Literatura científica selecionada sobre o tema "Biocatalytique"
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Teses / dissertações sobre o assunto "Biocatalytique"
Giguère, Pascall. "Synthèse biocatalytique d'hétérocycles azotés". Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25847/25847.pdf.
Texto completo da fonteGatt, Etienne. "Etude de la déconstruction de résidus agricoles lignocellulosiques par extrusion biocatalytique". Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0006/document.
Texto completo da fonteBiocatalytic extrusion, also named bioextrusion, is a reactive extrusion technique using enzymes as catalysts. Bioextrusion is considered as a link between the previous physico-chemical pretreatment (like alkaline extrusion) and the subsequent enzymatic hydrolysis in batch conditions. The extrusion allows a continuous, flexible and versatile process for high consistency media, easily transferable to the industrial level. However, complexity of both lignocellulosic biomass and lignocellulolytic enzymes and their interactions during the extrusion process are underlined by the literature. Numerous response surface methodology experiments with starchy biomass indicate that bioextrusion efficiency is mainly influenced by substrate and enzymes loading. Enzymatic activity during the bioextrusion process of lignocellulosic biomass is confirmed by the experiments despite the mechanical constraints and the limited residence time. During bioextrusion, best holocellulosic fraction hydrolysis results were obtained with high substrate and enzymes loadings. Significant modifications of the solid fraction like particule size reduction, visual deconstruction of the biomass structure, increased sensibility to thermal decomposition and the evolution of the surface exposure of crystalline and amorphous cellulose were observed. Enzymatic hydrolysis of the bioextrdates is prolonged in batch conditions. Clear improvements of speeds and rates of sugars conversion up to 48 h indicate a long term influence of the bioextrusion. Gain observed are steady for the pretreated wheat straw whereas it increases with time for corn residues and birch barks. Post-extrusion, a negative influence of the substrate loading is measured. However, best enhancements for the glucose conversion of pretreated wheat straw are detected for high substrate and enzymes loadings. From 4 to 48 h, significant losses in xylose conversion are measured with previous bioextrusion. Indicators of the solid fraction deconstruction, observed during the bioextrusion step, indicate a stronger biomass degradation after 48 h. Improvements of glucose conversion rates can be associated with good mixing conditions of the extruder, especially due to the use of kneading elements. Enzymes are probably more homogeneously distributed (distributive mixing) and can access more catalytic sites available. Moreover, dispersive mixing limits the enzyme jamming due to the biocatalysts concentration. Extrusion process permits an better agitation efficiency, good mass transfer conditions and probably a higher contact between substrate and enzymes. Lower xylose conversion results may be attributed to non-specific adsorptions or inactivation phenomena due to mechanical constraints and lignin residues. Good deconstruction results on the solid fraction may be associable with a synergetic action between mechanical and biochemical constraints. Autofluorescent signal analysis of the lignin fraction show its evolution during the deconstruction of the solid residue. During the hydrolysis, a progressive production of very small particles, appearing to be associated with the lignin fraction is observed. Lignin-carbohydrate complexes are also detected in the liquid fraction. These heteropolymeric complexes, difficult or even impossible for the enzymes to hydrolyze, are an obstacle to the biomass valorization. If lignin deconstruction is mainly due to the alkaline pretreatment, bioextrusion process seems to reduce the proportion of these heteropylymers with high molecular weights
Marmillot, Philippe. "Études théoriques et expérimentales de structurations spatiales apparaissant dans un système biocatalytique compartimenté". Compiègne, 1990. http://www.theses.fr/1990COMPD303.
Texto completo da fonteEl, Housseini Wassim. "Réacteur biomimétique : compartimenter et coupler la régénération du cofacteur NAD(P)H et l’oxydation biocatalytique de l’hydrogène". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0160.
