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Lelievre, Chloé. « Formation de liaisons amides par réactions enzymatiques détournées ATP Regeneration System in Chemoenzymatic Amide Bond Formation with Thermophilic CoA Ligase ». Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASF026.
Texte intégralRésumé :
La fonction amide est omniprésente dans les produits naturels et aussi dans de nombreux composés synthétiques comme des principes actifs et des polymères. De nombreuses approches ont été développées pour disposer de méthodes de synthèse efficaces. L'approche la plus courante en chimie conventionnelle est l'acylation d'une amine par un acide carboxylique activé. L'activation nécessite l'utilisation soit d'agents de couplage, résultant en une faible économie d'atomes, soit de catalyseurs couteux parfois utilisés dans des conditions drastiques. Les approches biocatalytiques sont donc des alternatives intéressantes pour des raisons économiques et environnementales. Différentes enzymes peuvent être utilisées comme des hydrolases, des nitrile hydratases et des transglutaminases qui activent l'acide sous forme acyl-enzyme pour favoriser l'addition nucléophile de l'amine. Depuis quelques années, l'intérêt pour les enzymes dépendantes de l'ATP s'est accru.Dans ce projet, nous nous sommes intéressés aux CoA ligases qui catalysent la formation d'acide activé sous forme d'acyl-adenylate puis acyl-thioester. Nous avons ainsi mis en évidence qu'en détournant la réaction par piégeage de l'intermédiaire activé par une amine, nous obtenons l'amide. L'utilisation de CoA ligases thermophiles permet de travailler à une température élevée et ainsi de faciliter l'addition non catalysée de l'amine. Ce système s'affranchit donc de l'utilisation de HSCoA onéreux. Pour un système efficace, nous avons aussi intégré avec succès un système de régénération de l'ATP comprenant une Polyphosphate Kinase 2 (Classe III) et une inorganique pyrophosphatase. L'efficacité de cette cascade a été illustrée par la synthèse chemo-enzymatique à l'échelle du laboratoire du N-méthylbutyrylamide avec un rendement de 77 % avec de faibles quantités en enzyme.L'exploration de la biodiversité par approche génomique basée sur la comparaison de séquence, nous a permis d'identifier plusieurs CoA ligases thermophiles actives sur des substrats ω-amino acides précurseurs de lactames. K6Q029 issue de Thermaerobacter subterraneus a fait l'objet d'études plus approfondies. Elle est notamment active sur des substrats ω-amino acides fonctionnalisés ou non, de chaines carbonées plus ou moins longues, mais aussi sur des acides carboxyliques variés tels que des aromatiques.Grâce à la résolution structurale d'A4YDT1, une CoA ligase promiscuitaire, nous avons identifié, en collaboration avec une équipe de cristallographes de l'université de Groningen (Pays Bas), les résidus impliqués dans sa spécificité de substrats pour les modifier par une approche rationnelle. Des mutants de cette enzyme ont ainsi permis l'obtention de δ-valerolactame et Ɛ-caprolactameThe amide function is widespread in nature and also in many synthetic products such as pharmaceuticals and polymers. Numerous approaches have been developed to provide reliable synthesis methods. The most common approach in conventional chemistry is the acylation of an amine by activated carboxylic acid. Activation requires the use of either coupling reagents resulting in low atom economy, or expensive catalysts sometimes used under drastic conditions. Biocatalytic approaches are therefore interesting alternatives for economic and environmental reasons. Different enzymes can be used such as hydrolases, nitrile hydratases and transglutaminases that activate the acid in acyl-enzyme form to promote the nucleophilic addition of the amine. In recent years, interest in ATP-dependent enzymes has increased.In this project, we focused on CoA ligases that catalyze the formation of activated acid as acyl-adenylate and then acyl-thioester. We have thus demonstrated that by diverting the reaction by scavenging activated intermediate with an amine, we obtain the amide. The use of thermophilic CoA ligases allows us to work at a high temperature and thus facilitate the uncatalyzed addition of the amine. This system therefore dispenses with the use of expensive HSCoA. For a better system, we have also successfully integrated an ATP regeneration system with a Polyphosphate Kinase 2 (Class III) and an inorganic pyrophosphatase. The efficiency of this cascade was illustrated by the lab-scale chemo-enzymatic synthesis of N-methylbutyrylamide in 77 % yield using low enzyme loading.Biodiversity exploration using a genomic approach based on sequence comparison allowed us to identify several thermophilic CoA ligases active towards ω-amino acid substrates. K6Q029 from Thermaerobacter subterraneus was further studied. In particular, this enzyme is active towards ω-amino acid substrates, functionalized or not, with more or less long carbon chains, as well as on various carboxylic acids such as aromatics.Thanks to the structural resolution of A4YDT1, a promiscuous CoA ligase from the literature, we have identified, in collaboration with a team of crystallographers from theUniversity of Groningen (Netherlands), the residues involved in its substrate specificity to modify them by a rational approach. Variants of this enzyme have thus allowed to obtain δ-valerolactam and Ɛ-caprolactam
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Touré, Océane. « Approche biocatalytique pour la synthèse de lactames ». Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASF027.
Texte intégralRésumé :
La biotechnologie est maintenant bien établie dans le paysage de l'industrie chimique. Dans le domaine de la biocatalyse, il existe de nombreux exemples de mise en oeuvre réussie d'étapes enzymatiques dans des procédés de synthèse ou de développement de voies enzymatiques complètes, en particulier dans l'industrie pharmaceutique.Les lactames sont des composés qui se retrouvent dans de nombreux produits naturels et synthétiques, tels que les ingrédients pharmaceutiques actifs (API) et sont des précurseurs dans la chimie des polymères. Pour accéder aux lactames à partir de squelettes simples d'acides omega-aminés, la synthèse nécessite un processus en deux étapes : tout d'abord, l'activation de la fonction acide, puis, l'addition intramoléculaire d'amine nucléophile. Pour les petits lactames (5-7 chaînons), la cyclisation intramoléculaire se produit spontanément une fois l'acide activé.Dans le cadre de nos travaux sur des voies d'accès enzymatiques aux amides, nous avons récemment mis au point une synthèse impliquant une activation par CoA ligases, en absence de CoASH, et utilisant uniquement leur aptitude d'activation de l'acide par adénylation par l'ATP, introduit à seulement 5% molaire grâce à la mise en place d'un système de régénération.Jusqu'à présent, le type de lactames obtenus par biocatalyse est limité aux cycles nus, dépourvus de fonctions. L'objectif du projet est de disposer d'enzymes permettant la synthèse par approche biocatalytique de lactames fonctionnalisés de 5 à 7 chaînons. Pour cela deux types d'approche seront menés :1) Exploration de la biodiversité. Une collection d'enzymes de type CoA ligases, construite par une approche génomique basée sur l'identité de séquences, est disponible au laboratoire. Cette collection, constituée d'environ 250 enzymes, sera criblée sur des substrats précurseurs de lactames d'intérêt. Des enzymes d'adénylation, autres que des CoA ligases ont été identifiées et seront également testées.2) Conception rationnelle. En collaboration avec l'équipe des Pr. Dick Janssen et Dr. Andy-Mark Thunnissen (Université de Groningen, Pays-Bas), les données structurales seront utilisées pour générer des bibliothèques ciblées. Des expériences de docking avec les substrats seront réalisées pour cibler les mutationsBiotechnology is now a well-established part of the chemical industry landscape. In the field of biocatalysis, there are numerous examples of the successful implementation of enzymatic steps in synthesis processes or the development of complete enzymatic pathways, particularly in the pharmaceutical industry.Lactams are compounds found in many natural and synthetic products, such as active pharmaceutical ingredients (APIs), and are precursors in polymer chemistry. To access lactams from simple omega-amino acid backbones, synthesis requires a two-step process: first, activation of the acid function, followed by intramolecular nucleophilic amine addition. For small lactams (5-7 members), intramolecular cyclization occurs spontaneously once the acid has been activated.As part of our work on enzymatic access routes to amides, we recently developed a synthesis involving activation by CoA ligases, in the absence of CoASH, and using only their ability to activate the acid by adenylation with ATP, introduced at only 5 mol% thanks to the implementation of a regeneration system.Until now, the type of lactams obtained by biocatalysis has been limited to bare, functionless rings. The aim of the project is to provide enzymes for the biocatalytic synthesis of 5- to 7-membered functionalized lactams. To achieve this, two approaches will be pursued:1) Exploration of biodiversity. A collection of CoA ligase enzymes, built up using a genomic approach based on sequence identity, is available in the laboratory. This collection, comprising around 250 enzymes, will be screened on lactam precursor substrates of interest. Adenylation enzymes other than CoA ligases have been identified and will also be tested.2) Rational design. In collaboration with the team of Prof. Dick Janssen and Dr. Andy-Mark Thunnissen (University of Groningen, Netherlands), structural data will be used to generate targeted libraries. Substrate docking experiments will be carried out to target mutations
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Menzies, Sam. « Ubiquitin E3 ligase mediated regulation of HMG-CoA Reductase ». Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/273763.
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Loss-of-function genetic screens are a powerful approach to identify the genes involved in biological processes. For nearly a century, forward genetic screens in model organisms have provided enormous insight into many cellular processes. However, the difficulty in generating and recovering bi-allelic mutations in diploid cells severely hindered the performance of forward genetic screens in mammalian cells. The development of a retroviral gene-trap vector to mutagenise the human near-haploid KBM7 cell line transformed forward genetic screens in human cells. The re-purposing of the microbial CRISPR/Cas9 system now offers an effective method to generate gene knockouts in diploid cells. Here, I performed a head-to-head comparison of retroviral gene-trap mutagenesis screens and genome-wide CRISPR knockout screens in KBM7 cells. The two screening approaches were equally effective at identifying genes required for the endoplasmic reticulum (ER)-associated degradation of MHC class I molecules. The ER-resident enzyme HMG-CoA reductase (HMGCR) catalyses the rate-limiting step in the cholesterol biosynthesis pathway and is targeted therapeutically by statins. To maintain cholesterol homeostasis, the expression of HMGCR is tightly regulated by sterols transcriptionally and post-translationally. Sterols induce the association of HMGCR with Insig proteins, which recruit E3 ubiquitin ligase complexes to mediate degradation of HMGCR by the ubiquitin proteasome system. However, the identity of the E3 ligase(s) responsible for HMGCR ubiquitination is controversial. Here, I use a series of genome-wide CRISPR knockout screens using a fluorescently-tagged HMGCR exogenous reporter and an endogenous HMGCR knock-in as an unbiased approach to identify the E3 ligases and any additional components required for HMGCR degradation. The CRISPR screens identified a role for the poorly characterised ERAD E3 ligase RNF145. I found RNF145 to be functionally redundant with gp78, an E3 ligase previously implicated in HMGCR degradation, and the loss of both E3 ligases was required to significantly inhibit the sterol-induced degradation and ubiquitination of HMGCR. A focused E3 ligase CRISPR screen revealed that the combined loss of gp78, RNF145 and Hrd1 was required to completely block the sterol-induced degradation of HMGCR. I present a model to account for this apparent complexity.
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Souza, Clarice de Azevedo. « The Acyl-CoA ligase-like (ACLL) gene family in Arabidopsis and poplar ». Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31283.
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Many genes of unknown function have been annotated in plant genome projects, and many of these may encode undiscovered enzymes. For example, completion of the Arabidopsis thaliana genome sequence revealed large families of phenylpropanoid-like enzymes of unknown functions. Using an in silico similarity search based on the amino-acid sequences of known Arabidopsis genes encoding 4-coumarate:CoA ligase (4CL), I identified nine putative genes as members of the Arabidopsis acyl-CoA ligase-like (ACLL) gene superfamily which encode a plant-specific clade of enzymes closely related to true 4CLs. I also identified all ACLLs in the fully sequenced poplar and rice genomes. Phylogenetic analysis of amino-acid sequences revealed five ACLL clades, each containing at least one ACLL member from each species, suggesting conserved biochemical functions for ACLL enzymes. In four of five clades, most of the ACLL representatives have the PTS1 peroxisomal target sequence, indicating a likely function in that organelle. I established tissue expression profiles and the wound and herbivory responsiveness of Arabidopsis and poplar ACLL genes, and this revealed similar expression patterns for potentially orthologous genes. Finally, I mined publicly available microarray databases for co-expressed Arabidopsis genes, and this data provides clues for potential ACLL biochemical functions. The only non-peroxisomal clade is the one most closely related to true 4CLs and contains a single copy gene in Arabidopsis (ACLL5) and poplar (ACLL13). These genes are flower and anther-preferred in expression, and because of the apparent conservation in sequence and in expression, were chosen for functional analysis. ACLL5 is transiently expressed in tapetum cells just prior to release of microspores from tetrads, suggesting a role in pollen wall and/or sporopollenenin formation. In support of this, an acll5 transposon insertion mutant is male sterile and fails to produce pollen grains. These data suggest that ACLL5 and similar enzymes from other species, produce CoA ester intermediates used in an unknown pathway required for pollen wall formation. In silico co-expression analysis in Arabidopsis has revealed potential other members of this pathway, also conserved across angiosperms. This work highlights the utility of the Arabidopsis model system in the discovery of genes in other plant species with genome sequence information.Science, Faculty of
Botany, Department of
Graduate
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Proctor, Lavinia M. « Pharmacological activity of C3a and C3a receptor ligands / ». [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18423.pdf.
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Rampersad, Marilyn Vena. « The development of N2S2 metal complexes as bidentate ligands for organometallic chemistry ». Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/4913.
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Electronic and steric parameters for square planar NiN2S2 complexes as bidentate, S-donor ligands have been established. According to the (CO) stretching frequencies and associated computed Cotton-Kraihanzel force constants of (NiN2S2)W(CO)4 adducts, a ranking of donor abilities and a comparison with classical bidentate ligands are as follows: Ni(ema)= > { [NiN2S2]0 } > bipy phen > Ph2PCH2CH2PPh2 > Ph2PCH2PPh2. In addition, we have demonstrated that the NiN2S2 ligands are hemilabile as evidenced from CO addition to (NiN2S2)W(CO)4, which is in equilibrium with the resulting (NiN2S2)W(CO)5 species (Keq = 2.8 M-1, G = -1.4 kJ/mole at 50C). Complete NiN2S2 ligand displacement by CO-cleavage of the remaining W-S bond to form W(CO)6 was not observed, indicating that the remaining W-S bond is considerably strengthened upon ring-opening. Several new cluster compounds based on the NiN2S2 ligands bound to CuI, RhI, PdII and W0 are reported. Structural analysis of (NiN2S2)MLn complexes show a unique structural feature defined by the dihedral angle formed by the intersection of NiN2S2/WS2C2 planes; placing the NiN2S2 ligand in closer proximity to one side of the reactive metal center. This unique orientational feature of the NiN2S2 ligands in the series of bimetallic compounds contrasts with classical diphosphine or diimine ligands. The "hinge angle" ranges in value from 136 as in the (Ni-1*)W(CO)4 to 101 in the (Ni-1)Pd(CH3)(Cl) complexes. The rigidity of the SR hinge of the nickeldithiolate ligands suggests that they might be suitable for stereochemical and regioselective substrate addition to catalytically active metals such as RhI and PdII.. The structural as well as functional similarities of the acetyl CoA synthase enzyme (ACS) and a palladium-metal based industrial type catalyst led to the preparation of a [(Ni-1)Pd(CH3)]+ bimetallic complex. This complex facilitates CO and ethylene copolymerization to produce polyketone similar to conventional (diphosphine)Pd(X)2 catalysts. However, the diphosphine ligands produce more efficient catalysts as the electron-rich character of the NiN2S2 ligand favors the resting state of the catalyst, [(Ni-1)Pd(C(O)CH3)(CO)]+, over the reactive form (Ni-1)Pd(C(O)CH3)(2-C2H4)]+. An exploratory investigation with the Ni-Pd heterobimetallic showed that this complex also facilitated the C-S coupling reaction to form a thioester similar to the ACS enzyme.
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Prado, Rogilene Aparecida. « Clonagem gênica e caracterização de uma enzima tipoluciferase de coleópteros não bioluminescentes e sua relação com a origem da atividade luminescente ». Universidade Federal de São Carlos, 2012. https://repositorio.ufscar.br/handle/ufscar/5399.
