Dissertations / Theses on the topic 'Monooxygenase oxidation'
To see the other types of publications on this topic, follow the link: Monooxygenase oxidation.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 29 dissertations / theses for your research on the topic 'Monooxygenase oxidation.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Sowden, Rebecca. "The oxidation of terpenoid hydrocarbons by monooxygenase enzymes." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288518.
Full text
2
Charlton, Susan. "The particulate form of the enzyme methane monooxygenase." Thesis, University of Warwick, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323371.
Full text
3
Maurer, Steffen Christian. "Oxidationsreaktionen mittels der Cytochrom P450-Monooxygenase CYP102A1 in Enzymreaktoren." [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-28118.
Full text
4
Hogan, Matthew Charles. "Process issues in redox biocatalysis : cyclohexanone monooxygenase catalysed chiral lactone syntheses." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325655.
Full text
5
Pilkington, Simon John. "The soluble methane monooxygenase and ammonia oxidation in the obligate methanotroph 'Methylosinus trichosporium (OB3b)'." Thesis, University of Warwick, 1986. http://wrap.warwick.ac.uk/66751/.
Full textAbstract:
The aim of this project was to isolate and characterise the soluble methane monooxygenase (MMO) from the obligate methanotroph Methylosinus trichosporium (OB3b) and to investigate its role in the oxidation of ammonia. The nature and location of the MMO was shown to be dependent on the availability of copper to the organism. Cells grown in chemostat culture with copper in excess produced a particulate MMO. whereas under conditions of copper stress a soluble MMO is ,produced. This response was independent of the carbon and energy source used for growth (methane or methanol). The soluble MMO was separated into two fractions by DEAE ion exchange chromatography. Each had no MMO activity when assayed individually but had MMO activity when assayed in combination. Fraction A consisted of material that failed to bind to DEAE cellulose and from it component A of the soluble MMOwas purified. Component A had an Mr of 230000 and consisted of three subunits a, B and Y of Mr 54000. 40000 and 18500 respectively. suggesting a a2B2Y2 subunit structure. Component A could replace component A of the soluble MMO of Methylococcus capsulatus (Bath) in assays of pure components of the soluble MMO from this organism and was therefore identified as the hydroxylase component of the enzyme. Fraction C consisted Of material eluted from DEAE cellulose by 0.3 M NaC1, from it component C of the soluble MMO was partially purified. Component C was purified to a point where it consisted predominantly of two proteins of Mr 38000 and 58000. Component C could replace component C of the soluble MMO of Methylococcus capsulatus (Bath) in MMO assays of pure components of the soluble MMO from this organism and was therefore identified as the NADH:acceptor reductase component of the enzyme. The presence of a third component (component B) of the soluble MMO essential for MMO activity was demonstrated. Component B was not purified or isolated from components A or C but it was 'shown to be analogous to component B of the soluble MMO of MethYlococcus capsulatus (Bath). The close functional and physicochemical similarity between the components of the soluble MMOs from Methylosinus trichosporium (OB3b) and Methylococcus capsulatus (Bath) is discussed. as is the distinct difference between the soluble and particulate MMOs from Methylosinus trichosporium (OB3b). The soluble MMOwas shown to oxidise ammonia to hydroxylamine in that: 1. ammonia oxidation required the presence of NAD(P)H for activity as does the soluble MMO; 2. ammonia oxidation was inhibited by acetylene and 8-hydroxyquinoline. specific inhibitors of the soluble MMO. 3. Ammonia oxidation required the presence of both DEAE fractions of the soluble MMO for activity. and U. ammonia oxidation activity was always associated with the soluble MMO and was never present in extracts lacking soluble MMO activity. Hydroxylamine inhibits the soluble MMO (50% at 1,mM) and this was identified as a cause of the cessation of maximum ammonia oxidising activity after 1 minute 1n vitro. Only low levels of hydroxylamine oxidoreductase activity were measured in vitro (> 1 nmol/min/mg) and activity failed to be stimulated by the addition of a number of electron donors.
6
Keppler, Artur Franz. "Biotransformações de cetonas aromáticas e cíclicas promovidas por fungos." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/46/46135/tde-13032007-123741/.
