Suite aux conséquences environnementales provoquées par l’accident nucléaire de Fukushima, il est fondamental d’étudier les mécanismes gouvernant les effets des radionucléides sur la biosphère et ainsi identifier les processus moléculaires responsables du transport et de la déposition d’actinides comme le neptunium et l’uranium. Cependant, les informations concernant l’aspect microscopique des interactions entre actinide et molécules biologiques sont rares. Les données publiées étant majoritairement issue d’études in vivo, la structure des sites de coordination et l’effet de cette complexation sur les fonctions des protéines restent encore à découvrir.La calmoduline (CaM), qui est connue pour son affinité envers les actinides, agit comme un régulateur métabolique du calcium. Cette protéine, qui est présente de manière ubiquitaire dans le corps humain, peut également complexer d’autres métaux comme les actinides. Ainsi, en cas de contamination interne, les actinides complexés à la protéine pourraient l’empêcher de fonctionner correctement et donc avoir des répercussions sur un grand nombre de fonctions vitales pour l’organisme.La complexation du Np et de l’U par la CaM a été étudiée par spectroscopie EXAFS ce qui nous a permis de montrer que les actinides sont incorporés au site de complexation du calcium. Une fois les aspects structuraux et thermodynamiques étudiés, c’est l’impact de cette complexation sur les fonctions de la protéine qui a été étudié.Afin d’évaluer les conséquences de la complexation, une méthode calorimétrique basée sur une réaction enzymatique (Phosphodiesterase) a été développée. Ces expériences réalisées avec des concentrations variables d’actinides (30-500 nM) montrent une diminution de l’activité enzymatique lorsque la concentration d’actinide augmente. Les résultats montrent que le complexe CaM-An agit comme un inhibiteur enzymatique. De plus, on observe qu’à haute concentration en actinide, le complexe CaM-métal agit comme un poison et tue complètement l’activité enzymatique. / Considering the environmental impact of the Fukushima nuclear accident, it is fundamental to study the mechanisms governing the effects of the released radionuclides on the biosphere and thus identify the molecular processes generating the transport and deposition of actinides, such as neptunium and uranium. However, the information about the microscopic aspect of the interaction between actinides and biological molecules (peptides, proteins…) is scarce. The data being mostly reported from a physiological point of view, the structure of the coordination sites remains largely unknown. These microscopic data are indeed essential for the understanding of the interdependency between structural aspect, function and affinity.The Calmodulin (CaM) (abbreviation for CALcium-MODULated proteIN), also known for its affinity towards actinides, acts as a metabolic regulator of calcium. This protein is a Ca carrier, which is present ubiquitously in the human body, may also bind other metals such as actinides. Thus, in case of a contamination, actinides that bind to CaM could avoid the protein to perform properly and lead to repercussions on a large range of vital functions.The complexation of Np and U was studied by EXAFS spectroscopy which showed that actinides were incorporated in a calcium coordination site. Once the thermodynamical and structural aspects studied, the impact of the coordination site distortion on the biological efficiency was analyzed.In order to evaluate these consequences, a calorimetric method based on enzyme kinetics was developed. This experiment, which was conducted with both uranium (50 – 500 nM) and neptunium (30 – 250 nM) showed a decrease of the heat produced by the enzymatic reaction with an increasing concentration of actinides in the medium. Our findings showed that the Calmodulin actinide complex works as an enzymatic inhibitor. Furthermore, at higher neptunium (250 nM) and uranium (500 nM) concentration the metals seem to have a poison-like behavior and “kill” completely the enzymatic activity.

