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1
Dufernez, Fabienne. "Les superoxyde dismutases des protistes : caractérisation et origine phylogénétique". Lille 2, 2005. http://www.theses.fr/2005LIL2S030.
Testo completoAbstract (sommario):
Les organismes aérobies ont développé des mécanismes pour se protéger des attaques des espèces activées de l'oxygène produites lors du métabolisme cellulaire. La superoxyde dismutase (SOD) est une métalloenzyme du système de défense anti-oxydant. Elle catalyse la dismutation de l'anion superoxyde en peroxyde d'hydrogène. Les SOD se divisent en 2 grandes familles qui diffèrent fondamentalement d'un point de vue structural : les SOD qui utilisent simultanément le cuivre et le zinc comme métaux cofacteurs (Cu/Zn-SOD) et les SOD utilisant soit le fer (FeSOD) soit le manganèse (MnSOD) comme métal cofacteur. Sur la base d'un alignement de 261 séquences de SOD et de 12 structures cristallographiques de SOD à fer et à manganèse, nous avons analysé les conservations en terme de structure et de séquence parmi les SOD à fer et à manganèse. Les résidus caractéristiques de la fonction enzymatique, de la conformation en dimère ou tétramère et de la spécificité de métal ont été identifiés. Toutes ces données nous ont été utiles lors de nos études de SOD de nombreux protozoaires. Les protozoaires parasites étudiés jusqu'à présent ont ,en effet, la particularité de ne contenir qu'un seul type de SOD, des FeSOD qui différent des Cu/Zn SOD et SOD tétramérique à manganèse présentes chez l'humain. Ceci fait de la SOD à fer des protistes une cible thérapeutique potentielle. Chez Trypanosoma brucei, agent de la maladie du sommeil, nous avons identifié 4 gènes de SOD après interrogation des banques de données du programme de séquençage : soda, sodb1 et sodb2 ainsi que sodc nouvellement identifié. Ces 4 gènes correspondaient à des SOD dimériques à fer. Les protéines recombinantes correspondantes ont été produites et se sont révélées actives. Des modélisations structurales ont été réalisées par homologie avec des structures cristallographiques connues et ont montrées une grande similarité de structure entre ces FeSOD. Afin de déterminer la localisation cellulaire, nous avons réalisé des expériences de fusion de chacune de ces enzymes avec la GFP, ces constructions ont été transfectées dans des cellules procycliques de trypanosome. Nous avons alors mis en évidence la localisation mitochondriale des 2 enzymes FeSODA et FeSODC et la présence des FeSODB dans le cytoplasme et les glycosomes, localisation confirmée par un marquage sur fractions cellulaires : la FeSODB1 étant plutôt cytosolique et la FeSODB2 plutôt glycosomale. Chez le dinoflagellé Crypthecodinium cohnii nous n'avons retrouvé que des activités SOD correspondantes à des SOD à fer. Une famille multigénique codant pour des FeSOD a été caractérisée. La protéine recombinante correspondante à un gène complet de FeSOD dimérique a été produite et s'est révelée active. Les SOD d'un second prostiste parasite Trichomonas vaginalis ont également été étudiées. T. Vaginalis est responsable de la trichomoniase humaine, la maladie sexuellement transmissible la plus répandue à travers le monde. La recherche dans les bases de données du programme de séquençage du parasite nous a permis d'identifier 7 gènes de SOD chez ce parasite. Ces SOD comportent toutes les caractéristiques des SOD à fer dimériques et sont actives lorsqu'on les produit sous forme de protéines recombinantes. La protéine recombinante SOD6 de T. Vaginalis a été également purifiée et la structure cristallographique obtenue. Ces données sont essentielles pour la conception éventuelle d'inhibiteurs. Toutes ces séquences de FeSOD ont été incluses dans une large analyse phylogénétique afin de proposer une origine pour les FeSOD des protistes. Cette analyse confirme l'origine bactérienne de ces enzymes via des transferts de gènes de bactéries vers les protistes, suivi de duplications successives.
2
Kolahi-Ahari, Ali. "A study of superoxide dismutase activity and superoxide production in kiwifruit". Thesis, University of Canterbury. Biological Sciences, 2006. http://hdl.handle.net/10092/1343.