Full textAbstract:
Nesse trabalho avaliamos o potencial enzimático de diferentes linhagens de fungos, visando determinar a presença de mono-oxigenases capazes de oxidar cetonas aromáticas e cíclicas. Todas as linhagens empregadas apresentaram atividade de álcool desidrogenase e Baeyer-Villiger mono-oxigenases. Adicionalmente foram sintetizadas oito moléculas bi-funcionalizadas com grupos sulfeto, seleneto e carbonila (cetona). Os produtos das reações biocatalisadas foram isolados e caracterizados.In this work, we evaluated the enzymatic potential of different Aspergillus strains, through the biotransformations of two substrates: 2- and 4-methylcyclohexanone (1a e 1b). All the strains employed showed alcohol dehydrogenase and Baeyer-Villiger monooxygenase (CPMO and CHMO) activities. These enzymes can perform ketone biorreduction and oxidation. Using the A. terreus SSP 1498 selected from the screening study, we prepared alcohols and lactones in good enantiosselectivity. In this way, other fungal strains were studied aiming to determine the presence of monooxygenase activity by means of the biotransformation of aromatic ketones. Like the Aspergillus, we observed that all strains used in this study showed alcohol dehydrogenase and Baeyer-Villiger monooxygenase (APMO) activities. We selected 1-phenyl-etanone and its para substituted derivates as substrates. Additionally, we synthesized eight examples of bi-functionalized compounds with sulfide, selenide and ketone groups. These compounds were submitted to the action of enzymatic system of different fungi which were selected from the initial screening. The products from the biotransformation were isolated and characterized.
7
Valentine, Ann M. (Ann Margaret) 1971. "Bioinorganic hydrocarbon oxidation : mechanistic and kinetic studies of the soluble methane monooxygenase from Methylococcus capsulates (bath)." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50508.
Full textAbstract:
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1998.Includes bibliographical references (p. 219-233).
Chapter 1. Principles of Small Molecule Activation by Metalloproteins as Exemplified by the Soluble Methane Monooxygenase -- Chapter 2. Small Molecule Binding to the Mixed-Valent Diiron Center of Methane Monooxygenase Hydroxylase from Methylococcus capsulatus (Bath) as Revealed by ENDOR Spectroscopy -- Chapter 3. An EPR Study of the Dinuclear Iron Site in the Soluble Methane Monooxygenase Reduced by One Electron at 77 K: the Effect of Component Interactions and the Binding of Small Molecules to the Dinuclear Ferric Center -- Chapter 4. An Investigation of the Reaction of Diferrous Methane Monooxygenase Hydroxylase with Dioxygen and Substrates by Rapid Freeze- Quench and Stopped-Flow Spectroscopy -- Chapter 5. Oxidation of Radical Clock Substrate Probes by the Soluble Methane Monooxygenase System -- Chapter 6. Tritiated Chiral Alkanes as Probes for the Mechanism of Hydroxylation by the Soluble Methane Monooxygenase.
by Ann M. Valentine.
Ph.D.
8
Harrison, John Samuel. "Production and characterisation of dioxygenase- and monooxygenase-catalysed oxidation products from a range of arenes and oxaarenes." Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301717.
Full text
9
Mohanty, Sujit Kumar. "A. Genetic characterization of the caffeine C-8 oxidation pathway in Pseudomonas Sp. CBB1 B. Validation of caffeine dehydrogenase as a suitable enzyme for a rapid caffeine diagnostic test." Diss., University of Iowa, 2013. https://ir.uiowa.edu/etd/4879.
Full textAbstract:
Pseudomonassp. CBB1 degraded caffeine via C-8 oxidation. Previously, a novel quinone-dependent caffeine dehydrogenase (Cdh) was shown to catalyze the oxidation of caffeine to 1,3,7-trimethyluric acid (TMU). Initial metabolite analysis using resting cells and partially purified extract of CBB1 identified transient accumulation 1,3,7-trimethyl-5-hydroxyisourate (TM-HIU), and 3,6,8-trimethylallantoin (TMA). TMA structure was confirmed; chiral analysis revealed that it was racemic. In contrast, a time-course reaction showed that one of the enantiomers of TMA accumulated nine times, and racemized in three hours. Based on this, it was proposed that TMU was converted to TM-HIU and enantiomeric TMA.
A 43-kDa NADH-dependent TMU mononxygenase (TmuM) was purified and shown to convert TMU to unstable TM-HIU. The enzyme belonged to a new family of FAD-dependent monooxygenases. The enzyme was specific for methyluric acid with no activity on uric acid. Homology model of TmuM revealed a larger, more hydrophobic active site compared to analogous uricase in the uric acid pathway.
Genes encoding heterotrimeric Cdh (cdhA,B,C) and TmuM (tmuM), were located on a 25.2-kb fragment in CBB1 genome. Gene cluster analysis relative to similar cluster in uric acid degrading organisms identified five more putative genes of the C-8 oxidation pathway, namely tmuH, tmuD, orf1, orf2, and orf3. First three genes were assigned encoding TM-HIU hydrolase (TM-HIU to TM-OHCU), TM-OHCU decarboxylase (TM-OHCU to stereospecific TMA (proposed S-(+)-TMA)), and trimethylallantoinase (stereospecific TMA to TMAA), respectively. Further, orf2 and orf3 are proposed to encode for YlbA and ArgE like hydrolase and deacetylase, which convert TMAA to glyoxylate, di- and monomethylurea. This is the first report of (a) TMA structure (b) TMU monooxygenase and TM-HIU (hydroxylation product of TMU), and (c) complete delineation of C-8 oxidation pathway by a combination of enzymology and cluster analysis.