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Previous issue date: 2012-03-06Universidade Federal de Minas Gerais
Bioluminescence in beetles is dependent on luciferase which evolved from AMP/CoA ligases. The cDNA of a luciferase-like enzime was cloned from the Malpighian tubules of Zophobas morio mealworm (Coleoptera: Tenebrionidae). The gene product of this cDNA displays weak luminescence and it is composed of 528 aminoacids residues with N-terminal and C-terminal sequences signal addressed to smooth endoplasmic reticulum membrane. Although having a low identity (26-32%) with beetle luciferases, this enzyme is a reasonable protoluciferase model to investigate the origin and evolution of beetle luciferases. The luciferin binding site is higly conserved among the beetle luciferases. However, in this protoluciferase of Z. morio, most of these residues of this motif are substituted by others. Using a site-directed mutagenesis survey some of aminoacids residues of this protoluciferase, which are located at correspondent luciferin binding site of luciferases, were replaced by the conserved residues of beetle luciferases. Most of the substitutions had negative effect on the luminescent activity, however, the substitution I327T, which is located in a β-hairpin motif close to the luciferin binding site, improved the luminescence activity. Such substitution indicates the importance of this motif for luciferase activity and indicates a possible route for the evolution of bioluminescence function of beetle luciferase. Since this enzyme is located in the Malpighian tubules, which are involved in excretion and metabolization of carboxylic substrates, this enzyme could be involved to excretion the some type of chemical compound. Regardless of the function the results show that the potential for bioluminescent activity is older and probably arose before the divergences of the Coleoptera bioluminescent families.
A bioluminescência em coleópteros é dependente das luciferases, enzimas que evoluíram das AMP-CoA ligases. O cDNA de uma enzima tipo-luciferase foi clonado dos túbulos de Malphighi de larvas de Zophobas morio (Coleoptera: Tenebrionidae). O produto gênico deste cDNA mostra naturalmente uma fraca luminescência na presença de MgATP e luciferina e possui 528 aminoácidos com sequências sinal na região N-terminal e C-terminal endereçadas a membrana do retículo endoplasmático liso. Apesar de ter uma baixa identidade (26-32%) com as luciferases de vaga-lumes, esta enzima é um modelo apropriado de protoluciferase para investigar a origem e evolução das luciferases de besouros. O sítio de ligação da luciferina é altamente conservado entre todas as luciferases de besouros; na protoluciferase de Z. morio porém, a maioria dos resíduos desta região é substituído por outros. Utilizando-se a técnica de mutagênese sitio-dirigida, alguns resíduos de aminoácidos desta protoluciferase, que são localizados na correspondente região do sítio ativo das luciferases, foram substituídos pelos resíduos conservados das luciferases. A maioria das substituições teve um efeito negativo sobre a atividade luminescente. Porém, a substituição I327T, cujo resíduo é localizado em um motivo grampo β, perto do sítio de ligação da luciferina, aumentou sua atividade luminescente. Tal substituição mostra a importância deste motivo para a atividade luciferásica e indica uma possível rota de evolução das luciferases de coleópteros. Uma vez que esta enzima foi extraída dos túbulos de Malpighi, é possível que esteja envolvida com a excreção de algum composto químico. Independente de sua função, os resultados do presente trabalho sugerem que o potencial para atividade bioluminescente é bem antigo nas ligases e provavelmente evoluíram antes da divergência das famílias de coleópteros bioluminescentes.
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Wendt, Kerstin Sybille. « Zwei Untereinheiten aus Proteinkomplexen die Kristallstruktur der APC10-Untereinheit des humanen Anaphase-promoting-Complex und die Kristallstruktur der Carboxytransferase-Untereinheit der Glutaconyl-CoA-Decarboxylase aus Acidaminococcus fermentans / ». [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965479730.
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Studart-Guimarães, Claudia Rodriguez. « Functional analysis of the role of succinyl CoA ligase in the photosynthetic metabolism of tomato ». [S.l.] : [s.n.], 2006. http://www.diss.fu-berlin.de/2006/409/index.html.
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Tron, Cecile M. V. « Structural and functional studies of biotin protein ligase and its bacterial substrate acetyl-CoA carboxylase ». Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/14582.
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Biotin protein ligase (BPL) catalyzes the formation of biotinyl-5’-AMP from biotin and ATP and the succeeding biotinylation of the biotin carboxyl carrier protein (BCCP). The genes encoding the BPL from the hyperthermophyle Aquifex aeolicus were overexpressed in E. coli and the recombinant protein AaBPL was purified to homogeneity. AaBPL was purified to homogeneity. AaBPL was proven to be catalytically active and to biotinylate specifically the C-terminal biotinyl domain of BCCP (BCCPΔ67). It was determined by isothermal titration calorimetry experiments that in the class I AaBPL, the presence of biotin is not required for ATP binding in absence of Mg2+ ions and the binding of biotin and ATP has been determined to occur via a random but cooperative process. In the second step of the enzymatic reaction, BPL has been suggested to form a BPL:BCCP complex. This complex was characterized in A. aeolicus by chemical cross-linking and mutational studies have identified a salt bridge between AaBPL and BCCPΔ67 which is important for heterodimerisation. The structures at 2.4 Å resolution of AaBPL in the apo-form and in complex with biotin and ATP were determined. These are the first crystal structures of a BPL complex with biotin and ATP and also of an ATP-bound BPL. The adenylate binding loop is ordered in the structure of apo-AaBPL and the ATP binding pocket is well defined. The solvent-exposed β- and γ-phosphates of ATP are located in the inter-subunit cavity formed by the N- and C-terminal domains. The Arg40 residue from the conserved GXGRXG motif is shown to interact with the carboxyl group of biotin and to stabilise the α- and β- phosphates of the nucleotide.
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Lamm, Teresa Renée. « Redox modulation of acyl-CoA dehydrogenases (ACDs) and their ligands in several ACD-analog systems / ». Diss., ON-CAMPUS Access For University of Minnesota, Twin Cities Click on "Connect to Digital Dissertations", 2001. http://www.lib.umn.edu/articles/proquest.phtml.
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Micheletto, Mariana Chaves. « Clorocatecol 1,2-dioxigenase e Proteína Ligante de Acil-CoA : caracterização estrutural e interações com ligantes ». Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-01122016-092008/.
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Neste trabalho foi utilizado um esquema multi-técnicas para estudar a base de interações moleculares protagonizadas por duas proteínas que possuem funções biológicas completamente distintas. A primeira delas, clorocatecol 1,2-dioxigenase (Pp 1,2-CCD), tem um apelo biotecnológico para área ambiental devido a sua capacidade de catalisar a degradação do composto clorocatecol, um intermediário comum no final da decomposição de diversos hidrocarbonetos aromáticos policíclicos. Essa característica pode promover a descontaminação de solos e águas poluídos revelando um grande potencial para aplicações em mecanismos de biorremediação. Além disso, a presença de moléculas anfipáticas junto à interface de ligação dos monômeros da CCD levantou a questão em relação à capacidade dessa família de enzimas de se ligar a membranas biológicas. Esse tipo de informação amplia o conhecimento acerca de mecanismos básicos de ação da enzima, aumentando a possibilidade de parceiros de interação, podendo levar a outras formas de controle da atividade biológica para uso em aplicações biotecnológicas como desenvolvimento de biossensores. O estudo dessa enzima está, portanto, voltado para a compreensão de suas interações com miméticos de membrana e a tentativas de imobilização da proteína nestas estruturas. Para isto, fazemos uso de técnicas biofísicas como dicroísmo circular, caloria diferencial de varredura e espectroscopias ópticas, e biomoleculares como desenvolvimento de oligonucleotídeos, reações de cadeia polimerase e análise de restrição. A outra vertente desta dissertação, tem como foco de estudo a proteína ligante de acil-CoA de Cryptococcus neoformans (CnACBP) clonada pela primeira vez em nosso laboratório. Homólogos de ACBP foram encontrados em todos os organismos distribuídos nos quatro reinos eucariotos, com alta similaridade sequencial (~48%). A sua presença ao longo dos reinos e seu envolvimento em diversos mecanismos metabólicos essenciais relacionados ao éster acil-CoA levaram à conclusão de que se trata de uma housekeeping protein, e não uma proteína específica, confinada a um tipo especializado de célula. Este trabalho traz uma caracterização inicial da CnACBP que busca esclarecer questões ainda em aberto e também aprofundar o conhecimento ainda muito vago de como cargas e a presença do ligante podem influenciar estrutura, estabilidade e função através de técnicas termodinâmicas e espectroscópicas antes de um aprofundamento de seu papel no interior da célula e interações com outras proteínas.In this study, we used a multi technique approach to understand the basic molecular interactions of two proteins that have quite different biological functions. The first, chlorocatechol 1,2- dioxygenase (Pp 1,2-CCD), has an environmental appeal due to it ability to catalyze the degradation of chlorocatechol, a common intermediate in the end of the decomposition of many polycyclic aromatic hydrocarbons. This characteristic of decontaminating polluted soils and waters suggest a great potential for applications in bioremediation mechanisms. Moreover, the presence of amphipathic molecules at the interface of the CCD monomers raised issues related to the ability of this enzyme family of binding to biological membranes. Such information broadens the knowledge of the basic mechanisms of enzyme action, increasing the possibility of interaction partners and may lead to other forms of control of the biological activity for use in biotechnological applications, such as biosensors development. The study of this enzyme is therefore, aimed at understanding their interactions with mimetic membrane and immobilization attempts of the protein in these structures. For this purpose, we make use of biophysical techniques such as circular dichroism, differential scanning calorimetry and optical spectroscopies and biomolecular techniques, such as development of primers, polymerase chain reaction and restriction analysis. The other aspect of this dissertation is focused on the study of acyl-CoA binding protein of Cryptococcus neoformans (CnACBP) cloned for first time in our laboratory. Homologues of ACBP were found in all organisms distributed in the four kingdoms of eukaryotes, with high sequence similarity (~ 48%). Its widespread presence and their involvement in several key metabolic pathways related to the acyl-CoA ester led to the conclusion that ACBP is a housekeeping protein and not a specific protein contained a specialized cell type. Here we present an initial characterization of CnACBP that seeks to relevant issues regarding the proteins function. Our goal was to increase the still vague knowledge on how electrical charges and the presence of the binding partner may influence the structure, stability and function through thermodynamic and spectroscopic techniques. This is an initial step toward the full understanding of the role of protein in the cell.
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Allina, Sandra Mary. « Phenylpropanoid metabolism in poplar, characterization of the 4-coumarate:CoA ligase gene family and a putative hydroxycinnamoyl-CoA thioesterase ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ38847.pdf.
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Hung, Laurence. « Etude d’un procédé d’extraction en milieu CO2 supercritique de l’uranium à partir de minerais ». Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4310.
Texte intégralRésumé :
La recherche de nouveaux procédés propres et durables pour extraire l’uranium des minerais en alternative à l’extraction liquide-liquide conduit à s’intéresser aux procédés d’extraction en milieu CO2 supercritique. L’objectif de ce travail est donc d’étudier la faisabilité de l’extraction de l’uranium des minerais en milieu CO2 supercritique, à l’aide de molécules extractantes adaptées. Dans un premier temps, des mesures de solubilité des ligands sélectionnés pour cette étude préliminaire, trioctylamine et PC88A (acide 2-éthylhexyl 2-éthylhexyl phosphonique), et des complexes métalliques que ces molécules forment avec le molybdène utilisé comme simulant inactif de l’uranium et l’uranium, ont été effectuées en milieu CO2 supercritique. L’étude du procédé d’extraction dynamique en milieu CO2 supercritique a ensuite été réalisée en inactif, d’abord sur une solution aqueuse sulfurique de molybdène puis sur des poudres d’oxydes de molybdène. Les étapes de solubilisation du complexe ligand-Mo en CO2 supercritique et d’attaque du solide par le système extractant (ligand/acide/oxydant) sont les étapes limitantes à contrôler. Le choix d’un système extractant adapté devient alors primordial. En tenant compte des résultats obtenus en inactif (Mo), des essais d’extraction sur minerai d’uranium à partir de PC88A en milieu CO2 supercritique ont finalement été réalisés en présence d’acide sulfurique et d’oxyde de manganèse. Le procédé a ainsi pu être validé, plus de 60 % de l’uranium du minerai a été collecté en sortie de montage. Toutefois, l’effet de certains paramètres opératoires reste à étudier ainsi que la synthèse/sélection de nouvelles molécules extractantes cibléesThe research of clean and sustainable new processes to extract uranium from ores as an alternative to solvent extraction leads one to consider extraction processes using supercritical carbon dioxide. The aim of this work is to study the extraction feasibility of uranium ores by supercritical CO2, using suitable ligands. First, solubility measurements of selected ligands, trioctylamine and PC88A (2-ethylhexyl 2-ethylhexylphosphonic acid), and metal complexes formed between these ligands and molybdenum (uranium surrogate) or uranium, are performed in supercritical CO2. Supercritical CO2 extractions are then carried out on sulfuric aqueous solutions containing molybdenum and on molybdenum oxides powder. Solubilization of the extractant system (ligand/acid/oxidant) and solid leaching are the key steps which need to be controlled. Well-suited extractant system selection is therefore fundamental. The hypothetical mechanisms, describing supercritical carbon dioxide extraction, seem to be quite different from those usually observed in solvent extraction, especially in terms of selectivity and formed complex structure. Based on the results obtained with molybdenum, extraction trials on uranium ores were then conducted using PC88A in supercritical carbon dioxide with sulfuric acid and manganese oxide. More than 60% of uranium was recovered, which confirmed this new process feasibility. However, the influence of some operating parameters and the synthesis/selection of new suitable ligands remain to be further studied
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Stromberger, Carmen [Verfasser]. « Screen for abnormal mitochondrial phenotypes in mouse embryonic stem cells identifies a model for succinyl-CoA ligase deficiency and mtDNA depletion / Carmen Stromberger ». Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2015. http://d-nb.info/1079840907/34.
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Jin, Guanghua. « Coordination chemistry and catalysis at iron : from non-innocent ligands to CO2 transformation ». Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30155/document.
Texte intégralRésumé :
L'utilisation du fer en chimie de coordination et en catalyse suscite un intérêt croissant de par son abondance et sa faible toxicité. Dans le premier chapitre, une étude bibliographique présente deux domaines d'applications du fer : i) l'utilisation de complexes de fer comportant des ligands " non innocent " pour différentes applications en catalyse, et ii) l'utilisation de complexes de fer pour des transformations stœchiométriques et catalytiques du CO2. Dans le chapitre 2, la synthèse et la caractérisation de complexes de fer portant un ligand coopératif non-innocent sont présentées. Le composé hautement réactif [Fe(N(TMS)2)2] a été choisi comme précurseur pour l'étude de la coordination du ligand bis(picolyl)phosphine dans des conditions douces. Une famille de complexes mono- et di-nucléaires de fer a été isolée et le comportement " non-innocent " du ligand a été mis en évidence. La combinaison de plusieurs techniques : diffraction des rayons X, RMN (en solution et à l'état solide), RPE, Mössbauer et spectroscopie infrarouge a permis de complètement caractériser à la fois les complexes diamagnétiques mais aussi paramagnétiques. Le chapitre 3 se concentre sur la transformation de CO2 par un système catalytique efficace au fer. Les complexes dihydrure de fer [Fe(H)2(diphosphine)2] catalysent la fonctionnalisation réductrice du CO2 dans des conditions douces. Dans ce système, la première étape concerne la réduction catalytique du CO2 par des hydroboranes donnant un composé bis(boryl)acetal. Via une stratégie " un pot, deux étapes " l'intermédiaire acétal est ensuite utilisé comme source de méthylène et est fonctionnalisé pour donner une série de composés organiques contenant non seulement des liaisons C-N mais aussi des liaisons C-O, C-S et C-C avec de bons à très bons rendementsThere is an increasing interest in the use of iron in coordination chemistry and catalysis because it is an earth abundant metal which exhibits a low toxicity. The first chapter is a bibliographic study concerning two areas of applications for iron: the combination of iron with non-innocent ligands leading to highly active catalysts, and the use of iron complexes for CO2 transformations at the stoichiometric and catalytic levels. In chapter 2, the synthesis and characterization of iron complexes bearing a cooperative non-innocent ligand are presented. The highly reactive compound [Fe(N(TMS)2)2] has been chosen as a precursor for the study of the coordination of the bis(picolyl)phosphine ligand under mild conditions. As a result, a family of mono- and di-meric iron complexes has been isolated and the non-innocent behavior of the ligand has been observed. The combination of several techniques: X-ray diffraction, NMR (in solution and in the solid state), EPR, Mössbauer and infrared spectroscopy allows to clearly characterize both diamagnetic and paramagnetic complexes. Chapter 3 focuses on the transformation of CO2 catalyzed by an efficient iron-based system. In this system, iron hydride complexes [Fe(H)2(diphosphine)2] have been chosen to catalyze the reductive functionalization of CO2 through a one-pot two steps strategy under mild conditions. The first step concerns the iron-catalyzed reduction of CO2 by hydroboranes affording a bis(boryl)acetal compound. This intermediate is then used as a source of methylene in functionalization reactions, leading to a series of organic compounds containing not only C-N but also C-O, C-S, and C-C bonds in good yields
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Ohleier, Alexia. « Nickel mediated negishi and oxidative couplings ». Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30074/document.