Testo completoAbstract (sommario):
The activity of superoxide dismutase (SOD) was determined in three kiwifruit (Actinidia) species including A. deliciosa, A. chinensis, and A. arguta. Among the species tested, the highest SOD activity was found in crude extracts prepared from fruit tissues of A. deliciosa. The highest enzyme activity was localized in seed, followed by locules, core and outer pericarp (OP). SOD activity in crude extract of whole fruit remained stable for at least one month when stored at -20℃. The effect of synthetic protease inhibitors (PI) on SOD activity was investigated. Supplementing crude kiwifruit extracts with PI improved SOD activity in freshly prepared extracts, and in extracts stored at 4℃, but had no effect on those stored at -20℃. Among the PI used, iodoacetamide (an inhibitor of cysteine proteases, for example, actinidin which is a principal protease found in kiwifruit) and PMSF (an inhibitor of serine proteases), had the most and least influence on SOD activity in crude kiwifruit extracts, respectively. There was a significant increase in SOD activity in kiwifruit (that were relatively firm) when the fruits were stored at low temperature (4℃). An increase in SOD activity was also correlated with a decrease in fruit firmness. Staining fruit tissues with nitroblue tetrazolium (NBT) provided evidence for stress-induced superoxide generation in kiwifruit tissues. Taken together, the changes in SOD activity and the capacity for stress-inducible superoxide production in post-harvest kiwifruit suggest that SOD might play a fundamental role in the storage life/ripening of kiwifruit.
3
Flamm, Hubert [Verfasser], e Gerald A. [Akademischer Betreuer] Urban. "Electrochemical microsensors for superoxide monitoring in cell culture = Elektrochemische Mikrosensoren fuer Superoxid-Monitoring in Zellkultur". Freiburg : Universität, 2014. http://d-nb.info/1123482217/34.
Testo completo
4
Kitagawa, Terutaka Terence. "Biomimetic modeling of superoxide reductase /". Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/11558.
Testo completo
5
Gibson, N. "Towards a spintrap for superoxide". Thesis, University of Aberdeen, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.592486.
Testo completoAbstract (sommario):
Several approaches to the synthesis of 1-pyrroline 1-oxides bearing an ester or alkyl halide substituent at 3-C were investigated. These compounds were sought as potentially useful spintraps for the superoxide radical anion. 5,5-Dimethyl-l-pyrroline 1-oxide (DMPO), 3,5,5-trimethyl-l-pyiroline 1-oxide (MesPPO), 2,5,5-trimethyl-l-pyrroline 1-oxide (TMPO), 4-phenyl-5,5-dimethyl-l-pyrroline 1-oxide, 2-phenyl-5,5-dimethyl-l-pyrroline 1-oxide and 2,3,5,5-Tetramethyl-3-Hydroxy-l-pyrToline 1-oxide were prepared by standard procedures. 3-Phenyl-5,5-Dimethyl-l-pyrroline 1-oxide (DMPPO) was isomerised to 3-Phenyl-3-Hydroxy-5f5-Dimethyl-1-pyrroline upon treatment with aqueous acid. This process was investigated by 1H nmr spectroscopy. DMPPO was rapidly destroyed by aqueous base and was isomerised to 3-phenyl-5,5-dimethyl-2-pyrrolidinone upon treatment with non-aqueous base. The alkylation and acylation of the enamines of 4-methyl-4-nitropentanal and 2,4-dimethyl-4-nitropentanal was slow in the absence of a Lewis acid catalyst. However the corresponding 2-dimethoxymethylaldehydes were obtained from the enamines upon treatment with stannic chloride and trimethylorthoformate and were selectively reduced to the corresponding 2-dimethoxymethyl-4-hydroxylaminopentan-l-ols. The acid-catalysed de-protection of these formyl acetals did not result in the formation of the expected 3-hydroxymethyl-1-pyrroline 1-oxides. DMPO and DMPPO reacted as an oxygen nucleophile when treated with ethyl chloroformate and acid halides in the presence of either sodium hydride or lithium diisopropylamide and gave 3-acyloxy-l-pyrrolines as products. No 3-keto-l-pyrroline 1-oxides, formed from reaction at 3-C, were isolated although some evidence of their formation in small yield was obtained from esr spectroscopy. No benzylation was observed when either DMPO or DMPPO was treated with benzyl bromide and LDA. Benzoyla-tion of MesPPO gave 3-benzoyloxy-5f5-dimethyl-l-pyrroline. Benzoylation of 4-phenyl-5,5-dimethyl-1-pyrroline 1-oxide gave 2-benzoyloxy-4-phenyl-5,5-dimethyl-pyrrolidine. Benzoylation of 2,3,5,5-Tetramethyl-3-Hydroxy-l-pyrroluie 1-oxide resulted in the dimeric tricyclic acyloxyamine 5,6,8,8^',5 -heptamethyl-3'-hydroxy-6, 1 '-dibenzoyloxy-2-oxa-1 -azabicyclo[3.1.0]octane-3 -spiro-2' -py rrolidine. The peroxyacid oxidation of 3-acyloxy-l-pyrrolines bearing one substituent at 3-C gave the corresponding oxaziridines in good yield and in enantiomeric excesses between 62 and 100%. Increasing the size of a co substituent at 3-C resulted in a corresponding decrease in the selectivity of the oxidation. The oxaziridines were unexpectedly resistant to rearrangement in ethanolic hydrogen chloride. 2,2-Dimethyl-4-benzoyloxy-6-oxa-l-azabicyclo[3.1.0]hexane isomerised to 3-benzoyloxy-5,5-dimethyl-2-pyrrolidinone when heated at reflux in xylene.