Excessive consumption of caffeine in various forms has created a need for a rapid diagnostic test, esp. for nursing mothers and infants. Cdh was hypothesized to be suitable for this test. Sensitivity of the test was shown to be 1 ppm. A colorimetric test with partially purified Cdh and INT-dye was optimized to detect within a minute, caffeine in drugs, nursing mother's milk, and differentiate decaffeinated beverages.
10
Ray, Anirban. "Identification, Enumeration and Diversity of Nitrifying Bacteria in the Laurentian Great Lakes." Bowling Green State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1351276518.
Full text
11
dela, Seña Carlo C. "Substrate specificity and reaction mechanism of vertebrate carotenoid cleavage oxygenases." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1396444100.
Full text
12
Michel, Johannes Ehrenreich Josef. "Investigation and application of P450 monooxygenase for enantioselective oxidations /." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17076.
Full text
13
Budde, Michael. "Biokatalyse mit Cytochrom P450 Monooxygenasen: zur selektiven Oxidation von Terpenen und Fettsäuren." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-32363.
Full text
14
Vincent, Jean-Marc. "Réactivité chimique de complexes binucléaires de fer (III) à pont oxo : catalyse d'oxydation d'alcanes et agrégation d'espèces ferriques." Université Joseph Fourier (Grenoble ; 1971-2015), 1995. http://www.theses.fr/1995GRE10188.
Full textAbstract:
Le travail présente contribue à la modélisation fonctionnelle des protéines à fer-oxo. Une première étude porte sur les propriétés catalytiques en oxydation d'alcanes de nouveaux complexes bi nucléaires de fer#3#+ a pont oxo, modèles du site actif de la méthane monooxygenase (mmo). Il a été montré que les complexes bi nucléaires ferriques à pont oxo et a ligands de type bipyridine, possédaient une activité catalytique en oxydation d'alcanes importante lorsque l'oxydant utilise est l'hydroperxyde de tertiobutyle (tbuooh). Les résultats de l'étude structure/réactivité montrent que la présence d'un ligand facilement échangeable est primordiale pour l'obtention de catalyseurs performants. Une forte activité de dismutation du peroxyde d'hydrogène (h#2o#2) par les complexes bi nucléaires a été mise en évidence limitant, pour l'instant, son utilisation comme oxydant dans les réactions d'oxydation d'alcanes. L'étude des mécanismes réactionnels a permis de piéger des intermédiaires fer-peroxo. Un mécanisme impliquant à la fois des espèces radicalaires et fer-oxene est proposé. Afin d'essayer de limiter la dégradation des catalyseurs au cours des cycles catalytiques, la synthèse d'un ligand binucleant à fonction carboxylate intégrée a été réalisée. Ainsi, le premier complexe binucleaire de fer#3#+ à pont oxo dans lequel le carboxylate pontant est fourni par le ligand a été obtenu. Une deuxième étude porte sur les mécanismes d'aggregation d'espèces ferriques, phénomène implique dans la bio minéralisation du fer. Des complexes tetranucleaires et trinucleaires lineaires de fer#3#+ a ponts oxo possédant des propriétés spectroscopiques originales ont été isolés et caracterisés. En solution aqueuse, un complexe binucleaire de fer#3#+ à ligands hydroxo, modèle structural et fonctionnel des phosphatases acides pourpres (pap) a été isolé démontrant, sans ambiguïté, le caractère nucléophile d'un ligand hydroxyde du fer#3#+
15
Kranz-Finger, Sarah [Verfasser], Vlada B. [Gutachter] Urlacher, and Karl-Erich [Gutachter] Jaeger. "Oxidation pflanzlicher Triterpenoide mittels Cytochrom-P450-Monooxygenasen / Sarah Kranz-Finger ; Gutachter: Vlada B. Urlacher, Karl-Erich Jaeger." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2019. http://d-nb.info/1196870691/34.
Full text
16
Kranz-Finger, Sarah Katharina [Verfasser], Vlada B. [Gutachter] Urlacher, and Karl-Erich [Gutachter] Jaeger. "Oxidation pflanzlicher Triterpenoide mittels Cytochrom-P450-Monooxygenasen / Sarah Kranz-Finger ; Gutachter: Vlada B. Urlacher, Karl-Erich Jaeger." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2019. http://d-nb.info/1196870691/34.
Full text
17
McGhie, Emma Jane. "Studies on monooxygenases from the camphor degradation pathway in Pseudomonas putida NCIMB 10007 that are important in the catalysis of Baeyer-Villiger biotransformation reactions." Thesis, University of Exeter, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390168.
Full text
18
Rabe, Volker. "Neue Nicht-Häm-Eisenkomplexe Synthese, spektroskopische Charakterisierung und Anwendung in der katalytischen aeroben C-H-Oxidation." Berlin mbv, Mensch-und-Buch-Verl, 2009. http://d-nb.info/1000289982/04.