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Ce projet de recherche porte sur la formation de nouvelles liaisons C-C et la production de produits chimiques valorisables grâce à l'utilisation de complexes de nickel chélatés. La première partie de cette thèse est dédiée à des complexes bis-phosphines de nickel employés comme catalyseurs pour le couplage croisé de Negishi. Le précatalyseur [(dcpp)Ni(n2-toluene)] (dcpp = 1,3 bis(dicyclohexylphosphino)propane) permet de coupler efficacement des chloro-arènes avec des organozinciques en utilisant de faibles charges catalytiques (0,2 mol% - 0,1 mol%) et des conditions douces (THF, 60 °C). Une étude mécanistique fondée sur des réactions stœchiométriques et des calculs DFT prouve la présence d'intermédiaires Ni(0)/Ni(II) au cours de la catalyse et exclut tout passage par un mécanisme de type Ni(I)/Ni(III). La seconde partie de ce travail porte sur le couplage oxydant entre l'éthylène et le CO2 sur des complexes de nickel chélatés par des bis-phosphines ou des bis-NHC. Une étude cinétique de l'équilibre entre [(dcpp)Ni(C2H4)] et [(dcpp)nickelalactone] a été réalisée. Le complexe [(dcpp)nickelalactone] peut ensuite être réduit et fonctionnalisé en dérivé du propanol en présence de pinacolborane. Des études mécanistiques et catalytiques préliminaires ont eté menées. De plus, de nouvelles méthodologies de synthèses ont été développées afin d'obtenir les premiers complexes [(bis-NHC)Ni(C2H4)] et [(bis-NHC)nickelalactone]The aim of this research project is to promote the formation of new C-C bonds and the production of valuable chemicals by using chelated nickel complexes. The first part of this thesis is dedicated to [nickel(bis-phosphine)] complexes employed as catalysts for Negishi cross coupling reactions. Designed Ni(0) precatalyst [(dcpp)Ni(n2-toluene)] (dcpp = 1,3-bis(dicyclohexylphosphino)propane) promotes efficiently the Negishi cross coupling between aryl chlorides and phenylzinc chloride derivatives at low catalyst loadings (down to 0.2 mol% - 1 mol%) under mild conditions (THF, 60°C). Mechanistic investigations relying on stoichiometric reactions and DFT calculations prove the involvement of Ni(0)/Ni(II) intermediates rather than Ni(I)/Ni(III) species during the catalysis. The second part of this work deals with the oxidative coupling between ethylene and CO2 at bis-phosphine and bis-NHC chelated nickel complexes for the production of value-added chemicals. The equilibrium between [(dcpp)Ni(C2H4)] and [(dcpp)nickelalactone] has been investigated by kinetic studies. The subsequent cleavage of [(dcpp) nickelalactone] by pinacolborane leads to its reductive functionalization into a propanol derivative. Preliminary mechanistic and catalytic investigations have been undertaken. Moreover, new methodologies are provided for the synthesis of the first [(bis-NHC)Ni(C2H4)] and [(bis-NHC)nickelalactone] complexes
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Kreft, Gabriel Luiz. « Interação e clivagem de DNA por complexos de Co2+ com ligantes tripodais n-doadores ». reponame:Repositório Institucional da UFSC, 2014. https://repositorio.ufsc.br/xmlui/handle/123456789/132964.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Praduação em Química, Florianópolis, 2014Made available in DSpace on 2015-05-19T04:05:41Z (GMT). No. of bitstreams: 1 333308.pdf: 2483116 bytes, checksum: 9bc13a8ec635182c0a3f52919af77c62 (MD5) Previous issue date: 2014
Muitos estudos têm sido realizados com o ácido desoxirribonucleico interagindo com pequenas moléculas, entre estas os compostos de coordenação que podem atuar como miméticos de enzimas presentes nos organismos vivos. Com essa finalidade, foram avaliados a clivagem e a interação do DNA com uma série de cinco compostos de Co2+ com ligantes N-doadores tetradentados: Co(TPA)Cl]ClO4, [Co(6-MeTPA)Cl]ClO4, [Co(6-Me2TPA)Cl]ClO4, [Co(BPQA)Cl]ClO4, e [Co(BQPA)Cl]ClO4. O DNA plasmidial pBSK II foi utilizado como modelo na técnica de eletroforese em gel de agarose. Foram realizados ensaios variando a concentração dos complexos para avaliar o efeito na atividade de clivagem, ensaios de cinética para comparar atividade com outros complexos da literatura, ensaios com inibidores de espécies reativas de oxigênio e ensaios com atmosfera de argônio com o intuito de verificar se o mecanismo de clivagem é hidrolítico ou oxidativo, ensaio com o ligante de sulco menor: distamicina e o ligante de sulco maior: verde de metila com o proposito de verificar a dependência da ligação com os sulcos e ensaios na presença de perclorato de lítio para verificar o efeito das interações eletrostáticas. Os cinco complexos são ativos frente a clivagem do DNA plasmidial, em concentrações na ordem de micromolar. Os complexos devem atuar por um mecanismo hidrolítico e são muito sensíveis ao efeito da força iônica. Nos ensaios cinéticos foram obtidos valores de kcat entre 0,98 h-1 a 6,02h-1, para pH 7,0 e valores de kcat entre 1,99 h-1 e 16,8 h-1 para pH 9,0, correspondendo a valores que aumentam a velocidade de reação na ordem de 108 a 109 comparados à hidrólise não catalisada do DNA. Também foram realizados ensaios com eletroforese com gel de poliacrilamida de alta resolução, como modelo utilizado foi uma sequência de 49 nucleotídeos. Foi verificado que os compostos [Co(6-MeTPA)Cl] e [Co(BPQA)Cl] clivam o DNA em todos os nucleotídeos formando produtos com terminal 3´-PO32-, sem gerar produtos típicos de mecanismos oxidativos.
Abstract: Many studies have been conducted with the deoxyribonucleic acid interacting with small molecules, within them coordination compounds which may act as enzyme mimics in living organisms.For this purpose cleavage and interaction with DNA were evaluated for a series of five Co(II) compounds with tetradentate N-donor ligands: [Co(TPA)Cl]+, [Co(6-MeTPA)Cl]+, [Co(6-Me2TPA)Cl]+ [Co(BPQA)Cl]+ and [Co(BQPA)Cl]+. The plasmid DNA pBSK II was used as substrate in gel electrophoresis assays were performed varying the concentration of the complex, kinetic assays to assess DNA cleavage, trials with inhibitors of reactive oxygen species, trials with argon, assays with DNA groove binders and assays in the presence of lithium perchlorate to verify the effect of electrostatic interactions. The five complexes are active against the cleavage of plasmid DNA at concentrations on the order of micromolar.Complexes may act by a hydrolytic mechanism, are very sensitive to ionic strength effect. In kinetic experiments were obtained values of kcatbetween0,98 h-1to 6,02 h-1for pH 7.0 and values of kcat between 1,99 h-1to 16,8 h-1for pH9.0, corresponding to values that increase the reaction rate about108 to 109compared to spontaneous hydrolysis of DNA. Assays using high resolution polyacrylamide gel electrophoresis were made, the model used was a sequence of 49 nucleotides, it has been found that the compounds [Co (6-MeTPA) Cl] and [Co (BPQA) Cl] cleave DNA at all nucleotides forming products with 3'-PO32- termini without generating products of oxidative mechanism.
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Petriccone, Massimo. « Dendrimères spécifiquement fonctionnalisés pour la catalyse en médias spéciaux ». Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSES048.
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La recherche présentée constitue une exploration approfondie des dendrimères de phosphorhydrazone (PPH), se plongeant dans leur synthèse, leur fonctionnalisation et leurs applications catalytiques. Le processus de synthèse, amorcé à partir d'atomes de phosphore chlorés dans le noyau, évolue par substitution avec du 4-hydroxybenzaldéhyde, aboutissant finalement à la génération de dendrimères par condensation avec MMHP(S)Cl2, suivant une séquence réactionnelle méticuleuse en deux étapes. Afin de permettre l'introduction ultérieure de métaux, divers dérivés phénoliques ont été synthétisés, accompagnés d'une molécule modèle émulant l'activité de l'iminophosphine et résolvant les problématiques d'oxydation du phosphore. La synthèse de phénols bidentés est détaillée, mettant en lumière les défis rencontrés et les optimisations réalisées, en particulier en termes de scalabilité des procédures. L'exploration s'étend également à la modification des surfaces des dendrimères pour améliorer leur solubilité, avec un accent spécifique sur l'intégration de ligands perfluorés. Malgré des défis liés au rendement global, des voies synthétiques alternatives ont été envisagées, conduisant à la synthèse réussie de phénols fonctionnalisés en position para avec des chaînes alkylpolyfluorées de longueurs variées. La caractérisation des dendrimères PPH débute par la préparation du dichlorure de (1-méthylhydrazinyl)phosphonothioïque (MMHP(S)Cl2), suivi de la synthèse de molécules modèles simulant les surfaces des dendrimères PPH et progressant vers des générations de dendrimères plus élevées. Les caractéristiques distinctives des dendrimères PPH, y compris leur identification par RMN du phosphore-31, sont mises en évidence, avec un accent particulier sur le défi de la scalabilité, surmonté avec succès. La recherche se penche ensuite sur la fonctionnalisation précise des dendrimères PPH avec des substituants phénoliques préalablement synthétisés. L'objectif était de minimiser la substitution di-symétrique lors de la di-fonctionnalisation précise de la fonction P(S)Cl2. La synthèse du catalyseur implique des ligands avec complexation métallique pour assurer la stabilité. Les dendrimères PPH di-fonctionnalisés de manière précise et stochastique ont été avec succès produits à l'échelle du gramme. Enfin, la recherche aborde l'activité catalytique des dendrimères dans diverses réactions de couplage, tant dans des solvants organiques que non conventionnels. Les réactions de couplage croisé de Stille, de Heck et de Suzuki ont été explorées. Le catalyseur dendrimérique a montré une activité accrue dans la réaction de couplage croisé de Stille, mettant en évidence un effet dendritique de génération positif et multivalent. Malgré son insolubilité dans le scCO2, le catalyseur a montré une activité pour la réaction de couplage croisé de Stille dans des conditions hétérogènes, soulignant un effet dendritique de génération positif. De plus, le catalyseur dendrimérique a montré une activité pour la réaction de couplage croisé de Heck dans un système biphasique fluoreux/organique. L'étude adresse également les défis liés à la récupération du catalyseur dans des solvants organiques et non conventionnels. Les comparaisons entre les dendrimères difonctionnalisés de manière précise et stochastique mettent en avant les effets positifs de la multivalence et de la génération dendritique dans des réactions spécifiques. Notamment, une activité plus élevée des dendrimères difonctionnalisés de manière précise de la génération 1 à 3 par rapport aux homologues difonctionnalisés de manière stochastique a été démontrée dans la réaction de couplage croisé de Stille. En résumé, cette recherche offre une exploration approfondie de la synthèse, de la fonctionnalisation et des applications catalytiques des dendrimères, suggérant des perspectives d'amélioration pour des processus catalytiques durablesThe presented research represents a comprehensive exploration of phosphorhydrazone (PPH) dendrimers, delving into their synthesis, functionalization, and catalytic applications, with a specific focus on para-substituted phenols for surface functionalization. The synthesis process entails a meticulous two-step reaction sequence, initiating from chlorinated phosphorus atoms in the core and progressing through substitution with 4-hydroxybenzaldehyde, ultimately culminating in dendrimer generation through condensation with MMHP(S)Cl2. To enable subsequent metal introduction were synthesized different phenolic derivates, alongside a model molecule designed to emulate iminophosphine reactivity while addressing phosphine oxidation concerns. The synthesis of bidentate phenols was described in detail, emphasizing the challenges faced and optimizations made, with a particular focus on the scalability of the procedures. The research also explores the modification of dendrimer surfaces to enhance solubility, with a specific emphasis on integrating perfluorinated ligands. Despite challenges in overall yield, alternative synthetic pathways were considered, resulting in the successful synthesis of phenols functionalized in the para position with alkylpolyfluorinated chains of varying lengths. Moving on to the characterization of PPH dendrimers, the study begins with the preparation of (1-methylhydrazineyl)phosphonothioic dichloride (MMHP(S)Cl2). Model molecules were synthesized to simulate PPH dendrimer surfaces, progressing to higher dendrimer generations. Distinctive features of PPH dendrimers, including their identification through 31P-NMR, were highlighted. A significant challenge in this phase involved ensuring the scalability of PPH dendrimer synthesis, which was successfully overcome. The research then shifts its focus to the precise functionalization of PPH dendrimers with previously synthesized phenolic substituents. The objective was to minimize di-symmetric substitution during the precise di-functionalization of the P(S)Cl2 function. Catalyst synthesis involved ligands with metal complexation for stability. Both precisely and stochastically substituted PPH dendrimers were successfully scaled up to the gram scale. In the final segment, the research delves into the catalytic activity of dendrimeric catalysts in various coupling reactions, both in organic and non-conventional solvents. Stille cross-coupling, Heck cross-coupling, and Suzuki coupling reactions were explored. The dendrimeric catalyst exhibited heightened activity in the Stille cross-coupling, showcasing a positive multivalence and generation dendritic effect. Despite insolubility in scCO2, the catalyst demonstrated activity for the Stille cross-coupling in heterogeneous conditions, emphasizing a positive generation dendritic effect. Additionally, the dendrimeric catalyst showed activity for the Heck cross-coupling in a biphasic fluorous/organic system. The study also addresses challenges associated with catalyst recovery in both organic and non-conventional solvents. Comparisons between precisely and stochastically difunctionalized dendrimers underscore positive multivalence and generation dendritic effects in specific reactions. Notably, higher activity of precisely substituted dendrimers from generation 1 to 3 compared to stochastically substituted homologues was demonstrated in the Stille cross-coupling. In summary, this research provides a thorough examination of dendrimer synthesis, functionalization, and catalytic applications, offering valuable insights and suggesting avenues for future refinement in sustainable catalytic processes
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Billodeaux, Damon Ray. « Investigations on the use of main group metal complexes of salen ligands as catalysts for the copolymerization of CO2 and epoxides ». Texas A&M University, 2005. http://hdl.handle.net/1969.1/2425.
Texte intégralRésumé :
Current industrial processes for the production of polycarbonates, a thermoplastic valued for commercial applications, leave much to be desired from an environmental viewpoint. Research into alternative methods for production of polycarbonates has focused on the copolymerization of carbon dioxide and epoxides for the benefits of eliminating phosgene as a reagent, and for the economic impact of incorporating CO2 as a low cost C1 feedstock. Early work in this field focused on the use of zinc-derived catalysts, but recent studies indicate that chromium complexes of the salen (N,N-bis-(salicylidene)-1,2-ethylene diimine) family of ligands are far superior to the zinc complexes in terms of reactivity and diminishing the formation of unwanted byproducts.
Concomitant to the studies of chromium salen complexes, investigations of main-group salen metal complexes were carried out. Aluminum complexes were able to produce polycarbonate in the presence of tetrabutyl ammonium salts and neutral Lewis bases. Gallium complexes were essentially inactive for generating any product. Tin(IV) complexes were active for the production of polyether, the result of homopolymerization of epoxide without CO2 insertion. Tin(II) complexes generated the monomeric cyclic carbonate product but no copolymer.
An additional aspect of research relative to this field of study is the development of polymeric materials from several different epoxide monomers. The complex [hydrotris(3-phenyl-pyrazol-1-yl)borate]Cd(II) acetate was used to study the thermodynamics of the binding of a series of potential epoxide monomers to a metal center via 113Cd NMR. Activation of the epoxide by a metal center was found to not play a significant role in the ability of the complex to be subsequently ring-opened for polymerization.
A final relevant area of study involved the synthesis of cadmium analogues of Fe/Zn double metal cyanide (DMC) complexes. Heterogeneous DMCs are well known in patent literature as excellent catalysts for the production of polycarbonates and cyclic carbonates from CO2 and epoxides. Previous studies on homogeneous Fe/Zn DMCs have only provided cyclic carbonate. Cd analogues of these species provide a convenient NMR handle for studies on the activity of the metal centers in presence of an epoxide and by changes to the DMC structure.
