internalisées comme les protéines Rab. Il s’agit de petites GTPases impliquées dans les échanges moléculaires entre les différents compartiments cellulaires.Etant la principale voie d’entrée du fer dans la cellule,le TfR1 est exprimé par la plupart des cellules et est surexprimé par les cellules hautement prolifératives dont certaines cellules cancéreuses. Le TfR1 est très étudié comme cible thérapeutique dans le développement de nouvelles stratégies anti-cancéreuses. A24 est un anticorps murin anti-TfR1 dont l’action anti-proliférative et pro-apoptotique ont été démontrées dans plusieurs hémopathies malignes.Nous nous sommes demandés comment la fixation de A24 sur le TfR1 peut produire des effets différents de la fixation de la Fe-Tf. En générant un fragment Fab, nous avons d’abord démontré que le routage du TfR1 dépend de la valence de son ligand. Nous avons ensuite démontré que la fixation monovalente du TfR1 par la Fe-Tf et le Fab induisent son recyclage sans passer par l’ERC. Nous avons également démontré que la fixation divalente du TfR1 par A24 induit son routage depuis l’ERC vers les lysosomes par une voie dépendante de Rab12. / The transferrin receptor (TfR1) is a highly conserved receptor that allows the entry of iron (Fe) linked to transferrin (Fe-Tf) into cells. Once internalized, Fe separates from the Tf and is exported in the cytoplasm whereas the complex Tf/TfR1 is recycled to the cell membrane. TfR1 is internalized by a clathrin mediated endocytosis and can be either recycled to the cell membrane through the rapid pathway or be routed towards the endosomal recycling compartment (ERC). Once in the ERC, the TfR1 can be either recycled to the cell membrane through the slow pathway or be routed towards lysosomes. Many proteins regulates the routing of internalized proteins such as Rab proteins. They are small GTPases involved in molecular exchanges between the different cellular compartments.Being the main mode of entry of iron into cells, TfR1is expressed by almost every cells and is overexpressed by highly proliferative cells including some cancer cells. TfR1 is extensively studied as a therapeutic target for the development of new anti-cancer strategies. A24 is a murine anti-TfR1 whose anti-proliferative and pro-apoptotic roles were demonstrated in several hematological malignancies.We wondered how A24 binding on TfR1 can produce different effects from Fe-Tf binding. By the manufacturing of a Fab fragment, we first demonstrated that TfR1 fate depends on its ligand’s valency. We then demonstrated that the monovalent binding of TfR1 with Fe-Tf or the Fab leads to its recycling without going through the ERC. We also showed that the divalent binding of the TfR1 by A24 leads to its routing from the ERC to lysosomes through a Rab12 dependent pathway.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20201号 / 理博第4286号 / 新制||理||1616(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 北川 宏, 教授 竹腰 清乃理, 教授 島川 祐一 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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Cyano-bridged mixed valence compounds have been known since 1704, but a lot of interest in the bi- and tri-nuclear species has emerged only more recently. The growing interest in these complexes reflects their promise as useful applications in electrochromism, molecular magnetism, and molecular electronics. These properties are activated by the excitation of their metal-to-metal charge transfer (MMCT) transition. We have studied aqueous solutions of the FeHEDTA/Fe(CN)64- system that form intensely colored solutions that absorb strongly in the Vis/NIR region. Typically 1:1 dimeric and 2:1 trimeric complexes are formed. We have used optical spectroscopy and electrochemistry to provide information on reorganizational parameters, electronic coupling between metal centers, molar absorptivities, equilibrium constants, and delocalization factors and have compared results obtained for the binuclear and trinuclear species to results of similar systems either previously studied in our lab or found in the literature.

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Copper (Cu) compounds are widely used as effective agricultural bactericides. Continuous use of these materials has led to Cu accumulation in soil over time. The United States Environmental Protection Agency (US EPA) is concerned about potential Cu contamination in the environment. Improving biocidal efficacy of Cu is an attractive alternative, allowing reduction of Cu amount per application. In this research, we focused on making watersoluble mixed-valence Copper/Silica composite nanogel (CuSiNG) material. The objective is to improve the efficacy of Cu by manipulating Cu valence states. It has been shown in the literature that Cu (0) and Cu (I) states are more potent that Cu (II) states in terms of their antimicrobial efficacy. It is hypothesized that mixed valence Cu will exhibit improved efficacy over Cu (II). A water-soluble mixed valence Cu/silica nanogel (MV-CuSiNG) composite has been synthesized and characterized. Structure, morphology, crystallinity and composition of the MV-CuSiNG material was characterized using High-Resolution Transmission Electron Microscopy (HRTEM), HRTEM Selected Area Electron Diffraction (SAED) and X-ray Photoelectron Spectroscopy (XPS). Amount of Cu loading in MV-CuSiNG composite material was estimated by Atomic Absorption Spectroscopy (AAS). To confirm presence of Cu (I) in the MV-CuSiNG material, Neocuproine (Nc, a Cu (I) specific chelator) assay was used. Antimicrobial efficacy of MVCuSiNG and CuSiNG was evaluated against X.alfalfae, B.subtilis and E.coli using Kocide® 3000 ("Insoluble Cu (II)" compound), Copper sulfate ("Soluble Cu (II)" compound) and Cuprous chloride (Copper (I) compound) as positive controls and silica "seed" particles (without Cu loading) as negative control. Antimicrobial studies included observing bacterial growth inhibition and determining the Minimum Inhibitory Concentration (MIC). Improved antimicrobial efficacy was observed in MV-CuSiNG when compared to CuSiNG and other controls. For the assessment of plant safety of MV-CuSiNG and CuSiNG materials, phytotoxicity studies were conducted using Vinca sp and Hamlin orange under environmental conditions. It was observed that MV-CuSiNG material was safe to plants at commercially used