Full text
19
Hamze, Khalil. "Baeyer-Villiger monooxygenases d'Acinetobacter : réactions biocatalysées et dédoublements cinétiques dynamiques." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4311/document.
Full textAbstract:
L'oxydation de Baeyer-Villiger (BV) par voie enzymatique est une méthode efficace pour obtenir de lactones sous forme énantiomériquement pure. Les Baeyer-Villiger Monooxygénases (BVMO) sont ainsi capables d'oxyder de nombreux substrats avec une stéréospécificité remarquable.Nous avons recherché de nouvelles enzymes dans le génome de deux souches appartenant au genre Acinetobacter, A. baylyi ADP1 et A. baumannii AYE. Six gènes ont été clonés dans E. coli. Leur profil de substrat a été étudié en utilisant des cellules entières de ce microorganisme recombinant comme biocatalyseur. Quatre enzymes ont montré une spécificité de substrat similaire, avec une préférence pour les petites cétones cycliques et pour les substituants aryliques. Une de ces enzymes a permis le Dédoublement Cinétique Parallèle Régiodivergent d'une bicyclohepténone et la désymétrisation de cyclobutanones benzyliques avec, dans chaque cas, une énantiosélectivité intéressante car conduisant à des énantiomères rarement obtenus par réaction de BV enzymatique.Dans une seconde partie, des Dédoublements Cinétiques Dynamiques, associant réaction de BV enzymatique et racémisation in situ ont été réalisés avec des cellules entières d'E. coli produisant la Cyclohexanone Monooxygenase (CHMO) issue d'A. calcoaceticus. La racémisation de cyclohexanones α-substituées, habituellement difficilement racémisables, a été assurée par l'emploi de solutions tampons à base de sels de phosphate ou de glycine. Les -caprolactones correspondantes ont été isolées sous forme d'esters méthyliques hydroxylés quasi énantiopurs avec des rendements compris entre 70 et 80%Enzyme-mediated Baeyer-Villiger oxidation is nowadays largely recognized as an efficient method to obtain highly optically active lactones. An increasing number of Baeyer-Villiger Monooxygenases from various sources has been found to oxidize a large range of substrates with a good to excellent stereospecificity.Firstly, in order to enlarge the scope of these biotransformations, the genome of two strains of the Acinetobacter genus, A.baylyi ADP1 and A.baumannii AYE was explored. Six genes were expressed in E. coli and the substrate profile of each enzyme was studied using whole cell biotransformations. Four enzymes showed close substrate specificity with a preference for small cyclic ketones and for arylic substituents. Interestingly, one enzyme led to a Kinetic Parallel Regiodivergent Resolution of a bicycloheptenone and desymmetrisation of benzylic cyclobutanones in an enantiocomplementary manner when compared to the most of already known enzymes.The second part of this work describes the implementation of Dynamic Kinetic Resolution processes combining enzymatic BV oxidation and in situ racemization of α-substituted cyclohexanones to afford corresponding lactones in more than 50% yield. Cyclohexanone Monooxygenase (CHMO) from another Acinetobacter strain, A. calcoaceticus, was selected and the reactions were carried out with whole cells of producing CHMO E. coli strain. The racemization of α-substituted cyclohexanones, usually slowly racemized under basic conditions, was ensured by the use of containing phosphate salts or glycine buffer solutions. Several corresponding -caprolactones were isolated after methylation as enantiopure hydroxy methyl esters in 70-80% yield
20
Chabut, Barbara. "Complexes binucléaires à fer non-heminique : activité biomimétique et échange de ligands." Université Joseph Fourier (Grenoble ; 1971-2015), 1997. http://www.theses.fr/1997GRE10234.
Full textAbstract:
Notre travail s'inscrit dans le cadre de la recherche de complexes modeles de sites actifs binucleaires d'enzymes a fer non heminique et plus particulierement de l'hemerythrine et de la methane monooxygenase. Pour cela, nous avons synthetise des composes dans lesquels le centre binucleaire est dissymetrique, c'est a dire que les deux ions metalliques sont dans des environnements differents. Ainsi lors de la synthese de complexes a valence mixte, fe#i#i#ife#i#i, l'ion ferrique est dans un environnement n#3o#3 alors que l'ion ferreux se trouve dans un environnement n#2o#3x, un ligand exogene completant sa sphere de coordination. Notre projet s'articule ensuite principalement autour de deux axes : - l'etude de la structure electronique du centre a fer suivant les conditions de solvatation et d'hydratation du milieu, donc suivant la nature du ligand x. On montre par ces experiences que les proprietes spectroscopiques et electrochimiques des complexes varient suivant si x est une molecule d'acetonitrile ou une molecule d'eau et, de plus, lors de l'oxydation de la forme fe#i#i#ife#i#i-oh#2 il se produit une deprotonation spontanee pour conduire a une espece fe#i#i#ife#i#i#i-oh. - la capacite des complexes a catalyser des reactions d'hydroxylation de substrats, en presence de donneurs d'oxygene. Les resultats obtenus indiquent que les complexes possedent une activite monooxygenase et, de plus, en presence de toluene, il se produit une hydroxylation en position ortho pour donner comme produit d'oxydation l'ortho-cresol, ce qui modelise la reactivite de la toluene-2-monooxygenase. Enfin, dans une derniere partie, nous presentons la structure d'un nouveau complexe possedant une entite fe#i#i#i#2(-oh)#2.