6
Olofsson, Eva. "Superoxide dismutase 1 and cataract". Doctoral thesis, Umeå : Umeå universitet, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-21032.
Testo completo
7
Sinaceur, Jamal Eddine. "Importance des dérivés réduits de l'oxygène dans l'intoxication alcoolique chez le rat : rôle de la desferrioxamine /". Paris : la Documentation française, 1987. http://catalogue.bnf.fr/ark:/12148/cb34926442c.
Testo completo
8
Vinatier, Virginie. "Exploration de la voie péroxynitrite : nouveaux donneurs de NO, étude des superoxyde dimutases à fer et application à la conception d’inhibiteurs". Toulouse 3, 2007. http://www.theses.fr/2007TOU30008.
Testo completoAbstract (sommario):
Ce travail aborde divers aspects de la chimie du peroxynitrite et de ses précurseurs , le superoxyde et le monoxyde d’azote. Plusieurs donneurs de NO dérivés du SIN-1 ont été synthétisés et étudiés dans le but de diminuer la quantité de péroxynitrite formé pendant la décomposition et d’augmenter la biodisponibilité du NO. Les superoxyde dismutases à fer, enzymes protégeant les protozoaires du stress oxydant, des parasites Plasmodium falciparum, Trypanosoma cruzi et Trypanosoma brucei ont été surexprimées et caractérisées afin de découvrir de nouveaux composés antiparasitaires. La structure de ces enzymes partiellement inactivées par la nitration du résidu tyrosine 34 a été étudiée et modélisée tandis que plusieurs stratégies ont été utilisées pour la conception d’inhibiteurs. Les modes de liaison de ces composés ont été étudiés par amarrage moléculairePeroxynitrite is the product of the very fast reaction between nitrogen oxide and superoxide. This work tackles several sides of the chemistry of these compounds. Several SIN-1 derivatives with NO releasing properties were synthesised and studied to reduce peroxynitrite production and thus increase the NO availability. Iron Superoxide Dismutases (SOD) are enzymes that protect protozoans from the oxidative stress. Enzymes from parasites Plasmodium falciparum, Trypanosoma cruzi and Trypanosoma brucei were overexpressed and characterised in order to find some new compounds with antiparasitic activity. Iron SODs are partially inactivated by nitration of the residue tyrosine 34 by peroxynitrite. The structure of the nitrated enzyme was studied and modelised. Several methods of “de novo” conception of inhibitors are descried and the binding modes of these compounds were studied by docking experiments
9
Parker, Michael William. "Structural studies on manganese superoxide dismutase". Thesis, University of Oxford, 1985. https://ora.ox.ac.uk/objects/uuid:b8fff51f-1e2f-41b1-baff-4e95b499f0de.