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Fogeron, Thibault. « Synthèse de complexes inspirés des formiate déshydrogénases à Mo/W : application à la catalyse moléculaire de la réduction du CO2 ». Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS132.
Texte intégralRésumé :
Dans le contexte du réchauffement climatique, la recherche de sources d’énergie propres et durables est l’un des défis les plus importants de notre époque. La réduction du CO2 permettrait un stockage des énergies renouvelables et une diminution de la concentration de ce gaz dans l’atmosphère. Le développement de catalyseurs moléculaires permet d’étudier avec précision les relations entre structures et réactivités. Malheureusement, la librairie de catalyseurs homogènes existant dans la littérature est réduite. Afin de chercher de nouveaux catalyseurs potentiels, nous avons décidé de nous inspirer du site actif des formiate déshydrogénases (FDH). La synthèse de molécules mimes de ce site actif constitue un challenge intéressant. Dans cette thèse, nous décrivons l’obtention de deux ligands, inspirés de la molybdoptérine (chapitre I). L’obtention des complexes CoCp(dithiolène) a permis de mieux caractériser ces ligands (chapitre II). De plus, l’observation de la réactivité des ligands dans les conditions électrochimiques nous a permis d’anticiper leurs comportements lors des études catalytiques. L’obtention des complexes [MoO(dithiolène)2]2- à partir des ligands bio-inspirés constitue les synthèses de mimes des sites actifs des FDH les plus abouties de la littérature (chapitre III). Ce chapitre a également été l’occasion de travailler sur la généralisation de méthodologies de synthèses. Les complexes [Ni(dithiolène)2]- obtenus à partir des ligands bio-mimétiques constituent les premiers catalyseurs dithiolène pour la réduction du CO2 (chapitre IV). Ils font partie des rares complexes homogènes à base de métaux non-nobles catalysant la réduction du CO2 en formiateIn the context of global warming, the development of new sources of energy, clean and sustainable, is a key challenge of our society. The reduction of CO2 could allow the storage of renewable energies and offer an answer to the dramatic increase of CO2 in the atmosphere. Development of molecular catalysts offers the possibility of studying the structure-reactivity relationships. However, the library of existing homogeneous catalysts in the literature is quite limited. In order to find new potential catalysts, we decided to take inspiration from the active site of formate dehydrogenases (FDH). The synthesis of molecules mimicking this active site is an interesting challenge. In this thesis, we described the synthesis of two ligands inspired from the molybdopterin (chapter I). The synthesis of CoCp(dithiolène) complexes allows us to better characterize these ligands (chapter II). Moreover, the observation of the reactivity of these ligands allows us to understand their behaviour during electrocatalysis. The [MoO(dithiolene)2]2- complexes obtained from the bio-inspired ligands are,so far, the best mimics of the active site of FDH in the literature (chapter III). In this chapter, the generalization of synthetic procedure was also explored. Finally, [Ni(dithiolene)2]- synthesize from the bio-inspired ligands are the first dithiolene complexes able to reduce CO2 (chapter IV). They are among the few non-nobles metal complexes catalyzing the reduction of CO2 into formate
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Cardoso, Amanda da Silva. « Estudo da corrosão de ligas Fe-Cr-Mo em água artificial de tanque de armazenamento de petróleo saturada com CO2 ». reponame:Repositório Institucional da UFC, 2012. http://www.repositorio.ufc.br/handle/riufc/9602.
Texte intégralRésumé :
CARDOSO, A. S.; Estudo da corrosão de ligas Fe-Cr-Mo em água artificial de tanque de armazenamento de petróleo saturada com CO2. 2012. 50 f. Dissertação (Mestrado em Química) - Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2012.Submitted by José Jairo Viana de Sousa (jairo@ufc.br) on 2014-10-15T19:28:50Z No. of bitstreams: 1 2012_dis_ascardoso.pdf: 1550155 bytes, checksum: 52c246f369a8b1fdd15b0b9052264efa (MD5)
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The objective of this work was to evaluate the influence of the percentage in mass of Mo in Fe-Cr-Mo alloys against CO2 corrosion in artificial water of oil storage tank and to propose an experimental alloy to be used in susceptible to this kind of corrosion pipes. They had been studied the 1020 carbon steel, for comparison, and two types of Fe-Cr-Mo alloys, one advertising, called P9 (Fe-9Cr-1Mo); and one experimental alloy, E (Fe-9Cr-5Mo). They had been made measurements of LSP with time of Eoc of 1 h. The curves had shown that, in 1020 steel, the dissolution of Fe occurs only, whereas, with the increase of the percentage of Mo, occurs passivation. Monitoring of the corrosion was made by electrochemical impedance spectroscopy, throughout 168 h of immersion. Nyquist diagrams had shown that the increase of Mo content increased the impedance of the studied alloys. Although, the Bode representations showed that there is only one process in the corrosion of 1020 steel, while there are two ones for P9 and E alloys. The characterization of the surface was made by SEM. The distribution of the corrosion products was homogeneous in the 1020 steel and heterogeneous one in the other alloys. The identification of the corrosion products was made by RAMAN spectroscopy, showing that there was protective corrosion products formation only to Fe-Cr-Mo alloys and that only the E alloy presented Mo-containing products. This is in agreement with the results obtained in polarization curves and in impedance diagrams, once Mo can stabilizes passivation films. So, experimental E alloy can be used in substitution of P9 alloy in oil exploration plants susceptible to CO2 corrosion.
O objetivo deste trabalho foi avaliar a influência da porcentagem em massa de Mo em ligas Fe-Cr-Mo frente à corrosão por CO2 em água artificial de tanque de armazenamento de petróleo e propor uma liga experimental para ser usada em dutos suscetíveis a esse tipo de corrosão. Foram estudados o aço carbono 1020, para comparação, e dois tipos de ligas Fe-Cr-Mo, uma comercial, denominada P9 (Fe-9Cr-1Mo); e uma liga experimental, E (Fe-9Cr-5Mo). Foram feitas medidas de PLP com tempo de Eca de 1 h. As curvas mostraram que, no aço 1020, ocorre apenas a dissolução do Fe, enquanto que, com o aumento da porcentagem de Mo, ocorre passivação. O monitoramento da corrosão foi feito por espectroscopia de impedância eletroquímica, ao longo de 168 h de imersão. Os diagramas de Nyquist mostraram que o aumento na quantidade de Mo aumenta a impedância das ligas estudadas. Já as representações de Bode mostraram que há apenas um processo na corrosão no aço 1020, enquanto que há dois para as ligas P9 e E. A caracterização da superfície foi feita por MEV. A distribuição dos produtos de corrosão foi homogênea no aço 1020 e heterogênea nas demais ligas. A identificação dos produtos de corrosão foi feita por espectroscopia RAMAN, mostrando que houve a formação de produtos de corrosão protetores apenas para as ligas Fe-Cr-Mo e que apenas a liga E apresentou produtos contendo Mo. Isso está em acordo com os resultados obtidos nas curvas de polarização e nos diagramas de impedância, uma vez que o Mo pode estabilizar filmes de passivação. Assim, a liga experimental E pode ser usada em substituição à liga comercial P9 em plantas de exploração de petróleo suscetíveis a corrosão por CO2.
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Nambukara, Wellala Nadeesha P. « Synthesis and Catalytic Activities of Nickel Complexes Bearing Flexible Tridentate Ligands ». University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491561548324255.
Texte intégral
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Christophe, Thierry. « Etude de la régulation du récepteur de l'anaphylatoxine C5a : identification de ligands des récepteurs de la famille FPR ». Université Joseph Fourier (Grenoble), 2000. http://www.theses.fr/2000GRE10229.
Texte intégralRésumé :
Les leucocytes peuvent etre actives par des agents chimioattractants tels que des peptides bacteriens (fmlp) ou la fraction c5a du complement. Ces agents chimioattractants induisent la migration des leucocytes, leur degranulation et l'activation du complexe nadph oxydase qui produit les ions superoxyde impliques dans la destruction des pathogenes. Ces reponses cellulaires sont declenchees par la fixation de ces agents sur des recepteurs specifiques qui appartiennent a la superfamille des recepteurs couples aux proteines g heterotrimeriques. Malgre la presence continue d'agonistes, les reponses cellulaires sont transitoires et les cellules deviennent refractaires a une autre stimulation (desensibilisation homologue). Selon le concept actuel, le recepteur est phosphoryle, ce qui permet son interaction avec la proteine adaptatrice -arrestine. Cette interaction inhibe le couplage recepteur/proteine g et induit l'internalisation du recepteur par les puits recouverts de clathrine. Apres addition de c5a, le recepteur du c5a (rc5a) est phosphoryle sur six serines de la queue c-terminale intracellulaire. En utilisant des recepteurs dont certaines serines ont ete mutees, nous avons montre que : (1) cette phosphorylation suit un processus hierarchique, debutant par la phosphorylation des serines s334 et s332. (2) la phosphorylation de la serine s338 est necessaire au decouplage recepteur/proteine g. (3) le decouplage et l'internalisation de rc5a sont deux processus independants. (4) dans les cellules promyelocytaires hl-60, rc5a peut etre internalise par un mecanisme independant de la phosphorylation. Rc5a peut egalement etre internalise par la voie classique dependante de la phosphorylation. Ces deux mecanismes sont sensibles au dominant negatif de la dynamine, une gtpase qui intervient au niveau de la membrane dans la fermeture des vesicules d'endocytose, suggerant l'implication des puits recouverts de clathrine. D'autre part, nous avons identifie le peptide synthetique wkymvm comme un agoniste des recepteurs fpr, fprl1 et fprl2 ; wkymvm est specifique de fprl1 et fprl2. Un peptide antibacterien produit par helicobacter pylori (hp(2-20)) est egalement un agoniste de fprl1 et fprl2.
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Baffert, Mathieu. « Synthesis of ruthenium complexes having one or more N-heterocyclic carbene ligands supported on hybrid mesostructured silicas and their use in the hydrogenation of carbon dioxide ». Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00838661.
Texte intégralRésumé :
The goal of this PhD was to elaborate supported Ru-NHC catalytic materials based on hybrid organic-inorganic materials having imidazolium units perfectly distributed within a silica matrix. Passivation of these imidazolium materials followed by formation of NHC-carbene and reaction with [RuCl2(p-cymene)]2 provided these well-defined surface sites of general structures RuCl2(NHC)(L), where L was para-cymene (p-cymene) or THF depending on the reaction conditions, which could be further replaced by PMe3. These systems were then tested in the hydrogenation of CO2 in presence of amine to give formamides. The mono-NHC systems were highly active only in the presence of PMe3 ligands, but suffered from Ru leaching, evidencing the low stability of the NHC-Ru bond under the reaction conditions. On the other hand, dinuclear bis-NHC Ru systems were also developed, and they displayed much improved activity and stability in the hydrogenation of CO2 in the presence of PMe3 compared to the mono-NHC systems. This allowed the use of much higher reaction temperatures (200 °C) and provided heterogeneous catalysts with performances close to those obtained with the best homogeneous catalysts, Cl2Ru(dppe)2.
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Damineli, Bruno Luís. « Conceitos para formulação de concretos com baixo consumo de ligantes : controle reológico, empacotamento e dispersão de partículas ». Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-19092014-103459/.
Texte intégralRésumé :
Devido à demanda dos países em desenvolvimento, a produção de cimento e as emissões de CO2 relacionadas aumenta progressivamente, colocando esta indústria sob pressão devido às preocupações com o aquecimento global. Como diminuir a produção não é uma opção sustentável do ponto de vista social, deve-se primar pela diminuição dos impactos ambientais mantendo-se o aumento da produção. Porém, as principais estratégias de redução das emissões substituição de clínquer por adições, aumento da eficiência de fornos e uso de combustíveis alternativos não são capazes de uma redução que compense o crescimento da produção, mesmo com a disseminação dos maiores esforços industriais possíveis, devido a limites tecnológicos e de disponibilidade de materiais. A captura e sequestro de carbono, por sua vez, pode vir a aumentar significativamente o custo do cimento, prejudicando justamente os países mais necessitados. Novas alternativas são necessárias. Uma delas, ainda pouco desenvolvida, é o aumento da eficiência do uso dos ligantes em materiais cimentícios, como os concretos. Esta tese tem o objetivo de explorar o potencial desta estratégia para contribuir à mitigação das emissões de CO2 da cadeia concreto/cimento. O êxito nesta tarefa tem relação direta com o uso de ferramentas de empacotamento e dispersão de partículas para permitir comportamento reológico adequado à aplicação com uso de menor teor de água na mistura. O trabalho foi dividido em três etapas: 1) levantamento de dados para criação de benchmark da tecnologia atual de concretos com relação e eficiência no uso dos ligantes através de dois indicadores de eficiência Índice de Ligantes (IL) e Índice de CO2 (IC); 2) levantamento da teoria de empacotamento e dispersão de partículas; e 3) estudo experimental demonstrando como a eficiência do uso dos ligantes pode ser aumentada através da aplicação dos conceitos da etapa 2, do controle mais preciso do comportamento reológico e do uso de finos inertes para substituir clínquer para obtenção de parâmetros reológicos. Concluiu-se que o potencial de aumento da eficiência é superior a 50%. Porém, sua implantação em escala comercial dependeria de aumento do controle tecnológico das dosagens de concreto e de profundas modificações na cadeia produtiva e na definição de agregados, fillers, cimento e ligantes.Due to the increasing demand of developing countries, cement production and related CO2 emissions increases steadily, putting industry under pressure due to global warming constraints. As decreasing production is not a sustainable option from social point of view, environmental loads need to be decreased even maintaining the increase of production. However, current strategies for reducing emissions clinker replacement by mineral additions, increase of kiln efficiency and the use of alternative fuels are not capable of a reduction which could compensate the increasing in production, even with the dissemination of highest industrial efforts due to technological and materials availability limits. Carbon capture and storage, by the time, could increase significantly cement cost, which could harm exactly the neediest countries. New alternatives are needed. One of them, few developed yet, is increasing the efficiency of binder use on cementitious materials, such as concretes. This thesis has the aim of exploring the potential of this strategy for contributing to the mitigation of CO2 emissions of concrete/cement chain. The success in this task is directly related to the use of tools of packing and dispersion of particles for allowing an adequate rheological behavior for the application but with a lower water content in the mixture. The thesis was divided in three main steps: 1) literature research for creating a benchmark of current concrete technology in terms of binder efficiency by two efficiency indexes Binder Intensity (BI) and CO2 Intensity (CI); 2) research of particles packing and dispersion theory; and 3) experimental planning for demonstrating how the binder use efficiency can be significantly increased by the use of concepts from step 2, a more precise rheological behavior control and the use of inert fillers for replacing clinker to obtain rheological parameters. It could be concluded that the potential of efficiency increase is higher than 50%. However, the implantation in commercial scale would depend on the increase of technological control in concrete designs, and also on deep changes in the productive chain and in the definitions of aggregates, fillers, cement and binders.
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Gautier, Quentin, et Quentin Gautier. « Cinétiques de précipitation de minéraux carbonatés magnésiens, influence de ligands organiques et conséquences pour la séquestration minérale du CO2 ». Phd thesis, Université Paris-Est, 2012. http://pastel.archives-ouvertes.fr/pastel-00806512.