Texto completo da fonteThe regeneration of cofactors NADH and NADPH is an important topic in biotechnology because many redox enzymes, such as alcohol dehydrogenases, imine reductases, and P450 monooxgenases, require cofactor to deliver their redox equivalent. However, because cofactors are particularly expensive, supplying stoichiometric cofactor when these enzymes are used in chemical synthesis is not economically feasible. To address this issue, a number of cofactor regeneration systems have been developed. Traditional regeneration systems for reduced cofactors have drawbacks because most of them require a carbon-based sacrificial co-substrate reductant and produce a by-product that is likely to be burned as waste, impeding downstream product purification and lowering the atom economy.In this work, the implementation of redox biocatalysis in a flow reactor coupling separately hydrogen oxidation to NADH regeneration was developed. A hierarchization of the work was important in order to proceed with an efficient regeneration of NADH.First, in a redox flow bioreactor hybridized by a gas diffusion electrode for hydrogen oxidation, the electrochemically mediated regeneration of NADH by a dissolved Rhodium complex ([Cp*Rh(bpy)Cl]+) was implemented. Initially, the reactor was optimized in terms of concentrations of rhodium complex and NAD+ ([NAD+]/[Cp*Rh(bpy)Cl]+ = 40), the non-humidification of hydrogen gas, the flow rates of H2 gas and electrolytic solution (20 mL.min-1), and the pH of the solution (7.2).Secondly, in order to promote the best cycling of both the catalyst and the enzymatic cofactor and potentially easier purification of the synthesized molecules, the immobilization of the rhodium complex was proceeded on a carbon paper coated with MWCNT (Rh@CP-MWCNT). Rh@CP-MWCNT electrode was shown to be stable for periods of more than 5 days under flow conditions. Following that, the cofactor regeneration technique was applied to NADH-dependent biosynthesis using L-lactate dehydrogenase (LDH): the enzyme was immobilized on a separate layer placed approximately 50 µm from the Rh-CP-MWCNT matrix, and used in the flow cell. A cofactor concentration as low as 10 µM was found to be sufficient for the conversion of pyruvate with high faradaic efficiency (78 %) and total turnover number (TTN) levels of 1.8*104, 2.5*103, and 1.8*105 for the Rh complex, the NADH cofactor, and the LDH enzyme, respectively.On the other hand, to expand the study, chemical catalysts were exchanged by biological ones. FNR, Ferredoxin NADP+ reductase, replaced the Rh complex at the cathodic compartment
Baud, Damien. "Oxydation biocatalytique de liaison C-H non activée pour la synthèse de dérivés bêta-hydroxylamines : application à la synthèse d'acides aminés non protéinogènes". Thesis, Evry-Val d'Essonne, 2013. http://www.theses.fr/2013EVRY0020/document.
Texto completo da fonteThe work described in this manuscript deals with the search of new members of the α-ketoglutarate and Iron-dependent dioxygenases family (α-KAO) and their applications in organic synthesis. The first part of this work presents the search of new enzymes through a genomic approach based on sequence homology and InterPro motif sharing. Two high-throughput screenings with 79 and 127 candidate enzymes have been performed on 23 and 36 substrates more or less structurally close to known metabolic substrates. 8 new α-KAOs have been discovered. Among these new enzymes, four were studied in more details. After optimization of the enzymatic reaction conditions for each enzyme, scale-up allowed to obtain compounds for isolation and characterization. With these four enzymes, (3S)-3-hydroxy-L-lysine, (4R)-4-hydroxy-L-lysine as its cyclic derivative, (3S)-3-hydroxy-L-ornithine and a derivative of (3S)-3-hydroxy-L-arginine were produced. Two of the new α-KAO were combined in a cascade process to afford the (3R,4R)-3,4-dihydroxy-L-lysine as its cyclic derivative. We proposed a biocatalytic synthesis of mono and hydroxydiamines by coupling one or two α-KAO with a decarboxylase enzyme. (2S)-1,5-diamino-2-pentanol, 1,5-diamino-3-pentanol, (2S)-1,4-diamino-2-butanol and (2S,3S)-1,5-diamino-2,3-pentanediol were obtained with good overall conversions
Attolini, Mireille. "Préparation de 3-acétoxy cycloalcen-1-yl phosphonates de dialkyle par acétoxylation catalysée par les sels de palladium. Synthèse enantiosélective par voie biocatalytique". Aix-Marseille 3, 2000. http://www.theses.fr/2000AIX30022.
Texto completo da fonteGuedidi, Sadika. "Elaboration de membranes biocatalytiques par immobilisation d'enzyme dans des couches de polyélectrolytes". Montpellier 2, 2009. http://www.theses.fr/2009MON20195.
Texto completo da fonteThe objective of this work is to study the enzyme immobilization on membrane materials by using the technique of deposit of polyelectrolyte multilayers. For that purpose, we used two enzymes with different size and charge, trypsin and urease, to study the role of the location of enzymes in the material (surface modification or into the pores). The storage stability was studied and showed that the immobilization of enzymes into the layers of polyelectrolytes improves their stability in a very significant way. Two techniques of membrane separation, the ultrafiltration and the diffusion, were used to understand the mechanisms occurring during the transport of solutes. These results showed the importance of time of residence near the enzyme by the competition between the reaction and the filtration. The structural variation of the trypsin was investigated by fluorescence spectroscopy and fluorescence anisotropy
Benilova, Iryna. "Approche "biocapteur" pour sonder la bioaffinité et les interactions biocatalytiques de petits xénobiotiques". Ecully, Ecole centrale de Lyon, 2007. http://bibli.ec-lyon.fr/exl-doc/ibenilova.pdf.