Testo completoAbstract (sommario):
Superoxide dismutases are widely distributed enzymes which catalyse the dismutation of superoxide radicals to dioxygen and hydrogen peroxide and are considered to be an important agent of an organism's defence against oxygen toxicity. The crystallization and low resolution structure determination of manganese superoxide dismutase (E.G. 1.15.1.1) from Bacillus stearothermophiluB is described. The enzyme crystallized in space group P21212 with two monomers per asymmetric unit and cell dimensions of ̲a=72.2Ã
, ̲b=111.1Ã
and ̲c=51.1Ã
. The crystals diffracted to beyond 2Ã
resolution but were fragile and prone to cell dimension changes. The cell dimension variability was overcome to some extent by crossllnking with glutaraldehyde. An electron density map was calculated to 6Ã
resolution initially by the method of multiple isomorphous replacement using data obtained from six heavy atom derivatives. The final map was calculated from single isomorphous replacement data using a map modification procedure. The fitting of an alpha carbon model of iron superoxide dismutase into the map suggested the iron and manganese enzymes are structurally related. The position of the metal atoms in the model solved difference Patterson maps calculated from data collected from a manganese-free crystal and from anomalous dispersion data. The latter data were collected using synchrotron radiation tuned close to the manganese absorption edge. The low resolution map and the availability of 2.4Ã
resolution native data paves the way for higher resolution X-ray studies of the crystals. A detailed analysis of amino acid sequences has been carried out on the various metal-containing superoxide dismutases. The results indicate that the enzymes can be classified according to their metal cofactor. The distribution and homology of the enzyme classes supports the endosymbiotic theory of the origin of cell organelles. The presence of the copper/zinc enzyme in Photobacterium leiognathi is shown to support the case for a eukaryote to prokaryote gene transfer.
10
Lewis, Elizabeth A. "Functional models of manganese superoxide dismutases". Thesis, University of York, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247034.
Testo completo
11
Barkley, Katherine Byer. "Characterization of superoxide dismutase from Actinomyces". Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/53905.
Testo completoAbstract (sommario):
The anaerobes Actinomyces naeslundii, A. odontolyticus and Actinomyces strain ii E1S.25D produce a Mn-containing superoxide dismutase (MnSOD). Actinomyces, once classified as yeast based on their morphology, are saprophytic organisms found among the normal flora of the mouth but can act as endogenous pathogens resulting in gingivitis and actinomycosis. The ability of Actinomyces to scavenge superoxide may increase survival of the cell from the O₂⁻-dependent killing by polymorphonuclear leukocytes and also enable the organism to be transported through an oxygenated environment from one site to another. The MnSODs were purified 85-240 fold from crude extracts with 30-60% yield by two chemical fractionations and three chromatography steps. The enzymes, Mr 96,000, were tetramers of equally sized, noncovalently associated subunits similar to the MnSOD found in Saccharomyces cerevisiae. Each of the Actinomyces MnSODs contained 0.5 g-atoms Mn/subunit and were stable in the presence of 1 mM NaCN, 1 mM NaN₃ and 2.5 mM H₂O₂. The MnSODs from Actinomyces have isoelectric points of 4.2-4.6 and are negatively charged at physiological pH. Amino acid analyses of the high molecular weight MnSODs from Actinomyces, yeast, chicken liver, and Thermus thermophilus indicated similar composition of each subunit. The second order rate constants of each Actinomyces MnSOD were measured at pH 7.8 and found to be in the range of 0.9 - 2.8 x 10⁹ M⁻¹ sec⁻¹ as compared to the rate of 1.8 x 10⁹ M⁻¹ sec⁻¹ for yeast MnSODs. Structural relatedness was evaluated by immunological studies. Rabbit antisera to each of the Actinomyces MnSODs were prepared. The MnSODs from A. naeslundii and Actinomyces strain E1S.25D both showed complete identity with their respective antibodies and partial identity with the antibody prepared against A. odontolyticus MnSOD. None of the antisera cross reacted with bovine Cu/Zn SOD, Bacteroides Fe- or MnSOD or MnSODs from either Haemophilus influenzae, Deinococcus radiodurans, or S. cerevisiae.Ph. D.
12
Kafy, Ahmed M. L. A. E. "Interactions between oligoamines and superoxide anion". Thesis, Aston University, 1987. http://publications.aston.ac.uk/12556/.
