The oxygen that we breathe and food that we eat are products of the natural photosynthesis. Molecular oxygen is crucial for life on Earth owing to its role in the glycolysis and citric acid pathways that yield in aerobic organisms the energy-rich ATP molecules. Photosynthetic water oxidation, which produces molecular oxygen from water and sunlight, is performed by higher plants, algae and cyanobacteria. Within the molecular structure of a plant cell, photosynthesis is performed by a specific intracellular organelle – the chloroplast. Chloroplasts contain a membrane system, the thylakoid membrane, which comprises lipids, quinones and a very high content of protein complexes. The unique photosynthetic oxidation of water into molecular oxygen, protons and electrons is performed by the Mn4CaO5 cluster in photosystem II (PSII) complex. Understanding the mechanism of water oxidation by Mn4CaO5 cluster is one of the great challenges in science nowadays. When the mechanism of this process is fully understood, artificial photosynthetic systems can be designed that have high efficiencies of solar energy conversion by imitating the fundamental principle of natural system. These systems can be used in future for generation of fuels from sunlight.   In this thesis, the efficiency of water-splitting process in natural photosynthetic preparations was studied by measuring the flash-induced oxygen evolution pattern (FIOP). The overall aim is to achieve a deeper understanding of oxygen evolving mechanism of the Mn4O5Ca cluster via developing a complete kinetic and energetic model of the light-induced redox reactions within PSII complex. On the way to reach this goal, the hydrogen peroxide that is electrochemically generated on surface of Pt-cathode was discovered. The chemical effect of electrochemically produced H2O2 that can interfere in the oxygen evolution pathway or change the observed FIOP data was demonstrated. Therefore, in order to record the clean FIOP data that are further characterized by global fitting program (GFP), H2O2 has to be abolished by catalase addition and by purging the flow buffer of the Joliot-type electrode with nitrogen gas.      After FIOPs free of H2O2-induced effects were achieved, these clean data were then applied to a global fitting approach (GFP) in order to (i) result a comprehensive figure of all S-state decays whose kinetic rates were simultaneously analyzed in a high reliability and consistency, (ii) the dependence of miss parameter on S-state transitions and the oxidation state of tyrosine D (YD) can be tested, (iii) how dependent of all S-state re-combinations (to S1 state) on the various pH/pD values can be also determined in case of using Cyanidioschyzon merolae (C. merolae) thylakoids. Our data support previous suggestions that the S0 → S1 and S1 → S2 transitions involve low or no misses, while high misses occur in the S2 → S3 transition or the S3 → S0 transition. Moreover, the appearance of very slow S2 decay was clearly observed by using the GFP analysis, while there are no evidences of very slow S3 decay were recorded under all circumstances. The unknown electron donor for the very slow S2 decay which can be one of the substances of PSII-protective branch (i.e. cytochrome b559, carotenoid or ChlZ) will be determined in further researches.

Les travaux développés dans cette thèse définissent une approche pour la gestion des impacts des évolutions des profils UML sur les modèles instances. Sur la base d'organisation des diverses connaissances identifiées lors de l'analyse des évolutions d'un profil UML, nous proposons un processus automatisé PEM (Profil Evolution Method) permettant l'identification des évolutions a posteriori sous forme de différences, la reconstruction de ces différences en opérations d'évolution conformes au métamodèle UML, la classification de leur impact et, finalement, l'adaptation des modèles à la nouvelle version du profil UML. L'approche intègre également une activité de formalisation et d'utilisation de patrons d'évolution contenant toutes les informations essentielles employées à chaque étape de notre processus. Ces patrons sont employés dans notre système P²E (Papyrus Profile Evolution) pour guider le concepteur des modèles ou des profils, dans la gestion des évolutions d'un profil UML en évaluant efficacement un sous ensemble suffisant et pertinent d'éléments et de paramètres d'évolution d'un profil UML.Les principales contributions de l'approche résident dans la formalisation d'opérateurs d'évolution à partir du métamodèle UML, la proposition d'une classification des impacts des évolutions sur les modèles instances, la modélisation semi-formelle et explicite d'un catalogue de patron d'évolution contenant les solutions d'adaptation à appliquer sur les modèles instances. / This thesis proposes an approach for the management of UML profiles evolutions and their impacts on instance models. Based on the analysis of standardized UML profiles evolutions, we propose an automated process called PEM (Profile Evolution Method) allowing the evolutions identification a posteriori and their representations as differences; the reconstruction of these differences as evolution operations that are compliant with the UML metamodel; their impacts classification and, finally, the instance models adaptation towards the new UML profile version.The approach includes also an activity of formalization of previous knowledge in the form of evolution patterns. The patterns contain all the essential information used at each step in our P²E system (Papyrus Profile Evolution). They guide the models designer or the profiles designer, in the management of the UML profiles evolution by evaluating efficiently a sufficient subset with pertinent evolving elements and their evolution parameters.In this approach, the major contributions consist in the formalization of evolution operators extracted from the UML metamodel, the proposal of an evolution impacts classification, the specification of a pattern catalog that is semi-formal and explicit for the designers. Finally, the specification of adaptation solutions (to adapt the old model versions to the new UML profile version).