21
Rimmel, Nina [Verfasser], Volker [Akademischer Betreuer] [Gutachter] Sieber, and Wilfried [Gutachter] Schwab. "Selektive ω-Oxidation aliphatischer Substrate – Charakterisierung von Monooxygenasen und Etablierung einer Biotransformationsplattform / Nina Rimmel ; Gutachter: Volker Sieber, Wilfried Schwab ; Betreuer: Volker Sieber." München : Universitätsbibliothek der TU München, 2016. http://d-nb.info/1120013674/34.
Full text
22
Duboc-Toia, Carole. "Réactivité chimique des complexes dinucléaires de fer (III) à pont oxo : applications en catalyse d'oxydation énantiosélective et en hydrolyse de phosphoesters." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10092.
Full textAbstract:
Modeliser le site actif d'une metalloenzyme est une approche indispensable a la caracterisation precise de son site metallique et a la comprehension de son mecanisme d'action. Au laboratoire, nous nous sommes plus particulierement interesses a deux enzymes la methane monooxygenase (mmo) et la phosphatase acide pourpre (pap) issues de la classe des proteines a fer oxo, enzymes contenant toutes au sein de leur site actif un systeme dinucleaire de fer (iii) ponte par un oxygene. Leurs activites catalytiques, oxydation d'alcanes pour la mmo et hydrolyse de phosphoesters pour la pap, ont ete reproduites a l'aide de nouveaux complexes dinucleaires de fer (iii) a pont oxo. Dans le cas de la catalyse d'oxydation d'alcanes, notre premier objectif a ete d'optimiser les premiers complexes synthetises au laboratoire. Pour se faire, la stabilite des complexes a ete amelioree et des conditions d'oxydation efficaces ont ete mises au point en utilisant le peroxyde d'hydrogene comme oxydant. Quant a leur mecanisme d'action, l'introduction d'elements de chiralite au sein des complexes a permis d'effectuer des hydroxylations enantioselectives, demontrant ainsi que la reaction est centree sur le metal. L'ensemble des resultats ainsi que la caracterisation d'un intermediaire, un complexe dinucleaire de fer (iii) -oxo -peroxo a permis de proposer un mecanisme d'action qui est proche de celui propose pour la mmo. Ces complexes optiquement actifs se sont aussi reveles etre de bons catalyseurs d'oxydation de sulfures. Ils sont chimiospecifiques puisque seul le sulfoxyde est forme et les reactions sont enantioselectives. Le mecanisme d'action a ete entierement elucide grace a des etudes cinetiques alliees a des etudes spectroscopiques. Pour la premiere fois, la reactivite d'un systeme peroxo ferrique a ete mise en evidence. Enfin, nous avons etudie les proprietes acido-basiques d'un de ces complexes dans l'eau. Ceci a conduit a la synthese du premier complexe dinucleaire de fer (iii) a pont -oxo possedant deux ligands hydroxo stables aussi bien a l'etat solide qu'en solution. Son acide conjugue s'est revele efficace en hydrolyse de phosphodiesters. L'etude du mecanisme a mis en evidence le role essentiel d'un ligand hydroxo et l'importance de la structure dinucleaire du systeme qui permet une synergie entre les deux sites metalliques. Ce systeme chimique represente le premier modele a la fois structural et fonctionnel de l'enzyme et sa reactivite valide le mecanisme d'action propose pour la pap.
23
Brondani, Patrícia Bulegon. "Investigação da seletividade de mono-oxigenases frente a substratos orgânicos de boro ou de selênio." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-03092012-142803/.