Texte intégralRésumé :
La formation de minéraux carbonatés magnésiens par carbonatation de silicates de magnésium constitue une option pérenne et sûre de séquestration du dioxyde de carbone, dont les estimations les plus optimistes indiquent qu'elle pourrait participer significativement à l'effort global de réduction des émissions de CO2 d'origine anthropique. À ce jour cependant, ces réactions chimiques se heurtent à de fortes limitations cinétiques, dont l'origine réside dans la faible réactivité des phases minérales en présence. Alors que de nombreuses études se sont intéressées à la phase de dissolution des silicates magnésiens, souvent considérée comme l'étape limitante du processus, ce travail de thèse prend le parti d'étudier expérimentalement les mécanismes et les vitesses de formation des minéraux carbonatés magnésiens qui constituent le produit final des réactions de carbonatation. Dans une première partie, nous nous intéressons à l'influence sur la cinétique de précipitation de la magnésite (MgCO3) de ligands organiques connus pour accélérer la vitesse de dissolution des silicates magnésiens : oxalate, citrate et EDTA. Sur la base d'expériences menées en réacteur à circulation entre 100 et 150°C, nous montrons que ces ligands diminuent significativement la vitesse de précipitation de la magnésite en raison (1) de la complexation des cations Mg2+ en solution, estimée grâce à une base de données thermodynamiques établie à partir d'une revue critique de la littérature, et (2) de l'adsorption des ligands au niveau d'un nombre limité de sites à la surface du minéral, avec pour conséquence une diminution de la constante cinétique de précipitation. Cette inhibition de la cristallisation de la magnésite est maximale dans le cas du citrate. L'utilisation de la microscopie à force atomique en conditions hydrothermales nous a permis de sonder l'origine de l'inhibition observée. Elle nous indique en particulier que le citrate et l'oxalate agissent sur le processus de croissance cristalline à la surface de la magnésite, modifiant la forme des îlots de croissance ainsi que la fréquence de génération des marches cristallines par le processus de croissance en spirale. Nous montrons que ces deux ligands agissent au niveau de sites surfaciques différents, probablement fonction de leurs structures et de leurs propriétés chimiques. Nous proposons que l'inhibition plus forte exercée par le citrate sur le processus de croissance de la magnésite provienne d'une interaction préférentielle du ligand avec les marches cristallines aigües, qui limitent le processus de croissance en spirale de par leur faible vitesse d'avancement. La description de ces phénomènes à l'aide d'une loi cinétique empirique permet d'effectuer une modélisation numérique simple de la carbonatation de la forstérite (Mg2SiO4) en présence de ligands à 120°C, qui suggère que les ligands organiques étudiés ont une influence défavorable sur le processus global de carbonatation de ce minéral .La troisième et dernière partie de ce travail s'intéresse à la solubilité et à la cinétique de précipitation d'un carbonate de magnésium hydraté, l'hydromagnésite, entre 25 et 75°C. Les résultats obtenus indiquent que la vitesse de croissance de l'hydromagnésite excède largement celle de la magnésite à affinité chimique comparable, tandis que l'énergie d'activation du processus est beaucoup plus faible que celle de la magnésite. Ces données cinétiques originales confirment que la déshydratation des ions Mg2+ est l'étape limitante de la précipitation de la magnésite en solution aqueuse. Toutefois, du fait de sa solubilité plus forte, l'hydromagnésite n'est susceptible de se former plus rapidement que la magnésite qu'à pH alcalin et basse température. Elle ne peut à ce titre constituer un palliatif à la faible vitesse de précipitation de la magnésite lors de la carbonatation des silicates magnésiens
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Gautier, Quentin. « Cinétiques de précipitation de minéraux carbonatés magnésiens, influence de ligands organiques et conséquences pour la séquestration minérale du CO2 ». Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1128/document.
Texte intégralRésumé :
La formation de minéraux carbonatés magnésiens par carbonatation de silicates de magnésium constitue une option pérenne et sûre de séquestration du dioxyde de carbone, dont les estimations les plus optimistes indiquent qu'elle pourrait participer significativement à l'effort global de réduction des émissions de CO2 d'origine anthropique. À ce jour cependant, ces réactions chimiques se heurtent à de fortes limitations cinétiques, dont l'origine réside dans la faible réactivité des phases minérales en présence. Alors que de nombreuses études se sont intéressées à la phase de dissolution des silicates magnésiens, souvent considérée comme l'étape limitante du processus, ce travail de thèse prend le parti d'étudier expérimentalement les mécanismes et les vitesses de formation des minéraux carbonatés magnésiens qui constituent le produit final des réactions de carbonatation. Dans une première partie, nous nous intéressons à l'influence sur la cinétique de précipitation de la magnésite (MgCO3) de ligands organiques connus pour accélérer la vitesse de dissolution des silicates magnésiens : oxalate, citrate et EDTA. Sur la base d'expériences menées en réacteur à circulation entre 100 et 150°C, nous montrons que ces ligands diminuent significativement la vitesse de précipitation de la magnésite en raison (1) de la complexation des cations Mg2+ en solution, estimée grâce à une base de données thermodynamiques établie à partir d'une revue critique de la littérature, et (2) de l'adsorption des ligands au niveau d'un nombre limité de sites à la surface du minéral, avec pour conséquence une diminution de la constante cinétique de précipitation. Cette inhibition de la cristallisation de la magnésite est maximale dans le cas du citrate. L'utilisation de la microscopie à force atomique en conditions hydrothermales nous a permis de sonder l'origine de l'inhibition observée. Elle nous indique en particulier que le citrate et l'oxalate agissent sur le processus de croissance cristalline à la surface de la magnésite, modifiant la forme des îlots de croissance ainsi que la fréquence de génération des marches cristallines par le processus de croissance en spirale. Nous montrons que ces deux ligands agissent au niveau de sites surfaciques différents, probablement fonction de leurs structures et de leurs propriétés chimiques. Nous proposons que l'inhibition plus forte exercée par le citrate sur le processus de croissance de la magnésite provienne d'une interaction préférentielle du ligand avec les marches cristallines aigües, qui limitent le processus de croissance en spirale de par leur faible vitesse d'avancement. La description de ces phénomènes à l'aide d'une loi cinétique empirique permet d'effectuer une modélisation numérique simple de la carbonatation de la forstérite (Mg2SiO4) en présence de ligands à 120°C, qui suggère que les ligands organiques étudiés ont une influence défavorable sur le processus global de carbonatation de ce minéral .La troisième et dernière partie de ce travail s'intéresse à la solubilité et à la cinétique de précipitation d'un carbonate de magnésium hydraté, l'hydromagnésite, entre 25 et 75°C. Les résultats obtenus indiquent que la vitesse de croissance de l'hydromagnésite excède largement celle de la magnésite à affinité chimique comparable, tandis que l'énergie d'activation du processus est beaucoup plus faible que celle de la magnésite. Ces données cinétiques originales confirment que la déshydratation des ions Mg2+ est l'étape limitante de la précipitation de la magnésite en solution aqueuse. Toutefois, du fait de sa solubilité plus forte, l'hydromagnésite n'est susceptible de se former plus rapidement que la magnésite qu'à pH alcalin et basse température. Elle ne peut à ce titre constituer un palliatif à la faible vitesse de précipitation de la magnésite lors de la carbonatation des silicates magnésiensForming magnesium carbonate minerals through carbonation of magnesium silicates has been proposed as a safe and durable way to store carbon dioxide, with a possibly high potential to offset anthropogenic CO2 emissions. To date however, chemical reactions involved in this process are facing strong kinetic limitations, which originate in the low reactivity of both Mg-silicates and Mg-carbonates. Numerous studies have focused on the dissolution of Mg-silicates, under the questionable hypothesis that this step limits the whole process. This thesis work focuses instead on the mechanisms and rates of formation of magnesium carbonates, which are the final products of carbonation reactions. The first part of the work is dedicated to studying the influence on magnesite precipitation kinetics of three organic ligands known to accelerate Mg-silicates dissolution rates : oxalate, citrate and EDTA. With help of mixed-flow reactor experiments performed between 100 and 150°C, we show that these ligands significantly reduce magnesite growth rates, through two combined mechanisms: (1) complexation of Mg2+ cations in aqueous solution, which was rigorously estimated from a thermodynamic database established through a critical review of the literature, and (2) adsorption of ligands to a limited number of surface sites, leading to a decrease of the precipitation rate constant. The observed growth inhibition is maximal with citrate. We then used hydrothermal atomic force microscopy to probe the origin of the documented growth inhibition. Our observations show that citrate and oxalate interact with the crystal growth process on magnesite surface, modifying the shape of growth hillocks as well as the step generation frequency through spiral growth. We also show that the ligands adsorb preferentially on different kink-sites, which is probably related to their different structures and chemical properties. We propose that the stronger magnesite growth inhibition caused by citrate is related to a preferential interaction of the ligand with acute steps on the magnesite surface, which limit the spiral growth process through their low advancement rate. The description of these processes with an empirical rate law allows performing simple numerical simulations of forsterite carbonatation at 120°C in the presence of the ligands. We thus demonstrate that the use of the investigated ligands would clearly be detrimental to the carbonation of forsterite. The third and last part of this work deals with hydromagnesite solubility and growth kinetics between 25 and 75°C. The obtained results show that hydromagnesite growth rates largely exceed magnesite rates at comparable chemical affinity, while the activation energy of the process is much smaller than for magnesite. This original kinetic dataset thus confirms the long-standing hypothesis that Mg2+ dehydration is the rate-limiting step for Mg-carbonate precipitation from aqueous solution. However, due to its higher solubility, hydromagnesite may grow more quickly than magnesite only at low temperature and alkaline pH. Thus, it may not provide a solution to the sluggish precipitation kinetics of magnesite during Mg-silicates carbonation
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Cardoso, Amanda da Silva. « Estudo da corrosÃo de ligas Fe-Cr-Mo em Ãgua artificial de tanque de armazenamento de petrÃleo saturada com CO2 ». Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8477.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorConselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
O objetivo deste trabalho foi avaliar a influÃncia da porcentagem em massa de Mo em ligas Fe-Cr-Mo frente à corrosÃo por CO2 em Ãgua artificial de tanque de armazenamento de petrÃleo e propor uma liga experimental para ser usada em dutos suscetÃveis a esse tipo de corrosÃo. Foram estudados o aÃo carbono 1020, para comparaÃÃo, e dois tipos de ligas Fe-Cr-Mo, uma comercial, denominada P9 (Fe-9Cr-1Mo); e uma liga experimental, E (Fe-9Cr-5Mo). Foram feitas medidas de PLP com tempo de Eca de 1 h. As curvas mostraram que, no aÃo 1020, ocorre apenas a dissoluÃÃo do Fe, enquanto que, com o aumento da porcentagem de Mo, ocorre passivaÃÃo. O monitoramento da corrosÃo foi feito por espectroscopia de impedÃncia eletroquÃmica, ao longo de 168 h de imersÃo. Os diagramas de Nyquist mostraram que o aumento na quantidade de Mo aumenta a impedÃncia das ligas estudadas. Jà as representaÃÃes de Bode mostraram que hà apenas um processo na corrosÃo no aÃo 1020, enquanto que hà dois para as ligas P9 e E. A caracterizaÃÃo da superfÃcie foi feita por MEV. A distribuiÃÃo dos produtos de corrosÃo foi homogÃnea no aÃo 1020 e heterogÃnea nas demais ligas. A identificaÃÃo dos produtos de corrosÃo foi feita por espectroscopia RAMAN, mostrando que houve a formaÃÃo de produtos de corrosÃo protetores apenas para as ligas Fe-Cr-Mo e que apenas a liga E apresentou produtos contendo Mo. Isso està em acordo com os resultados obtidos nas curvas de polarizaÃÃo e nos diagramas de impedÃncia, uma vez que o Mo pode estabilizar filmes de passivaÃÃo. Assim, a liga experimental E pode ser usada em substituiÃÃo à liga comercial P9 em plantas de exploraÃÃo de petrÃleo suscetÃveis a corrosÃo por CO2.
The objective of this work was to evaluate the influence of the percentage in mass of Mo in Fe-Cr-Mo alloys against CO2 corrosion in artificial water of oil storage tank and to propose an experimental alloy to be used in susceptible to this kind of corrosion pipes. They had been studied the 1020 carbon steel, for comparison, and two types of Fe-Cr-Mo alloys, one advertising, called P9 (Fe-9Cr-1Mo); and one experimental alloy, E (Fe-9Cr-5Mo). They had been made measurements of LSP with time of Eoc of 1 h. The curves had shown that, in 1020 steel, the dissolution of Fe occurs only, whereas, with the increase of the percentage of Mo, occurs passivation. Monitoring of the corrosion was made by electrochemical impedance spectroscopy, throughout 168 h of immersion. Nyquist diagrams had shown that the increase of Mo content increased the impedance of the studied alloys. Although, the Bode representations showed that there is only one process in the corrosion of 1020 steel, while there are two ones for P9 and E alloys. The characterization of the surface was made by SEM. The distribution of the corrosion products was homogeneous in the 1020 steel and heterogeneous one in the other alloys. The identification of the corrosion products was made by RAMAN spectroscopy, showing that there was protective corrosion products formation only to Fe-Cr-Mo alloys and that only the E alloy presented Mo-containing products. This is in agreement with the results obtained in polarization curves and in impedance diagrams, once Mo can stabilizes passivation films. So, experimental E alloy can be used in substitution of P9 alloy in oil exploration plants susceptible to CO2 corrosion.
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Juvenal, Frank. « Polymères de coordination luminescents 1D et 2D avec des ligands rigides contenant du Pt(II) montrants des propriétés d’adsorption du CO2 ». Mémoire, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/10578.
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La conception de nouveaux matériaux fonctionnels a une longue histoire. Durant les deux dernières décennies, le domaine des polymères organiques et inorganiques a attiré l'attention des chercheurs. Plus important encore, les matériaux poreux tels que les Metal Organic Frameworks (MOFs), en anglais, Covalent Organic Frameworks (COFs), en anglais, ainsi que des polymères de coordination poreux sont maintenant étudiés de manière intensive en raison de leurs applications potentielles, comprenant le stockage de gaz, la séparation de gaz, la catalyse et la détection. D'un autre côté, les polymères contenant du Pt ont montré l'application potentielle dans les cellules solaires et les diodes électroluminescentes. Le mémoire est divisé en trois sections principales présentant des résultats nouveaux. Dans la première section, le chapitre 2 traite essentiellement de la formation de polymères de coordination (CP) avec des sels CuX (X = Cl, Br, I) et trans-[p-MeSC6H4C≡C-Pt(PMe3)2-C≡CC6H4SMe] (L1), soit dans le PrCN ou PhCN. Les polymères résultants sont soit 2D (bidimensionel) ou 1D (unidimensionel). Cependant, en presence de PrCN ou de PhCN, le CP 2D obtenu avec le CuBr n'a pas incorporé de solvant dans ses espaces vides. D'autre part, le CP 2D et le reste des CP 1D obtenus avaient soit des molécules de solvant de cristallisation dans leurs cavités ou coordonnés au cuivre sur la chaîne. Les unités cuivre-halogénures étaient soit des rhomboïdes Cu2X2 ou le cubane Cu4I4. Leurs mesures photophysiques en présence et en l'absence de molécules de solvant de cristallisation ont été effectuées. En outre, la porosité du CP a été évaluée par BET (N2 à 77 K). Le vapochromisme du CP 2D sans solvant et des CP 1D ont été étudiés, ainsi que les mesures de sorption du CO2 ont été effectuées. De plus, nous avons utilisé CuCN et L1 dans MeCN pour former de nouveaux CP’s. Ceci est rapporté dans la deuxième section, le chapitre 3. Le CP obtenu était inattendu : L1 s’est rompu et du cyanure CN‾ s’est coordonné sur le Pt. Ceci a conduit à la formation d’un CP 1D zigzag. Généralement, les CP sont formés avec L1 via des liens Cu-S ou/et Cu([éta]2-C≡C), mais pas dans le cas du CuCN qui lui forme une chaîne 1D (CuCN)n où le L1 rompu se lie avec cette chaîne via un lien Cu-N. Les propriétés photophysiques et de stabilité thermique ont été étudiées. La troisième section (Chapitre 4) traite d'une exploration des CP formés par la reaction des sels CuX (X = Cl, Br, I) et le trans-[p-MeSC6H4C≡C-Pt(PMe3)2-C≡CC6H4SMe] (L1) ou le trans-[p-MeSC6H4C≡C-Pt(PEt3)2-C≡CC6H4SMe] (L2) dans du MeCN afin de trouver des tendances. L'utilisation de L1 a donné lieu à un CP 2D ou 1D CPs avec le MeCN piégé à l'intérieur des cavités, il y a de l’espace vide. L2 a conduit uniquement à des CP 1D sans molecules de solvant de cristallisation. Des analyses thermogravimétriques, photophysique et des mesures d’adsorption de gaz (uniquement pour ceux avec du solvant) ont été étudiées.Abstract: The design of new functional materials has a long history. For the past two decades, the field of organic and inorganic polymers has attracted attention of researchers. More importantly, porous materials such as Metal Organic Frameworks (MOFs), Covalent Organic Frameworks (COFs) as well as porous coordination polymers are now being intensively studied due to their potential applications including gas storage, gas separations, catalyst and sensing. On another hand, Pt-containing polymers have shown potential applications in solar cells and light emitting diodes. The masters’ thesis is mainly divided into three main sections presenting new results. In the first section; Chapter 2 mainly discusses the formation of coordination polymers with CuX salts (X= Cl, Br, I) and trans-[p-MeSC6H4C≡C-Pt(PMe3)2-C≡CC6H4SMe] (L1), in either PrCN or PhCN. The resulting polymers obtained were 2D (bidimensional) CPs or 1D (unidimensional) CPs in all cases. However, 2D CPs obtained when CuBr salt is used by either using PrCN or PhCN did not incorporate the solvents in their cavities. On the other hand, the 2D CP and the rest of 1D CPs obtained had either the crystallization molecules in the cavities or coordinated to the copper cluster. The copper-halide clusters were either the rhomboids Cu2X2 fragments or the step cubane Cu4I4. The photophysical measurements in the presence and absence of solvent crystallization molecules were performed. In addition, the porosity of the CPs was evaluated by adsorption isotherms. The vapochromism of the solvent-free 2D and 1D CPs were investigated as well as CO2 sorption measurements were perfomed. Furthermore, we then attempted to use CuCN and L1 in MeCN which is reported in the second section as Chapter 3. The obtained CP was unexpected as L1 broke and a cyanide (CN‾) ion coordinated to the Pt atom leading to the formation of zigzag 1D CP. The coordination bonds Cu-S or/and Cu([eta]2-C≡C) were generally observed with L1, but not in the CuCN case. Instead a 1D chain of (CuCN)n was made and the broken L1 now binds the chain via a Cu-N bond. The photophysical and thermal stability properties were studied. Lastly, the third section, Chapter 4 deals with a potential predictability of CP formation by using CuX salts (X= Cl, Br, I) and either trans-[p-MeSC6H4C≡C-Pt(PMe3)2-C≡CC6H4SMe] (L1) or trans-[p-MeSC6H4C≡C-Pt(PEt3)2-C≡CC6H4SMe] (L2) in MeCN as the solvent. The use of L1 resulted in either 2D or 1D CPs with the MeCN trapped inside of the cavities while L2 resulted in 1D CPs without MeCN being present in their cavities. The thermogravimetric, photophysical as well as gas sorption measurements (only for those with crystalisation molecules) were perfomed.