<p>Information and communication technology already has a long history of influence in basically all areas of an enterprise. In recent years though, a major discussion emerged whether information and communication technologies (ICT) offer an additional strategic value for a business.</p><p>The different positions maintain reasonable arguments on both sides. One position is that ICT basically has become a commodity, obtainable by everyone. There would be no strategical nor competitive gain, so extra efforts in ICT would be in vain. Another position is that, although, nowadays ICT is easy to acquire, the organisational skills necessary to manage the change and to profit from a good system are a scarce resource and difficult to reproduce.</p><p>As much as this discussion has been the subject of many academic articles, as little has the research on the views of practitioners emerged. What is their opinion on the strategic relevance of information and communication technology? Do they consider it as merely a necessary commodity, only used to stay competitive, or do they think that there is a competitive advantage to gain in a sophisticated and possibly leading-edge system? Also, a third view is conceivable, in which practitioners regard ICT as just a tool, which serves best by reconsidering the intensity of its use in every new venture.</p><p>In order to get answers to these questions, semi-structured telephone interviews with leading ICT officers were conducted. The outcome gives a broad overview on what practitioners consider as strategically important in ICT systems and what the current view of the academic guild on this question looks like. An analysis on where, how and why the academic- and the business-views overlap or differ from each other, together with an interpretation of the interview results, concludes the work.</p>

Grb2, a modular protein comprised of a central SH2 domain flanked between a N-terminal SH3 (nSH3) domain and a C-terminal SH3 (cSH3) domain, is a component of cell signaling networks involved in the transmission of extracellular information in the form of growth factors and cytokines to downstream targets such as transcription factors within the nucleus. The Grb2-Sos1 interaction is mediated through the combinatorial binding of nSH3 and cSH3 domains of Grb2 to various sites - designated S1, S2, S3, and S4 - containing PXpsiPXR motifs within Sos1. Here, using a diverse array of biophysical techniques, including in particular isothermal titration calorimetry coupled with molecular modeling and semi-empirical analysis, I provide new insights into the Grb2-Sos1 interaction in thermodynamic and structural terms. My data show that Grb2 exists in monomer-dimer equilibrium in solution and that the dissociation of dimer into monomers is entropically-driven. The heat capacity change observed was much smaller than that expected from the rather large molecular surfaces becoming solvent-occluded upon dimerization, implying that monomers undergo conformational rearrangement upon dimerization. 3D structural models suggest strongly that such conformational rearrangement may arise from domain swapping. I further show that the nSH3 domain of Grb2 binds to the S1 site containing the proline-rich consensus motif PXpsiPXR with an affinity that is nearly three-fold greater than that observed for the binding of the cSH3 domain. It is also demonstrated that such differential binding of the nSH3 domain relative to the cSH3 domain is largely due to the requirement of a specific acidic residue, in the RT loop, to engage in the formation of a salt bridge with the arginine residue in the consensus motif PXpsiPXR. The data further reveal that, while binding of both SH3 domains to Sos1 is under enthalpic control, the nSH3 binding suffers from entropic penalty in contrast to entropic gain accompanying the binding of cSH3, implying that the two domains employ differential thermodynamic mechanisms for Sos1 recognition. Additionally, my data reveal that while the nSH3 domain of Grb2 binds with affinities in the physiological range to all four sites S1-S4, the cSH3 domain can only do so at the S1 site. Further scrutiny of these sites yields rationale for the recognition of various PXpsiPXR motifs by the SH3 domains in a discriminate manner. Unlike the PXpsiPXR motifs at S2, S3 and S4 sites, the PXpsiPXR motif at S1 site is flanked at its C-terminus with two additional arginine residues that are absolutely required for high-affinity binding of the cSH3 domain. In contrast, these two additional arginine residues augment the binding of the nSH3 domain to the S1 site but their role is not critical for the recognition of S2, S3 and S4 sites. Molecular modeling is employed to rationalize my new findings in structural terms. Taken together, this thesis provides novel insights into the physicochemical basis of a key protein-protein interaction pertinent to cellular signaling and cancer. My studies bear the potential for the development of novel therapies with less toxicity but more effectiveness for the treatment of disease.

Diamidines are small molecules that generally possess antiparasitic properties and bind preferentially to the minor groove of AT rich DNA. With the goal of getting a better understanding of the thermodynamic driving forces and binding affinities, a series of pentamidine analogs were investigated with various AT rich DNA by ITC, UV-Vis and fluorescence spectroscopic methods. Findings suggest that the substitution of the linker oxygen of pentamidine to a nitrogen slightly improves the binding affinity. All of the investigated compounds are entropically driven at 25 oC with non-alternating AT DNA. Additionally, the increased fluorescence of the nitrogen and sulfur linked analogs will enable future work to be done with fluorescence microscopy to help determine if and where these compounds accumulate in the target organism.