Full textAbstract:
Neste trabalho foi avaliada a seletividade (quimio ou enantiosseletividade) de quatro enzimas Baeyer-Villiger mono-oxigenases (BVMOs: PAMO, PAMO M446G, HAPMO e CHMO) frente a substratos contendo boro ou selênio. Inicialmente uma série de boro-acetofenonas foram submetidas à bio-oxidação catalisada por estas BVMOs. A enzima CHMO mostrou quimiosseletividade para transformação da ligação C-B em detrimento da reação de Baeyer-Villiger. Enquanto PAMO e PAMO M446G catalisaram a oxidação de ambas as funções em substratos 4-substituídos e a seletiva transformação de C-B no caso de substratos 3-substituídos. A enzima HAPMO levou a reação de Baeyer-Villiger e a transformação da ligação C-B em todos os casos. Quando alquenos contendo boro foram utilizados como substratos, somente aqueles que continham uma porção fenila em sua estrutura foram oxidados por BVMOs. Em nenhum dos casos foi observada reação de epoxidação e todas as enzimas levaram a transformação da ligação C-B em C-O. Compostos quirais contendo boro foram submetidos a reações com as BVMOs na tentativa de transformação enantiosseletiva. PAMO e PAMO M446G foram as melhores enzimas levando, na maioria dos casos, a satisfatória oxidação dos substratos. Entretanto, somente um composto pôde ser oxidado com boa enantiosseletividade (e.e 82-91%). Compostos quirais contendo o átomo de selênio também foram alvos de estudo com BVMOs. Novamente a enzima PAMO se mostrou a melhor opção dentre as enzimas testadas e somente quando R2 e R1 = Ph houve boa enantiosseletividade na oxidação (e.e 97 %).In this work we evaluated the selectivity (chemo or enantioselectivity) of four Baeyer-Villiger mono-oxigenases (BVMOS: PAMO, M446G PAMO, HAPMO and CHMO) in the presence of boron-containing or selenium-containing compounds. Initially, a series of boron-acetophenones were submitted to oxidation reactions mediated by BVMOs. The enzyme CHMO was chemoselective leading only to C-B bond transformation instead Baeyer-Villiger reaction. However, PAMO and PAMO M446G mediated both oxidations in 4-substituted substrates, and only the C-B transformation in 3-substituted substrates. The enzyme HAPMO leading to Baeyer- Villiger reaction and C-B transformation in all cases. When boron-containing alkenes were the substrates, only compounds with phenyl moiety in the structure were oxidized by BVMOs. It was observed only the C-B transformation and none of the epoxidation reaction. Chiral boron compounds were submitted to BVMOS mediated reactions in an attempt of enantioselective transformation. PAMO and M446G PAMO showed the best results leading, in most cases, to a satisfactory oxidation. However, only one compound was oxidized with great enantioselectivity (82-91% ee). Selenium-containing chiral compounds were also tested in reactions mediated by BVMOs. Again, PAMO showed the best results among BVMOs tested, but only when R2 e R1 = Ph the reaction occurred with great enantiosselectivity (97 % ee).
24
Bennati-Granier, Chloe. "Nouvelles enzymes fongiques pour l'amélioration de la dégradation de la biomasse lignocellulosique : étude des "Lytic Polysaccharide Monooxygenases" (LPMOs)." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4001.
Full textAbstract:
Dans le contexte actuel, il devient nécessaire de rendre les alternatives au pétrole, tel que le bioéthanol 2G, disponibles à grande échelle. Cependant, l’étape d’hydrolyse par les enzymes de Trichoderma reesei reste un verrou à un procédé économiquement stable et rentable. Ces travaux de thèse, s'intègrent dans le cadre du projet Futurol et ont pour objectifs d'identifier et de caractériser de nouvelles enzymes fongiques pour améliorer l'hydrolyse de la biomasse lignocellulosique. A partir des données protéomiques disponibles pour Podospora anserina et Fusarium verticillioides, une douzaine d'enzymes candidates ont été identifiées dans leurs sécrétomes. Ce travail de thèse s'est plus particulièrement focalisé sur les AA9s « Lytic Polysaccharide Monooxygenases » (LPMOs) de P. anserina. Parmi les LPMOs étudiées, PaLPMO9A, PaLPMO9E et PaLPMO9H, qui possèdent un CBM1, sont les plus actives sur la cellulose. La détermination de la régiosélectivité d'action a mis en évidence que PaLPMO9A et PaLPMO9H clivent la cellulose en position C1 et C4 alors que la PaLPMO9E génère uniquement des produits oxydés en C1. La PaLPMO9H est la plus versatile puisqu’elle est active sur les cello-oligosaccharides solubles et sur les polysaccharides hémicellulosiques liés en β-(1,4) (i.e., xyloglucane, glucomannane). La supplémentation du cocktail de T. reesei avec PaLPMO9E ou PaLPMO9H a permis de doubler les rendements d'hydrolyse du miscanthus prétraité. Les travaux réalisés au cours de cette thèse ont permis de démontrer l'importance de ces enzymes oxydatives dans les phénomènes de déconstruction de la lignocellulose chez les champignons filamenteuxIn the current context, it becomes essential to make alternative to oil, such as the 2G bioethanol, available at large scale. However, the hydrolysis step by Trichoderma reesei enzymes remains the major bottleneck for an economically sustainable process. The present work is part of the Futurol project, and aims at identifying and characterizing new fungal enzymes to improve the hydrolysis of lignocellulosic biomass. From the proteomic data available for Podospora anserina and Fusarium verticillioides, a dozen of interesting enzymes were identified in their secretomes. This work focuses, mainly, on the AA9s « Lytic Polysaccharide Monooxygenases » (LPMOs) from P. anserina. Among all the LPMOs studied, PaLPMO9A, PaLPMO9E and PaLPMO9H that harbored a CBM1 were the most active on cellulose. Investigation of their regioselective mode of action revealed that PaLPMO9A and PaLPMO9H oxidatively cleaved at both C1 and C4 positions while PaLPMO9E released only C1-oxidized products. PaLPMO9H that was the most versatile in terms of substrate specificity as it also displayed activity on cello-oligosaccharides and β-(1,4)-linked hemicellulose polysaccharides (e.g., xyloglucan, glucomannan). The hydrolysis yield of the pretreated miscanthus was significantly improved up to 2 fold, when the PaLPMO9E, or PaLPMO9H were supplemented to the T. reesei cocktail. This work demonstrated the importance of these oxidative enzymes for lignocellulose deconstruction by fungi. These biocatalysts open new prospects to improve the enzymatic conversion of plant biomass for 2G bioethanol production
25
Ahirwar, Saurabh Kumar. "Exploring the monooxygenase activity and selectivity of two related Cytochrome P450 enzymes." Thesis, 2020. http://hdl.handle.net/2440/127956.