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Eckstein, Ilton Isandro. « Tipificação dos fatores ligados ao manejo de ordenha e avaliação do seu impacto sobre a qualidade sanitária do leite ». Universidade Estadual do Oeste do Paraná, 2012. http://tede.unioeste.br:8080/tede/handle/tede/1645.
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Previous issue date: 2012-03-30Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Knowing the factors that affect the composition and quality of milk in Dairy Production Systems (SPL) is of utmost importance to the producer. The objective was to evaluate the characteristics of 32 SPL in the city of Toledo, together in partnership with a dairy. We performed the data collection of properties, with the aid of a semi-structured questionnaire, which collected information on the production traits, milk composition and quality, besides the technical and management practices carried out, mainly related to hygiene and management health of milking. Milk samples were analyzed for their composition (fat, protein, lactose and total solids), Somatic Cell Count (SCC), Total Bacterial Count (TBC), and also to the presence of total coliforms and fecal coliforms. Subsequently, data collection, the variables were selected and analyzed using multivariate techniques, using the principal component analysis (PCA) and analysis of Ascendant Hierarchical Classification (AHC). We analyzed variables related to production and milk quality, techniques and practices used at the time of milking, feeding management, milking system and socio-cultural variables related to the producer. The variables that best explained the differences in the PCA were related to the hygienic and sanitary practices (pre and post-dipping, use of detergents in alkaline and acid cleaning, testing for mastitis) held for milking, with the composition of milk and linked to the producer (age, education, length of service). It was found that the use of these practices can help to improve production and milk quality, ensuring a raw material with high commercial value. The grouping of production systems has shown that there is great diversity among the forms of production, allowing identifying the factors that can influence it, in order to form strategies that may result from gains in production and milk quality
Conhecer os fatores que afetam a composição e qualidade do leite em Sistemas de Produção Leiteiros (SPL) é de extrema importância ao produtor. Objetivou-se avaliar as características de 32 SPL, na cidade de Toledo, juntamente em parceria com um laticínio. Foi realizada a coleta de dados das propriedades, com o auxílio de um questionário semi-estruturado, onde se colheu informações acerca das características de produção, composição e qualidade do leite, além das técnicas e práticas de manejo realizadas, principalmente relacionadas ao manejo higiênico-sanitário de ordenha. As amostras de leite foram analisadas em relação a sua composição (gordura, proteína, lactose e sólidos totais), Contagem de Células Somáticas (CCS), Contagem Bacteriana Total (CBT), e também para presença de coliformes totais e coliformes termotolerantes. Posteriormente, a coleta de dados, as variáveis foram selecionadas e analisadas por meio de técnicas multivariadas, sendo utilizada a análise de Componentes Principais (ACP) e a análise de Classificação Hierárquica Ascendente (CHA). Foram analisadas variáveis relacionadas à produção e qualidade do leite, técnicas e práticas utilizadas no momento da ordenha, manejo alimentar, sistema de ordenha e variáveis sócio-culturais relacionadas ao produtor. As variáveis que melhor explicaram as diversidades das ACP foram as relacionadas com as práticas higiênico-sanitária (pré e pós-dipping, utilização dos detergentes alcalino e ácido na higienização, testes para detecção de mastite) realizadas na ordenha, com a composição de leite e vinculadas ao produtor (idade, escolaridade, tempo na atividade). Foi verificado que o uso destas práticas podem auxiliar para melhorar a produção e qualidade do leite, assegurando uma matéria-prima com maior valor comercial. O agrupamento dos sistemas de produção permitiu verificar a existência de grande diversidade entre as formas de produção, possibilitando identificar os fatores que podem influenciá-lo, a fim de formar estratégias que possam resultar ganhos em produção e qualidade do leite
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Cheng, Chin-Min. « Leaching of coal combustion products field and laboratory studies / ». Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1133195856.
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Yu, Deyue. « Identification, caractérisation, et expression de nouveaux gènes chez Arabidopsis thaliana ». Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10102.
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Nous avons participe au sequencage systematique du genome transcrit (etiquette de cdna) d'arabidopsis thaliana. Premierement, nous montrerons des donnees realises dans notre laboratoire et discuterons des interets. Deuxiemement, nous presenterons la caracterisation et l'expression de trois nouveaux clones de cdna. Le premier clone code pour un homologue d'un inhibiteur de proteinase (bowman birk). Le deuxieme clone code pour un homologue de la proteine a' du complexe snrnp u2. C'est le premier u2a' identifie dans le regne vegetal. Le troisieme clone code pour un homologue de la chaine alpha de succinyl-coa synthetase. La troisieme partie du travail concerne la caracterisation des clones correspondant aux genes fortement exprimes dans les boutons floraux. Trois clones de cdna ont ete caracterises representant deux familles divergentes de genes codant pour deux formes d'exopolygalacturonases. Cette divergence sera montree par les sequences et les expressions des genes correspondants. A la suite d'un criblage differentiel contre des cdnas de feuilles, un autre clone a ete isole. Ce clone code pour une proteine de reserve vegetatif. Le gene correspondant est fortement exprime dans les fleurs, les siliques, et les tiges. Dans les boutons floraux, les transcrits du gene sont localises dans les parois de carpelles
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Dias, Rogério de Matos. « Um modelo informacional para gestão de operações : o caso da Cia. Vale do Rio Doce - Depto. de Manganês e Ferro-Ligas ». reponame:Repositório Institucional do FGV, 2003. http://hdl.handle.net/10438/3880.
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Previous issue date: 2003This research aims to theoretically develop an informationaI modeI able to provide a fully integrated supply chain management for multiplant manufacturing companies, as well as to prove its feasibility in the field, using a combined action-research and case study investigation methodology for a representative mining&metals company - Cia. Vale do Rio Doce, Manganese and Ferroalloys Departament. The study also intends to describe how the proposed model can provide planning and control capabilities for the operational, tactical and strategic decision making leveIs, as result of the transational and managerial processes automatization, data analysis agility and increasing in the quality decision making processes. Moreover, the study also intends to describe the contributions of that informationaI model for the supply chain management in similar companies as well as to generalize the model's application for similar multiplant manufacturing companies.
Esta pesqUisa objetiva desenvolver, testar e demonstrar a aplicabilidade de um modelo infonnacional que possibilite a gestão integrada das operações da cadeia de suprimentos para indústrias geograficamente dispersas, também denominadas indústrias multi planta. Para tanto, serão aplicadas metodologias de estudo de caso e pesquisa-ação, em uma empresa representativa dos setores mineral e metalúrgico, o Departamento de Manganês e Ferro-Ligas da CVRD - Cia. Vale do Rio Doce. A pesquisa pretende demonstrar que o modelo de sistema infonnacional proposto, por meio da automatização dos processos transacionais e gerenciais, é capaz de prover recursos de planejamento e controle nos níveis operacional, tático e estratégico, devido a sua capacidade de incrementar a velocidade e a qualidade dos processos de análise e decisão. A pesquisa pretende conduzir, após análise dos resultados e avaliação das contribuições à empresa estudada, a um modelo informacional adequado para gerir as operações de outras empresas de mineração e metalurgia com características semelhantes.
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Abrão, Pedro Cesar Rodrigues Alves. « O uso de pozolanas como materiais cimentícios suplementares : disponibilidade, reatividade, demanda de água e indicadores ambientais ». Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-26032019-084557/.
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O cimento está entre os materiais mais utilizados no mundo moderno e sua produção deverá crescer nos próximos 40 anos. Esta crescente produção será responsável pela emissão de um grande volume de CO2 na atmosfera, atualmente a indústria cimenteira é responsável mundialmente por 10% das emissões totais de CO2 e pode chegar a 30% em 2050. Portanto, a academia e a indústria estão desenvolvendo estratégias para reduzir este impacto ambiental, uma dessas estratégias é a substituição do clínquer por materiais cimentícios suplementares (MCSs). Para esta estratégia ser efetiva é necessário que estes materiais possuam: (i) viabilidade econômica; (ii) disponibilidade e; (iii) viabilidade técnica. Hoje os materiais suplementares mais utilizados são a escória de alto forno e a cinza volante, mas o aumento na produção do cimento não foi acompanhado pela oferta destes materiais. Assim, outros materiais suplementares estão sendo utilizados pela indústria, como é o caso das pozolanas naturais e artificiais. Portanto o objetivo deste trabalho é estimar a disponibilidade e distribuição geográfica de alguns materiais cimentícios suplementares no Brasil e avaliar a eficiência de seis cimentos pozolânicos comerciais e compará-los com um cimento com alto teor de clínquer quanto a reatividade, demanda de água e indicadores ambientais. Todos os materiais foram fisicamente e quimicamente caracterizados; pastas e argamassas foram analisadas em termos de reatividade, demanda de água e resistência mecânica; finalmente, foram estimados indicadores ambientais e de eficiência. Para pastas e argamassas sem dispersante o cimento com alto teor de clínquer e aqueles com adição de terra diatomácea demandaram mais água que os demais para um mesmo espalhamento, já com adição de superplastificante o cimento REF foi o que demandou mais água. O cimento com alto teor de clínquer foi o mais reativo em todas as idades e apresentou os melhores resultados do indicador de fração de água combinada e indicador de intensidade de ligante. Já para o indicador intensidade de carbono os melhores resultados foram obtidos para os cimentos com alto teor de substituição. No entanto, o estudo mostra que a redução do teor de clínquer não está diretamente relacionada à redução do impacto ambiental do cimento em seu uso, esta redução de impacto também está associada com a eficiência do ligante quanto a sua reatividade e demanda de água.The cement is one of the most used materials in the modern world and its production should grow in the next 40 years. This growing production will be responsible for issuing a large volume of CO2 on the atmosphere, nowadays the cement industry is responsible worldwide for 10% of the total emissions of CO2 and it can reach 30% in 2050. Therefore, academia and industry are developing strategies to reduce this environmental impact, one of these strategies is the substitution of clinker by supplementary cementitious materials (SCMs). For this strategy to be effective it is necessary that these materials possess: (i) economic viability; (ii) availability and; (iii) technical feasibility. Today the most used supplementary materials are the blast furnace slag and fly ash, but the increase in the production of cement was not accompanied by the supply of these materials. Therefore, other supplementary materials are being used by the industry, as is the case of natural and artificial pozzolans. So, the aim of this work is to estimate the availability and geographic distribution of some supplementary cementitious materials in Brazil and evaluate the efficiency of six Portland pozzolan blended cements and compare them with a cement with high clinker content as to reactivity, water demand and environmental indicators. All materials were physically and chemically characterized; pastes and mortars were analyzed in terms of reactivity, water demand and mechanical strength; finally, environmental and efficiency indicators were estimated. For pastes and mortars without dispersant the cement with high content of clinker and those with the addition of diatomaceous earth ordered more water than the others to achieve the same spread, already with the addition of superplasticizer the cement REF was the one that ordered more water than the others. The cement with high clinker content was the most reactive in all ages and presented the best results of the binder efficiency indicator and binder intensity indicator. For the carbon intensity indicator, the best results were obtained for cements with high replacement content. However, the study shows that the reduction of the clinker content is not directly related to the reduction of the environmental impact of the cement in its use, this reduction is also associated with the binder efficiency in means of reactivity and water demand.
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Galand, Nicolas. « Extraction liquide-liquide de cations par des molécules complexantes : Simulations des ligands et des complexes à l'interface entre l'eau et une phase organique ou le CO2 supercritique ». Université Louis Pasteur (Strasbourg) (1971-2008), 2007. http://www.theses.fr/2007STR13191.
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Behm, Mariana Boneberger. « Síntese e avaliação de arranjos supramoleculares de triazenos monocatenados e complexos com os cátions Co3+, Cu2+, Ag+ e Au+ ». Universidade Federal de Santa Maria, 2010. http://repositorio.ufsm.br/handle/1/4196.
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Conselho Nacional de Desenvolvimento Científico e TecnológicoTriazenes ligands substituted by terminal aryl groups in the diazoamine chain [ N=N N(H) ] containing NO2 group substituted in different position and ortho C(O)NH2 on aryl ring was evaluated on the occurrence of intermolecular interactions through hydrogen links. The research was based primarily on X-ray diffraction in single crystal to analyze structurally the occurrence of self-assembles supramolecular architectures on solid state. This work presents the synthesis and investigation of molecular and crystal structure of eleven new compounds. The pre-ligands 1-(2-amidofenil)-3-(2-nitrofenil)triazeno (I), 1-(2-amidofenil)-3-(4-nitrofenil)triazeno (II) e 1-(2-amidofenil)-3-(3-nitrofenil)triazeno (III), the cobalt(III) complexes: {Co[C(O)NHC6H4NNNC6H4NO2](C2H8N2)2}{Cl}.CH3OH (1), {Co[C(O)NHC6H4NNNC6H4NO2](C2H8N2)2}{Cl}.H2O (2) and {Co[C(O)NHC6H4NNNC6H4NO2](NH3)4}{NO3}.H2O (3), and silver(I) complexes: {Ag[C(O)NH2C6H4NNNC6H4NO2](C2H8N2)}{[C(O)NH2C6H4NNN(H)C6H4NO2]} (4) and {Ag[C(O)NH2C6H4NNNC6H4NO2](C2H8N2)]} (5), and cupper(II) complexes: {Cu4[C(O)NHC6H4NNNC6H4NO2]2[(OCH3)4]} (6) and gold(I) complexes: {Au[C(O)NH2C6H4NNNC6H4NO2](PC18H15)}{C5H5N} (7) e Au[C(O)NH2C6H4NNNC6H4NO2](PC18H15)] (8). Other complementary techniques were used to characterize the compounds, such as: infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, ultraviolet-visible spectroscopy, mass spectrometry, Raman spectroscopy and thermogravimetric analysis.