Firms operate in an increasingly complex, unpredictable and fast-moving environment. Understand the business ecosystem in which an innovative company operates is a major leadership stake. Indeed, know how the various possibilities to interact with the actors present in the business ecosystem of an organization are part of the leadership role. In order to survive facing competitive organizations, and to get a sustainable competitive advantage, an innovative organization must be able to combine with various partners on its business ecosystem in order to share knowledge and competencies, and therefor implement open innovation processes may be a key success factor that should not be sidelined. To do so, an oganization must understand innovation to adopt open innovation processes, must also take into account various elements of its business ecosystem to settle competitive dynamics with stakeholders and be able to interact with these different actors, and to finish an innovative organization must be able to set open innovation processes to find a key success factor and perform a sustainable competetive advanage.

Cancer results from the accumulation of genetic mutations in a normal cell that ultimately result in the expression (or overexpression) of oncogenes. The design of drugs having high affinity for specific DNA sequences or structural motifs is vital to gaining a better understanding of gene expression and to the development of new cancer treatments that are based on turning off oncogene expression. This dissertation presents studies of the binding of two ligand families, Berenil (DMZ), and ruthenium polypyridyl complexes (RPCs), to B-DNA and G-quadruplex (G4) DNA. The structureunction relationships for the interaction of these ligand families with DNA were probed by functional group substitution, truncation, or modification of the DMZ amidine groups, and by changing one of the RPC ruthenium ligands from phenanthroline to dipyridophenazine (dppz) or tetraazatetrapyrido-pentacene (tatpp), and lastly by adding a second Ru(Phen)2 core to the tatpp bridging ligand. Removal of one or both amidine groups from DMZ drastically reduces its binding to both B-DNA and G4-DNA. DMZ analogs in which one amidine was replaced by an alkyne group were synthesized with the expectation that the additional π-bonding character of the alkyne group would increase G4 affinity. All of the DMZ alkyne compounds were found to bind preferentially to G4-DNA (over B-DNA) and a few of these compounds demonstrated significant anticancer activity. RPCs with progressively longer ruthenium bound ligands were found to bind with differing affinities to B-DNA and G4-DNA. Monoruthenium RPCs exhibited a preference for binding to B-DNA, while binding the diruthenium RPC to G4-DNA was more complicated exhibiting both tighter and a weaker binding modes in comparison to the B-DNA complex. The diruthenium complex was found to bind more tightly to G4-DNA by approximately 3 kcal mol-1. The binding of small molecules to DNA resulting in the disruption of oncogene transcription represents a powerful approach to the treatment of cancer.

Nonheme iron(II) oxygenases within a common 2-His-1-carboxylate binding motif catalyze a wide range of oxidation reactions involved in biological functions like DNA repair and secondary metabolic processes. The mechanism of O2 activation catalyzed by this enzyme family has been examined by spectroscopic, crystallographic, and computational studies, where it is clear the iron(II) center works with substrate, and cosubstrate to activate O2 by forming a highly oxidizing iron species (iron(IV)-oxo). From a thermodynamic perspective, substrate and/or co-substrate binding organizes the active site for O2 activation, and understanding the interactions among metal, substrate, cosubstrate, and enzyme provides insight into the intramolecular contacts that guide the reaction catalyzed by the enzymes. This dissertation is focused on elucidating the interactions between metal, substrate, and co-substrate in a representative enzyme subfamily of nonheme iron(II) oxygenases, namely the 2-oxoglutarate dependent dioxygenases. Specifically, we investigated the thermodynamic properties of divalent metal ions binding to taurine-dependent dioxygenase (TauD), using Mn2+, Fe2+, and Co2+ ions. Additionally, the thermodynamics associated with substrate and co-substrate binding to Fe·TauD and iron(II)-ethylene forming enzyme (Fe·EFE) were explored using calorimetry and other biophysical techniques.

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