Full textAbstract:
The cytochrome P450 enzymes CYP101B1 and CYP101C1 from Novosphingobium aromaticivorans DSM12444 are homologues of the CYP101D1 and CYP101D2 enzymes from the same bacterium and CYP101A1 (P450cam) from Pseudomonas putida. Both enzymes can efficiently hydroxylate norisoprenoids and related substrates in combination with the same ferredoxin reductase, ArR and a [2Fe-2S] ferredoxin, Arx, electron transfer partners. Even though the physiological substrates for both the enzymes are yet to be confirmed, the crystal structure of CYP101C1 bound to β -ionone and modelled structure of CYP101B1 has been generated. The Met82 residue of CYP101C1 aligns with the His85 residue of CYP101B1. In the crystallographic structure, this Met82 residue of CYP101C1, interacts with the carbonyl group of β -ionone, which makes it an interesting site for mutation as these could potentially alter the activity and hydroxylation of norisoprenoid substrates. CYP101B1 oxidised ẞ -ionone with the highest product formation rate (1010 ± 60 min-1). The CYP101C1 enzyme oxidised β -ionol with the highest product formation rate (1130 ± 30 min-1), whereas, the M82L-CYP101C1 mutant enzyme had the highest product formation rate (790 ± 22 min-1) with α-ionone. The selectivity for hydroxylation of norisoprenoids varies between CYP101B1 and CYP101C1. The M82L mutation however, did not change the selectivity for CYP101C1. For example, both β -damascone and β -ionone were hydroxylated at the C4 position by CYP101C1 and the M82L-CYP101C1 mutant. The CYP101B1 enzyme displayed an altered selectivity and hydroxylated these substrates predominantly at C3 position. When the substrate functional group was changed from a carbonyl to an alcohol (i.e. β-ionol), the hydroxylation occurred preferentially at the C3 position with all three enzymes. By comparing the oxidation of α -, β - and δ - substituted damascones, we found that the alkene moiety present inside the cyclohexyl ring did have an effect on the selectivity of oxidation. The β - substituted substrates are oxidised only at the C3 position by all three enzymes. The β - substituted substrates are oxidised at C3 position by CYP101B1 and at C4 position by CYP101C1 and M82L-CYP101C1. The δ - substituted substrate generates the 3,4-epoxide as the major product. To further explore the substrate range of CYP101B1 and CYP101C1, various substrates including cyclic ketones and cyclic esters were assessed to see if they induce enzyme activity and binding to the enzyme. The combinations of the best enzyme / substrates were then chosen to generate the oxidation metabolites in a larger quantity using whole-cell oxidation system to enable characterisation. The oxidation of 1-decalone by CYP101B1 generated a single major metabolite along with two minor products. The major product was characterized as 6-hydroxy-1-decalone and the minor product as 7-hydroxy-1-decalone. Comparison of the 1-decalone substrate to damascones, highlight the relationship of the oxidation metabolites 6-hydroxy-1-decalone to 4-hydroxy- β -damascone and 7-hydroxy-1-decalone to 3-hydroxy- β -damascone. Oxacyclotridecan-2-one is oxidised by CYP101B1 on a carbon opposite to the carbonyl group. Along with these, muscone and cyclopentadecanone show a dissociation constant similar to β -ionone with CYP101B1. However, the spin-state shift and activity induced by both of these substrates to CYP101B1 are comparatively smaller than ẞ -ionone. p-Tolyl acetate induced a large type-I spin-state shift and a weak binding to CYP101B1. It was oxidised at the benzylic methyl group, generating 7-hydroxy-p-tolyl acetate. Similarly, dihydroactinidiolide was also oxidised at the carbon opposite to the ester group generating 6-hydroxy-dihydroactinidiolide. However, this substrate induces a very small spin-state shift and was oxidised with low activity by CYP101B1. None of the tested substrate showed a spin-state shift larger than 10% HS or increased activity with CYP101C1.Thesis (MPhil) -- University of Adelaide, School of Physical Sciences, 2020
26
YU-CHIAOCHENG and 鄭宇喬. "Regio-Selective Oxidation of Alkyl Benzene Catalyzed by Recombinant Xylene Monooxygenase from Pseudomonas putida mt-2." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/76113619105529973307.