Texto completo da fonteNowadays, bioelectronics becomes a discipline with prominent biomedical and pharmacological potential. Investigations reported in this manuscript are focused on the use of label-free electrochemical and optical biosensors for the study of bioaffinity and biocatalytic interactions of some small xenobiotics (odorants and steroid glycoalkaloids) with immobilized macromolecules, namely, G protein-coupled human olfactory receptor OR 17-40 and cholinesterases from human and equine serum. The butyryl cholinesterases immobilized on pH-sensitive field-effect transistors follow Michaelis kinetics of hydrolysis of their substrates. Glycoalkaloids α-solanine, α-chaconine and tomatine inhibit the equine enzyme reversibly and competitively while for the human cholinesterase a mixed mode of reversible inhibition is suggested. α-Chaconine is the most potent inhibitor of both enzymes. The affinity interactions of glycoalkaloids and equine butyryl cholinesterase have been probed with electrochemical impedance spectroscopy. The absence of enzymatic substrate can significantly improve label-free detection of weak and competitive inhibitors (α-solanine). Olfactory receptor OR 17-40 has been successfully employed as odorant-recognition part of impedimetric and surface plasmon resonance-based platforms. Possibility of direct monitoring molecular events trigeered by agonist-stimulated receptor is the first step towards the "biolectronic nose"
Jacopini, Sabrina. "Utilisation de la 13-Hydroperoxyde lyase recombinante d’olive dans des procédés biocatalytiques de production de composés à note verte". Thesis, Corte, 2015. http://www.theses.fr/2015CORT0016/document.
Texto completo da fonteThe hydroperoxide lyase (HPL) derives from a metabolic pathway named lipoxygenase pathway widely represented in plants and involved in the production of flavoring compounds (hexanal, 3Z-hexenal and 2E-hexenal). These volatile compounds are responsible for the fresh odor of cut grass known as "green note" and have a particularly interest for flavor and food industries. Their biosynthesis results from the oxygenation of linoleic and linolenic acids by lipoxygenase action to form fatty acid hydroperoxides, then of their cleavage by hydroperoxide lyase action. The processes of production currently used are highly polluting or lead to a low yield. To overcome these drawbacks, the use of recombinant enzymes in such processes constitutes an attractive alternative because they would allow producing these molecules in a more effective way, while benefiting from the "natural" label.A cDNA encoding for HPL (HPLwt) from black olive fruit was isolated, and in order to improve the enzyme solubility, the HPL deleted of its chloroplast transit peptide (HPLdel) was then produced. Both enzymes were expressed into E. coli (M15), purified by affinity chromatography, and characterized. They act exclusively on 13-hydroperoxide (13-HPL) and display an optimum pH at 7.5 and an optimum temperature at 25 °C. The bioconversion of 13-hydroperoxides of linoleic and linolenic acids in hexanal and 3Z-hexenal respectively, using HPLwt or HPLdel was studied. Conversion yields reach a maximum of 93 % and 68 % for hexanal production, and 73 % and 45 % for 3Z-hexenal when reactions were performed by HPLwt and HPLdel respectively.The enzyme stability was then studied. Conservations tests using 10 % glycerol (v/v) allows the maintenance of the entire activity of HPLwt and HPLdel during five weeks of storage at -80°C. Furthermore, the addition of chemical compounds such as KCl, NaCl, Na2SO4, glycine, and glycerol can increase the efficiency of both enzymes and improve the synthesis of hexanal and 3Z-hexenal by decreasing the amount of enzyme required to produce them
Fradette, Sylvie. "Membranes bioactives robustes, étude du rôle de la structure sur les propriétés mécaniques et biocatalytiques des membranes polymères fabriquées par la méthode d'inversion de phase et contenant des biocatalyseurs microbiens". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0003/NQ39350.pdf.
Texto completo da fonteCapítulos de livros sobre o assunto "Biocatalytique"
CHEVALOT, Isabelle, e Catherine HUMEAU. "Voies d’amélioration des procédés enzymatiques". In Mise en oeuvre des procédés enzymatiques et des bactéries lactiques dans les industries agro-alimentaires, 67–115. ISTE Group, 2023. http://dx.doi.org/10.51926/iste.9137.ch5.
Texto completo da fonte