Ligantes triazenos substituídos nos grupos arilas terminais na cadeia diazoamínica [ N=N N(H) ] contendo os substituintes NO2 em diferentes posições e o grupo C(O)NH2 orto substituído ao anel foram avaliados quanto à ocorrência de interações intermoleculares através de ligações de hidrogênio. A investigação baseou-se principalmente na difração de raios-X em monocristal para analisar estruturalmente a formação de arranjos supramoleculares no estado sólido. Este trabalho apresenta a síntese e a investigação da estrutura cristalina e molecular de onze compostos inéditos: os pré-ligantes 1-(2-amidofenil)-3-(2-nitrofenil)triazeno (I), 1-(2-amidofenil)-3-(4-nitrofenil)triazeno (II) e 1-(2-amidofenil)-3-(3-nitrofenil)triazeno (III), os complexos de cobalto (III): {Co[C(O)NHC6H4NNNC6H4NO2](C2H8N2)2}{Cl}.CH3OH (1), {Co[C(O)NHC6H4NNNC6H4NO2](C2H8N2)2}{Cl}.H2O (2) e {Co[C(O)NHC6H4NNNC6H4NO2](NH3)4}{NO3}.H2O (3), os de prata (I): {Ag[C(O)NH2C6H4NNNC6H4NO2](C2H8N2)}{[C(O)NH2C6H4NNN(H)C6H4NO2]} (4) e {Ag[C(O) NH2C6H4NNNC6H4NO2](C2H8N2)]} (5), o de cobre (II): {Cu4[C(O)NHC6H4NNNC6H4NO2]2[(OCH3)4]} (6) e os de ouro (I): {Au[C(O)NH2C6H4NNNC6H4NO2](PC18H15)}{C5H5N} (7) e Au[C(O)NH2C6H4NNNC6H4NO2](PC18H15)] (8). Outras técnicas complementares foram utilizadas para caracterizar os compostos, como: espectroscopia de infravermelho, ressonância magnética nuclear 1H, espectroscopia do ultravioleta visível, espectrometria de massa, espectroscopia Raman e análise termogravimétrica.
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Timmers, Luís Fernando Saraiva Macedo. « Estudos cristalográficos e aplicação da técnica de triagem virtual de ligantes para a busca de novos inibidores contra a enzima Citidina Deaminase (CDA ; EC 3.5.4.5) de Mycobacterium tuberculosis H37Rv ». Pontifícia Universidade Católica do Rio Grande do Sul, 2011. http://hdl.handle.net/10923/1295.
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Previous issue date: 2011The consumption has been a scourge of mankind since ancient times. This illness have been charged a high price in human lives, so many efforts have been made in order to defeat the Mycobacterium tuberculosis. The complete genomics sequence of Mycobacterium tuberculosis opened a new era and had a major impact in our understanding of this pathogen and also in research for microbial drugs. The researches could identify genes and later validate the metabolic pathways. The better understanding of metabolic pathways present in Mycobacterium tuberculosis corresponds to a first step and configures a possibility of identification of new molecular targets that could be derail the bacilli. However, there is much more to do, since of the discovery of rifampicin, a first-line drug used effectively against TB, none new chemotherapy has been released. TB is nowadays responsible for two million of deaths/year and is a global emergency which needs to be urgently repressed. The present work aim to realize structural analysis of the enzyme Cytidine Deaminase (CDA; EC 3. 5. 4. 5) from Mycobacterium tuberculosis associated with substrates and products, allying techniques such as molecular docking and dynamics simulations.
A tuberculose tem sido um flagelo da humanidade desde os tempos antigos. Esta doença tem cobrado um preço alto em vidas humanas, por esta razão muitos esforços tem sido feitos com o intuito de derrotar o Mycobacterium tuberculosis. A sequência genômica do Mycobacterium tuberculosis deu início a uma nova era e foi de grande impacto para o presente conhecimento deste patógeno como também na pesquisa de drogas anti-microbiais. Com estes avanços foi possível identificar genes e mais tarde validar vias metabólicas. O melhor entendimento das vias metabólicas presentes no Mycobacterium tuberculosis corresponde ao primeiro passo e configura uma possibilidade de identificação de novos alvos moleculares que possam erradicar o bacilo. Entretanto, ainda há muito a fazer, desde a descoberta da Rifampicina, a droga de primeira linha efetivamente utilizada contra TB, nenhuma nova droga quimioterápica foi identificada. Nos dias de hoje, a TB é responsável pela morte de dois milhões de pessoas por ano, sendo considerada uma emergência global, a qual precisa ser urgentemente erradicada. O presente projeto tem o objetivo de realizar a análise estrutural da enzima Citidina Deaminase (CDA; EC 3. 5. 4. 5) de Mycobacterium tuberculosis associada com seus substratos e produtos, aliando técnicas de Dinâmica e Docagem molecular.
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Timmers, Lu?s Fernando Saraiva Macedo. « Estudos cristalogr?ficos e aplica??o da t?cnica de triagem virtual de ligantes para a busca de novos inibidores contra a enzima Citidina Deaminase (CDA ; EC 3.5.4.5) de Mycobacterium tuberculosis H37Rv ». Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2011. http://tede2.pucrs.br/tede2/handle/tede/5413.
Texte intégralRésumé :
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Previous issue date: 2011-03-25A tuberculose tem sido um flagelo da humanidade desde os tempos antigos. Esta doen?a tem cobrado um pre?o alto em vidas humanas, por esta raz?o muitos esfor?os tem sido feitos com o intuito de derrotar o Mycobacterium tuberculosis. A sequ?ncia gen?mica do Mycobacterium tuberculosis deu in?cio a uma nova era e foi de grande impacto para o presente conhecimento deste pat?geno como tamb?m na pesquisa de drogas anti-microbiais. Com estes avan?os foi poss?vel identificar genes e mais tarde validar vias metab?licas. O melhor entendimento das vias metab?licas presentes no Mycobacterium tuberculosis corresponde ao primeiro passo e configura uma possibilidade de identifica??o de novos alvos moleculares que possam erradicar o bacilo. Entretanto, ainda h? muito a fazer, desde a descoberta da Rifampicina, a droga de primeira linha efetivamente utilizada contra TB, nenhuma nova droga quimioter?pica foi identificada. Nos dias de hoje, a TB ? respons?vel pela morte de dois milh?es de pessoas por ano, sendo considerada uma emerg?ncia global, a qual precisa ser urgentemente erradicada. O presente projeto tem o objetivo de realizar a an?lise estrutural da enzima Citidina Deaminase (CDA; EC 3.5.4.5) de Mycobacterium tuberculosis associada com seus substratos e produtos, aliando t?cnicas de Din?mica e Docagem molecular.
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Buzolin, Ricardo Henrique. « Mechanical properties and corrosion behaviours of the as-cast ZK40 alloys modified with individual additions of CaO, Gd, Nd and Y ». Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-13012017-093623/.
Texte intégralRésumé :
The effect of individual additions of calcium oxide (CaO), Gd, Nd and Y was investigated on the microstructure, mechanical properties and corrosion resistance of the as-cast ZK40 alloy. The microstructural features were analised using optical, scanning and transmission electron microscopy, X-ray diffraction and Scanning Kelvin Atomic Probe Force Microscopy. The compressive and tensile behaviours of the as-cast alloys at room temperature were investigated. Electrochemical Impedance Spectroscopy, hydrogen evolution and weight loss under immersion in 0.5 wt.% NaCl solution were used to evaluate the corrosion behaviour. The results of the mechanical and corrosion tests were correlated with the microstructures. The 2 wt.% Gd addition enhanced the ductility, while the Nd addition resulted in deterioration in mechanical properties. The addition of 2 wt.% Gd and 1 wt.% Y resulted in the improvement of the ductility. The addition of CaO did not affect the mechanical properties while the 2 wt.% Nd deteriorate it. The 1 wt.% Y addition enhanced the ductility. The CaO addition did not caused enhancement in mechanical properties. The corrosion behaviour was enhanced with the addition of CaO and Gd. The modification of ZK40 with Gd opens up new perspectives in the development of Mg-Zn based alloys.O efeito da adição individual de óxido de cálcio (CaO), Gd, Nd e Y foi investigado na microestrutura, propriedades mecânicas e resistência à corrosão de ligas ZK40 fundidas. As características microestruturais foram analisadas via microscopia óptica, microscopia eletrônica de varredura, microscopia eletrônica de transmissão, difração de Raios-X e \"Scanning Kelvin Atomic Probe Force Microscopy\". O comportamento à compressão e à tração das ligas à temperatura ambiente foi investigado. Espectroscopia eletroquímica de impedância, evolução de hidrogênio e ensaios de imersão em solução de 0.5% em peso de NaCl foram utilizados para avaliar a resistência à corrosão. Os resultados dos ensaios mecânicos e corrosão foram relacionados com a microestrutura. A adição de 2% em peso de Gd melhorou a ductilidade, ao passo que a adição de Nd resultou na piora das propriedades mecânicas. A adição de 2% em peso de Gd e 1% em peso de Y resultou na melhora da ductilidade. A adição de 1% em peso de Y causou uma melhora na ductilidade e a adição de CaO não teve impacto benéfico nas propriedades mecânicas. A resistência à corrosão foi melhorada com a adição de CaO e Gd. A modificação da liga ZK40 com a adição de Gd abre novas perspectivas no desenvolvimento de ligas Mg-Zn.
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Shokouhfar, Nasrin. « Synthèse et caractérisation de nouvelles armatures métal-organique à base de zirconium à partir de ligands carboxylates et étude de leur application dans l'adsorption et la détection des pollutions de l'eau et la capture et la conversion du CO2 et N2 ». Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILN058.
Texte intégralRésumé :
Cette thèse porte sur la synthèse et la caractérisation de cadres métallo-organiques (MOF) à base de Zr et leurs applications dans le traitement de l'eau et la production de carburant solaire. Les MOF sont des matériaux poreux composés d'ions métalliques et d'éléments de liaison organiques qui présentent des structures et des fonctionnalités ajustables. Ces propriétés les rendent aptes pour diverses applications, telles que le stockage de gaz, la catalyse, la détection, l'administration de médicaments, etc.Le traitement de l'eau consiste à éliminer les contaminants de l'eau afin de la rendre propre et sans danger pour l'homme. L'un des principaux contaminants de l'eau sont les colorants, largement utilisé dans les industries du textile, du papier et du cuir. La pollution par les colorants peut entraîner de graves problèmes pour la vie aquatique, la santé humaine et la qualité esthétique de l'eau. Pour éliminer les colorants de l'eau, nous avons synthétisé un nouveau Zr-MOF appelé TMU-66, qui a une forme de sphère creuse et un groupe fonctionnel N-oxyde. TMU-66 peut adsorber efficacement et sélectivement les molécules de colorant par le biais de diverses interactions, telles que les interactions électrostatiques, l'empilement π-π et la liaison de coordination. TMU-66 a présenté une capacité d'adsorption de 472 mg/g pour le colorant rouge Congo à un pH de 6,8 et à 25 °C, une des valeurs les plus élevées obtenues jusqu'à présent pour des adsorbants à base de MOF.La production de combustibles solaires est le processus de conversion de l'énergie solaire en combustibles chimiques qui peuvent être stockés et utilisés ultérieurement. L'un des carburants les plus prometteurs est l'ammoniac (NH3), qui peut être produit à partir d'azote (N2) et d'eau (H2O) en utilisant l'irradiation solaire comme source d'énergie. Ce processus est appelé photoréduction de N2 ou fixation photocatalytique de l'azote. Cependant, ce processus est difficile car N2 est très stable et difficile à décomposer. Nous avons modifié un autre Zr-MOF, appelé MOF-808, en introduisant un groupe nitro dans le linker organique. Cette structure modifiée peut absorber la lumière visible et transférer des électrons aux molécules de N2. Nous avons également combiné le MOF-808/NIP avec un autre matériau, le g-C3N4, pour améliorer l'absorption de la lumière et le transfert d'électrons. Le composite ainsi obtenue, MOF-808/NIP@g-C3N4, peut produire jusqu'à 490 μmol d'ammoniac par gramme de composite et par heure sous irradiation visible.En résumé, les objectifs de ce travail de thèse étaient d'étudier le potentiel des MOF pour deux applications distinctes, en utilisant une approche conceptuelle qui intègre l'ingénierie de la bande interdite, la modulation de la structure et les matériaux composites à hétérojonction. Les résultats ont révélé que les MOF peuvent adsorber les impuretés de l'eau et fonctionner comme des photocatalyseurs pour produire de l'ammoniac grâce à la photoréduction de N2 sous irradiation visible. Les résultats obtenus ouvrent des perspectives très intéressantes dans le domaine de traitement de l'eau polluée et de production d'ammoniac. Ces technologies sont cruciales pour sauvegarder notre planète et garantir un avenir stableThis thesis investigates the synthesis and characterization of Zr-based metal-organic frameworks (MOFs) and their applications in water treatment and solar fuel production. MOFs are porous materials composed of metal ions and organic linkers that exhibit tuneable structures and functionalities. These properties make them suitable for various applications, such as gas storage, catalysis, sensing, drug delivery, etc.Water treatment is the process of removing contaminants from water to make it safe and clean for human use. One of the main contaminants in water are dyes, which are widely used in the textile, paper, and leather industries. Dye pollution can cause serious problems for aquatic life, human health, and aesthetic quality of water. To remove dyes from water, we synthesized a new Zr-MOF called TMU-66, which has a hollow sphere shape and an N-oxide functional group. TMU-66 can efficiently and selectively adsorb dye molecules through various interactions, such as electrostatic attraction, π-π stacking, and coordination bonding. TMU-66 exhibited and adsorption capacity of 472 mg/g for Congo red dye at pH 6.8 and 25 °C, one of the highest values achieved for MOF-based adsorbents so far.Solar fuel production is the process of converting solar energy into chemical fuels that can be stored and used later. One of the most promising fuels is ammonia (NH3), which can be produced from nitrogen (N2) and water (H2O) using sunlight as the energy source. This process is called N2 photoreduction or photocatalytic nitrogen fixation. However, this process is challenging because N2 is very stable and difficult to break apart. We modified another Zr-MOF called MOF-808 by adding a nitro group to its linker. The modified framework is able to absorb visible light and transfer electrons to N2 molecules. We also combined MOF-808/NIP with another material called g-C3N4, which can enhance light absorption and electron transfer. The resulting composite, MOF-808/NIP@g-C3N4, can produce up to 490 μmol ammonia per gram of composite per hour under visible light and ambient conditions.In summary, the objectives of this thesis work were to investigate the potential of MOFs for two distinct applications, utilizing a conceptual design approach that incorporated bandgap engineering, structure modulation, and heterojunction composite materials. The findings revealed that MOFs can absorb water impurities and function as photocatalysts to achieve ammonia production through solar-powered N2 photoreduction. This breakthrough has the potential to foster the creation of more effective and environmentally conscious technologies that tackle worldwide water pollution and ammonia production issues. These technologies are crucial in safeguarding our planet and guaranteeing a stable future
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Brunel, Paul. « Complexes pince et cooperativité métal/ligand : application en catalyse ». Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30275/document.
Texte intégralRésumé :
Ce travail de thèse porte sur la chimie organométallique des complexes pince indényle/indénediide de palladium et de platine et leurs applications en catalyse coopérative métal-ligand. Le premier chapitre de ce manuscrit fait un point bibliographique non-exhaustif du domaine de la coopérativité métal-ligand, des travaux de Noyori sur l'hydrogénation asymétrique, jusqu'aux récents travaux de Milstein avec les ligands désaromatisés. Les ligands pince sont également présentés. Du premier exemple PCP décrit par Shaw jusqu'au CNC développé par Bezuidenhout. La versatilité de ces ligands est illustrée à travers quelques modifications permettant des réactivités originales ou l'isolation d'espèces hautement instables. Le second chapitre présente une nouvelle réaction de formation de cycle avec le complexe pince indénediide de palladium. Cette réaction implique pour la première fois deux molécules de substrat, le CO2 comme source C1 et les propargylamines/homopropargylamines. L'étude mécanistique du système a permis d'établir l'implication de la coopérativité métal-ligand. Ensuite, le troisième chapitre est un chapitre de chimie exploratoire. De nouvelles réactivités ont été étudiées avec les complexes pince de platine. L'activation de liaisons peu polaires telles que H-H et H-Si ont permis la réduction de liaisons insaturées. Les propositions mécanistiques, qu'il reste à confirmer, semblent indiquer que les métathèses ?, ainsi que les insertions migratoires, sont possibles avec ces complexes. Finalement, le dernier chapitre est consacré au développement d'un nouveau ligand pince ayant la particularité d'être hémilabile et ouvrant ainsi la voie à de nouvelles réactivités. Sa coordination au palladium, ainsi que la déprotonation de ce dernier, a permis le développement d'un complexe coopératif qui a été testé en cycloisomérisation. L'ensemble de ces travaux reflètent l'importance des ligands pince indényle/indénediide et de la coopérativité métal-ligand en catalyseThis Ph.D. work deals with organometallic chemistry of indenyl/indenediide palladium and platinum pincer complexes and their applications in metal-ligand cooperative catalysis. The first chapter of this manuscript compiled a non-exhaustive bibliographic survey of the field of metal-ligand cooperation, from Noyori's system applied to the asymmetric hydrogenation, to the recent examples described by Milstein involving non-aromatic pincer ligands. Pincer ligands are also presented. Starting from the first example, in which Shaw shed light a PCP pincer, to the contemporary CNC pincer reported by Bezuidenhout. The versatility of those ligands is illustrated through few modulations allowing originals reactivities or stabilisation of highly unstable species. The second chapter is focused on the development of a new catalytic reaction with the indenediide palladium pincer complex. This reaction entail, for the first time, two substrates, the CO2 as a C1 source and propargylamines/homopropargylamines. The mechanistic studies turn out the importance of the metal-ligand cooperativity. Then, the third chapter concerns exploratory chemistry. New reactivities have been studied with the platinum complexes. The activation of low polar bond such as H-H and H-Si allowed the reduction of unsatured C-C bond. The mechanistic propositions, that remain to be confirmed, seem to indicate the feasibility of ? bond metathesis and migratory insertions. Finally, the last chapter is dedicated to the development of a new ligand. The latter showed the distinctive characteristic to be hemilabile, leading the way of new reactivities. His coordination to palladium, followed by his deprotonation to give rise to the non-innocent nature of the complex is presented, as well as the application of the resulting complex in the context of a cycloisomerisation. Those results are reflecting the importance of the indenyl and indenediide pincer ligands besides the metal-ligand cooperativity in catalysis
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Imolorhe, Ijeme. « FUNCTIONAL CHARACTERIZATION OF TWO PHENYLACETYL-COA LIGASES IN BURKHOLDERIA CENOCEPACIA ». 2012. http://hdl.handle.net/1993/5081.