Full textAbstract:
碩士國立成功大學
化學系
104
Catalytic oxidation of toluene derivatives exhibits application for fine chemical supply in chemical industry. The corresponding transformation is essential to the remediation of environmental pollutants. XylMA system encoded by TOL plasmid for the protein expression of xylene monooxygenase (XylM) and its reductase (XylA) from Pseudomonas putida mt-2 was selected for an in-depth study. E. coli was employed as a host for their heterogeneously expression and purification. The catalytic conversions of alkyl benzenes were not only carried out by the whole cell catalysis mediated by the co-transformation of XylMA in E. coli system. To simplify the catalytic reaction without imposing expensive cofactor protein(s) or coenzymes, i.e. NAD(P)H, we herein also developed a facile electrochemical transformation system to conduct the direct electron transfer (DET) either directly to the intracytoplasmic membranes enriched with recombinant XylM or mediated by the iron-sulfur cofactor proteins such as XylA towards XylM protein. The X-ray absorption spectroscopy (XAS) studies of purified XylM was performed and displayed the core structure of active center in XylM protein is non-heme diiron center. Similar to recent discovery of the crystal structure of a mammalian stearoyl-CoA desaturase (Mouse SCD1), His-box (8-histidine motif) is essential for the coordination of the iron core complexes. Keywords: Xylene monooxygenase (XylM); XANES, EXAFS; Electrocatalysis
27
范錠明. "New inroads into the catalytic site and the mechanism of methane oxidation in the particulate methane monooxygenase (pMMO) from Methylococcus capsulatus (Bath) by novel mass spectrometry." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/61049342291856038878.
Full text
28
Budde, Michael [Verfasser]. "Biokatalyse mit Cytochrom-P450-Monooxygenasen : zur selektiven Oxidation von Terpenen und Fettsäuren / vorgelegt von Michael Budde." 2007. http://d-nb.info/985833173/34.
Full text
29
Yang, Chung-Ling, and 楊宗霖. "Controlled oxidation of aliphatic C-H bonds in metallo-monooxygenases: Mechanistic insights derived from studies on deuterated and fluorinated hydrocarbons by Cytochrome P450 BM3." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/t2uwv5.
Full textAbstract:
博士國立臺灣科技大學
應用科技研究所
103
The control oxidation of aliphatic C-H bonds in regio- and/or stereo-selective manner by metalloenzymes is of great interest to scientists. Cytochrome P450 BM3 from Bacillus megaterium oxidizes C12-C20 fatty acids at the ω-1, ω-2, or ω-3 position of the C?{H bond, respectively. We employ the molecular manipulation techniques to overexpress the recombinant BM3 strain and carry out its site-directed mutagenesis study for generation of a variety of strains towards variable selective oxidation with different substrates. In my study, strain 3mt, A74G F87V L188Q is exploited for the controlled oxidations of medium-chain length alkanes. Single mutation variant, BM3 mutant Ala328Phe (F328), was found with its capability of selective oxidation at the ω?{1 position of C4-C10 straight-chain alkanes. Interestingly, long-chain fatty acids (C12-C20) are no longer its substrates. It provides a great base to allow us engineering P450 BM3 protein from normal alkanes with medium-chain length such as n-octane gradually to smaller alkane such as n-butane for subsequent studies of controlled oxidation. The introduction of the second mutation, at Leu188Pro (P450 BM3-FP188) can improve the catalytic efficiency from butane to 2-butanol for 12.5%. In addtion, introducinge Ala74Glu (P450 BM3-FPE74) can shrink the substrate pocket down to half of the volume and significantly enhance the catalytic activity of butane to 2- butanol for nearly 40%. Typically, enzymes invoke host–guest chemistry to sequester the substrates within the protein pockets, exploiting sizes, shapes and specific interactions such as hydrogen-bonding, electrostatic forces and/or van der Waals interactions to control the substrate specificity, regio-specificity and stereo-selectivity. To further investigate this issue, we also develope a series of deuterated and fluorinated aliphatic substrates as probes to gain insights into the controlled C-H oxidations of hydrocarbons facilitated by these enzymes. The effects resulting from the introduction of deuterated butane (isotopomers) and fluorinated octane (Bioisostere) substituents on the mechanistic insights for C-H oxidation and the controls for regio-specificity and stereo-selectivity of the C-H bond activation are discussed.