Texte intégralRésumé :
Burkholderia cenocepacia causes Cepacia syndrome, a fatal pneumonia that affects Cystic Fibrosis patients. Aromatic degradation has been linked to virulence in B. cenocepacia by insertional mutagenesis of genes involved in phenylacetic acid catabolism. B. cenocepacia has two paralogous copies of PaaK, the phenylacetyl-CoA ligase, which produces PA-CoA, the inducer of the pathway. Our objective was to assess a role for PaaK1 and PaaK2 in PA metabolism and virulence by constructing clean deletion mutants for each gene, and a double paaK mutant, as well as to quantify virulence using the nematode host model. Deletion and complementation of paaK1 revealed no change in killing phenotype. Reporter activity assays revealed PaaK1-dependent induction of the PA pathway 3-hydroxyphenylacetic acid but not 4-hydroxyphenylacetic acid. Altogether, these results demonstrate that 3-OHPA induces the PA degradation pathway in a paaK1 dependent manner and that PaaK1 is not involved in pathogenicity.
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Allina, Sandra Mary. « Phenylpropanoid metabolism in poplar : characterization of the 4-coumarate : CoA ligase gene family and a putative hydroxycinnamoyl-CoA thioesterase ». Thesis, 1999. http://hdl.handle.net/2429/9827.
Texte intégralRésumé :
The work presented in this thesis is part of a larger study designed to examine the
possibility of altering lignin content and/or composition by genetic engineering. Hybrid
poplar was used as a model tree system. Lignin precursors (cinnamyl alcohols) are derived
from phenylpropanoid metabolism. 4-coumarate:CoA ligase (4CL) activity is required for the
activation of hydroxycinnamic acids prior to their being fed into the lignin specific branch
pathway. The purpose of this research was to test the hypothesis that multiple genes encode
4CL isoforms that are differentially expressed and preferentially utilize one or more
methoxylated hydroxycinnamic acid substrate.
4CL is encoded by a gene family in hybrid poplar. Two full-length cDNA clones
(4CL-216 and 4CL-9) representing two different genes (4CL1 and 4CL2) were isolated from
a young leaf library and characterized. Southern blot analysis demonstrated that other 4CL
genes exist in the poplar genome. Northern blot analysis demonstrated that 4CL1 and 4CL2
are differentially expressed. 4CL1 is preferentially expressed in old leaves, while 4CL2 is
preferentially expressed in young leaves. Neither gene is expressed at high levels in
developing xylem and they may not play a major role in lignification of this tissue.
The 4CL cDNA clones were expressed in a insect cell/baculovirus system. Partially
purified recombinant 4CL proteins were tested for substrate preference. Both of the
recombinant 4CL proteins used hydroxycinnamic acid substrates in a similar manner. The
substrate preferences were similar to those found for each of the partially purified native 4CL
isoforms (Allina et al., 1998). This suggests that 4CL isoforms with large differences in their
substrate utilization profiles do not, in fact, exist in poplar.
The recombinant 4CL proteins use cinnamic acid while the native proteins do not. It
was hypothesized that a cellular factor was responsible for modifying native 4CL such that it
could no longer use cinnamic acid as a substrate. However, the results of this study strongly
suggest that 4CL activity is not being modified but rather, that a thioesterase activity is
responsible for the observed phenomena. The thioesterase is able to use all
hydroxycinammoyl-CoA thioesters as substrates. This was previously masked by the fact that
recombinant 4CL could convert most hydroxycinnamic acids to hydroxycinnamoyl-CoA
thioesters faster than the thioesterase could perform the reverse reaction. The possible role of
a hydroxycinnamoyl-CoA thioesterase in phenylpropanoid metabolism is discussed.
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Hung, Mao-Sen, et 洪茂森. « Phylogeography of Abies kawakamii (Hayata) Ito based on 4-coumarate CoA ligase gene ». Thesis, 2004. http://ndltd.ncl.edu.tw/handle/76773225149029429005.
Texte intégralRésumé :
碩士國立臺灣大學
植物科學研究所
92
Population genetic structure and phylogeographical relationships of Abies kawakamii (Hayata) Ito in Taiwan were studied by analyzing the DNA sequence of 4- coumarate CoA: ligase (4CL, 1174 bp). Samples were collected from eight alpine populations: Kuanshan, Yushan, Chilaishan, Hohuanshan, Nanhutashan, Tapachienshan, Tahsuenshan, and Wumingshan. Two clones of 4CL gene from each individual were sequenced. From a total of 135 DNA sequences of 68 individuals, 4CL can be separated into two gene family: 4CL1 and 4CL2. One of the gene, 4CL1 containing 88 sequences was further studied. The DNA fragment of 4CL1 consisted of five exons and four introns. The total length of intron was 380 bp, and contained 65 polymorphic sites: 60 point mutations and five insertions, giving a total of 71 haplotypes. The genealogical trees generated from these four introns showed similar pattern. Most of the sequences of each intron belonged to ancestral haplotype and derived haplotype, and many unique terminal haplotypes. Populations shared ancestral haplotype, derived haplotype, and the unique terminal haplotypes. These populations were retreating to higher altitude, experiencing an effect of bottleneck and genetic drift resulting in the composition of haplotype mentioned above that could characterize the refuge populations. Based on the average values of parameters of population differentiation, FST and KST, and population divergence DXY, we found that Tahsuenshan, Yushan, Wumingshan, and Chilaishan had the highest values indicating the possible major region of refugia for Abies kawakamii. According to 4CL1 DNA sequence and the morphology of seed, neither A. homolepis nor A. mariesii of Japan is ancestral to A. kawakamii. In terms of number of loci of 4CL1 gene, we found six loci among 16 in the gametophyte. These 4CL1 DNA sequences were very similar and only exhibited single nucleotide polymorphism.
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Cukovic, Daniela. « Cloning and expression of genes encoding divergent 4-coumarate : CoA ligase in poplar ». Thesis, 1999. http://hdl.handle.net/2429/9442.
Texte intégralRésumé :
The enzyme 4-coumarate:Coenzyme A ligase catalyzes the third and final step in the
general phenylpropanoid metabolic pathway, providing activated thioester substrates for
different phenylpropanoid products. To clone putative divergent members of the poplar 4CL
gene family, degenerate primers directed to a part of the first exon, containing a putative
AMP-binding motif, were used. Three new 4CL-like classes were distinguished among 72
cloned PCR amplification products. The new 4CL-like sequence classes, arbitrarily named
4CL6, 4CL10 and 4CL14, shared 61% to 96% deduced amino acid sequence identity over
the 600 bp region compared. A full-length cDNA clone of 4CL6 was isolated by screening a
xylem cDNA library with the PCR fragment. Isolation of a full-length cDNA clone of
4CL10 involved both screening a young leaf cDNA library, and 5' and 3' RACE. Sequence
analysis showed that the most divergent member of the poplar 4CL gene family is 4CL10
(61% -65% amino acid identity with others), while 4CL6 is moderately divergent to
previously isolated members. RNA blot analysis showed that the 4CL6 gene is expressed
exclusively in xylem, green stem and root, while 4CL10 expression is restricted to young
leaf, old leaf and root. Recombinant enzymes corresponding to the 4CL6 and 4CL10 genes
were expressed using a baculovirus system. The recombinant 4CL6 was partially purified
by FPLC, and showed a substrate utilization profile (4-coumaric acid > ferulic acid > caffeic
acid > cinnamic acid, and no activity toward sinapic acid) similar to the profiles of the
previously studied native and recombinant 4CL proteins.
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Law, Adrienne. « Structural and functional characterization of PaaK1 & ; PaaK2 : phenylacetate CoA ligase paralogs from Burkholderia cenocepacia J2315 ». Thesis, 2010. http://hdl.handle.net/1828/3613.
Texte intégralRésumé :
Aromatic compounds comprise approximately 25% of the Earth`s biomass. Accordingly, turnover of these thermostable compounds is essential to the biogeochemical carbon cycle. Specialized microbial enzymatic pathways are largely responsible for mineralization of aromatic compounds, and are extensively studied for bioremediation purposes. The phenylacetic acid degradation pathway (PAA) is of particular interest as it is utilized for degradation of a multitude of aromatic compounds, including environmental pollutants, and appears to be widely distributed among bacteria. Intriguingly, the PAA pathway has also been implicated as a virulence factor in the cystic fibrosis pathogen, Burkholderia cenocepacia. As such, detailed biochemical characterization of the PAA pathway holds great potential for improving bioremediation strategies for aromatic pollutants, as well as understanding carbon source utilization during B. cenocepacia infection.
A striking feature of the PAA pathway in B. cenocepacia is the presence of two genes encoding the phenylacetate CoA ligase (PCL) enzyme (paaK1 and paaK2), responsible for the initial CoA activation of phenylacetic acid. PCLs are members of the adenylate forming enzyme superfamily. However, sequence alignments reveal several intriguing features, including a potentially novel microdomain consisting of the initial ~80 N-terminal residues, which possesses percent identity to any structurally characterized family member. Furthermore, this superfamily utilizes a complicated catalytic mechanism, exploiting several conserved motifs during the reaction process. The precise roles of many key conserved residues are not yet well understood, especially during the pre-adenylation, ATP bound state, for which few high quality crystal structures exist.
In order to define the early stages of the catalytic mechanism, and to assess how the divergent polypeptide region may impact the PaaK enzymes, we have pursued a detailed structural characterization of the paralogs, complemented with functional assessments. Specifically, we have produced a 1.6 Å resolution crystal structure of PaaK1 in complex with ATP, which reveals a novel helical bundle arrangement at the N-terminal domain never before seen in this superfamily. Remarkably, homodimerization of PaaK1 appears to reconstitute potentially important β sheet interactions observed in the classical N-terminal arrangement of family members. Moreover, our structure is one of few which contain well ordered β and γ phosphates, allowing for detailed examination of significant protein-ATP interactions with conserved catalytic residues.
To better comprehend the roles of these residues over the course of the reaction, we have produced additional crystal structures of PaaK1 and PaaK2 in complex with the phenylacetyl adenylate intermediate. Notably, PaaK2 was captured following the domain reorientation, poised to catalyze thioesterification of phenylacetyl adenylate, providing insight into the later stages of the reaction process. Furthermore, the intermediate co-structures divulge the location of the aryl substrate binding pocket for both paralogs. Detailed comparisons of the binding pockets accompanied kinetic characterizations for both paralogs, demonstrating that PaaK2 possesses an apparent KM of 150 μM for phenylacetic acid, more than double that of PaaK1 (62 μM). Our findings provide preliminary evidence for distinct functional roles of the PaaK paralogs in B. cenocepacia, while imparting additional insight into catalytic roles of conserved residues within the adenylate forming superfamily at large.Graduate
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Rodriguez, Studart-Guimarães Claudia [Verfasser]. « Functional analysis of the role of succinyl CoA ligase in the photosynthetic metabolism of tomato / by Claudia Rodriguez Studart-Guimarães ». 2006. http://d-nb.info/982292066/34.
Texte intégral
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Tsai, Hui-Ju, et 蔡蕙如. « Molecular Cloning and Expression of Resveratrol -related Biosynthesis of cinnamate 4-hydroxylase, 4-coumaroyl-CoA ligase and stilbene synthase from Vitis vinifera ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/w2q7dg.
Texte intégral
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Chien-Te, Ho, et 何建德. « Synthesis and Characterization of Coordination Polymers via the Self-assembly of Metal Ions (Co2+, Zn2+, Cd2+), Anionic Ligands (fumarate, isonicotinate, (+, -)tartrate) and Neutral Ligands (4,4-bipy, trans-bpe) ». Thesis, 2001. http://ndltd.ncl.edu.tw/handle/64329972598420078519.
Texte intégralRésumé :
碩士國立中正大學
化學研究所
89
Seven novel organic-inorganic coordination polymers: Zn(fumarate)(4,4’-bipy)2 (1), [Co(4,4’-bipy)(H2O)4](fumarate)‧4H2O (2), Cd(fumarate)(4,4’-bipy) (3), Cd(isonicotinate)2(trans-bpe)0.5(H2O) (4), [Co(L(+)-tartrate)(4,4’-bipy)(H2O)]2‧(4,4’-bipy) (5) , [Co(D(-)-tartrate)(4,4’-bipy)(H2O)]2‧(4,4’-bipy) (6) and Cd3(NO3)2(isonicotinate)4(4,4’-bipy)2(H2O)2 (7) ( 4,4’-bipy = 4,4’-bipyridine, trans-bpe = trans-1,2-bis(4-pyridyl)-ethylene), were synthesized by pseudo -hydrothermal synthesis and characterized by X-ray crystallographic techniques. (1) crystallizes in monoclinic space group C2/c with a = 18.802(3) Å, b = 10.091(2) Å, c = 14.371(4) Å, β= 125.91(1)°,V = 2208.4(8) Å3. (2) crystallizes in triclinic space group P-1 with a = 7.060(1) Å, b =7.851(2) Å, c = 9.803(1) Å, α= 79.51(1)°, β= 86.63(1)°, γ= 72.59(2)°, V=507.5(2) Å3. (3) crystallizes in monoclinic space group C2/c with a =11.693(1) Å, b = 15.594(2) Å, c = 15.591(1) Å, β= 90.07(1)°, V = 2901.9(5) Å3. (4) crystallizes in triclinic space group P-1 with a = 9.647(1) Å, b = 9.664(1) Å, c = 11.143(2) Å, α= 104.79(1)°, β= 104.75(2)°, γ= 98.30(1)°, V=946.7(2) Å3. (5) crystallizes in monoclinic space group P21 with a = 11.4939(13) Å, b =9.6599(11) Å, c = 18.173(2) Å, β= 107.759(9)°, V = 1921.6(4) Å3. (6) crystallizes in monoclinic space group P21 with a = 11.495(2) Å, b = 9.6654(14) Å, c = 18.170(2) Å, β=107.724(10)°, V =1923.0(5) Å3. (7) crystallizes in monoclinic space group P21/n with a = 9.838(2) Å, b = 12.891(4) Å, c = 19.302(2) Å, β=90.57(2)°, V =2447.8(9) Å3. (1) consists of zigzag chains built up by [Zn(4,4’-bipy)2]2+ moieties linked by fumarate. The structure of (2) consists of one-dimensional chains built up by [Co(H2O)4]2+ units bridged by 4,4’-bipy, with one equivalent of fumarate located between the chains to balance the charge and four equivalents of uncoordinated water molecules. (3) adopts a three-dimensional framework, formed by Cd(fumarate) sheets cross-linked by 4,4’-bipy ligands. (4) is a three-dimensional framework, formed by [Cd(isonicotinate)2(H2O)] motifs cross-linked by 4,4’-bipy ligands. (5) and (6) are enantiomers, consisting of two-dimensional framework, formed by [Cd(tartrate)(H2O)] motifs linked by (4,4’-bipy) ligands, with one equivalent of uncoordinated 4,4’-bipy located between the two-dimensional framework. (7) has two Cd centers. Cd(1) is in a distorted pentagonal bipyrimidal coordination sphere while Cd(2) is in an octahedral environment. Cd(1) and Cd(2) are bridged by 4,4’-bipy and isonicotinate ligands, forming a three-dimensional framework. Their thermal stabilities and spectroscopic data are also reported in the thesis.