Testo completoAbstract (sommario):
1- Oligoamines and EDTA inhibited the reduction of cytochrome-C and nitrobule tetrazolium (NBT) induced by the hypoxanthine/xanthine oxidase superoxide anion generating system in the following order of effectiveness: putrescine > diaminopropane > spermidine > EDTA > spermine > cadaverine. 2- Oligoamines and EDTA did not affect the rate of urate formation from the hypoxanthine/xanthine oxidase system. 3- Oligoamines and EDTA inhibited the reduction of cytochrome-C induced by stimulated PMNL's in the same order of effectiveness as mentioned before. 4- Oligoamines and EDTA inhibited luminol dependent stimulated PMNL's chemiluminescence. 5- Oligoamines and EDTA inhibited the aerobic photoreduction of NBT. 6- Oligoamines-copper sulphate complexes inhibited the reduction of cytochrome-C induced by the hypoxanthine/xanthine oxidase system more effectively than oligoamines or copper sulphate individually. 7- Superoxide anion, hydrogen peroxide and hydroxyl radical induced breakdown of isolated intact guinea pig liver lysosomes. 8- Oligoamines and EDTA protected isolated intact guinea pig liver lysosomes from the lytic effect of superoxide anion generated either by the hypoxanthine/xanthine oxidase system or by stimulated PMNL's. 9- Oligoamines and EDTA have no stabilizing effect on isolated intact guinea pig liver lysosomes. 10- The uptake of oligoamines by lysosomes was in the following order: putrescine > spermidine > spermine. 11- Oligoamines were metabolised into aldehyde compounds either by the hypoxanthine/xanthine oxidase system or stimulated PMNL's. 12- Oligoamines and EDTA have no effect on the activities of free lysosomal enzymes (acid phosphatase and -glucosaminidase). 13- Oligoamines and EDTA inhibited lipid peroxidation in guinea pig liver lysosomes induced either by the hypoxanthine/xanthine oxidase or ascorbic acid-ferrous sulphate. 14- Oligoamines and EDTA have no effect on the release of PGE_2 from stimulated peritoneal guinea pig PMNL's. 15- Oligoamines increased the uptake of (^3H)thymidine and (^3H)leucine by stimulated peritoneal guinea pig macrophages in the following order of effectiveness: spermine > spermidine > putrescine > cadaverine. 16- PGE_2, dibutyryl Cyclic AMP, and theophylline inhibited luminol dependent stimulated peritoneal guinea pig PMNL's chemiluminescence.
13
Meissner, Felix. "Superoxide dismutase 1 regulates caspase-1". Berlin mbv, 2008. http://d-nb.info/992999286/04.
Testo completo
14
Moon, Bok Hee. "A study of the activity and characteristics of superoxide dismutase in the male reproductive parts of Petunia : a thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Plant Biotechnology in the School of Biological Sciences, University of Canterbury /". Thesis, University of Canterbury. Biological Sciences, 2006. http://hdl.handle.net/10092/1326.
Testo completoAbstract (sommario):
In the stamen (male reproductive tissue) of petunia 'Hurrah' flowers, the occurrence of SOD (superoxide dismutase) provided an effective anti-oxidative mechanism against superoxide production. Superoxide production and SOD activities at five developmental stages showed a positive correlation. The highest superoxide production and SOD activity in different parts of the stamen (anther, filament and pollen) were at stages with high metabolic activity: (i) during growing buds (in anthers and filaments) (ii) when flowers with predehiscent anthers were fully open (in pollen). In all parts of the stamen, SOD activity was the lowest at stage five (fully open flowers with dehiscent anthers), superoxide production was also lower at this stage with the exception of the pollen. The highest SOD activity was localized in anthers with the pollen, suggesting that the filaments only have a structural support function. SOD was examined on a native PAGE with regard to the isozymes present within the stamen of five developmental stages. Three isozymes, which were identified as Mn SOD, Fe SOD and Cu/Zn SOD by reactions with inhibitors, were commonly found at five developmental stages in crude extracts of anthers, filaments and pollen. The developmental stages with stronger isozyme bands on the native PAGE were consistent with the stages with higher SOD activities, and the Mn SOD and Fe SOD isozyme bands were more intense than Cu/Zn SOD bands, suggesting the activities of Mn SOD and Fe SOD in the crude extracts were much higher than Cu/Zn SOD. SOD from 1,000 stamens of dehiscent mature flowers was partially purified using ammonium sulphate fractionation and DEAE cellulose column chromatography. The purified bound fraction contained only one SOD isozyme on a native PAGE, which was shown to be a Mn SOD, as it is sensitive to neither hydrogen peroxide nor cyanide. The specific activity of the purified SOD was 66.5 U/mg and the yield of total activity was 3.0%. The progress of enzyme purification was monitored using SDS-PAGE and the bound fraction contained two major polypeptide bands. The purified enzyme activity was optimal in the range of neutral pH, but it was the highest at pH 7.8. Through incubation at various pH levels for 24 hours, favourable stability of the purified fraction was confirmed around a pH range of 7 to 8.5. The purified enzyme retained 87% of its initial activity at -20 ? after one month of storage, but at 4 ? only 38% of the initial activity remained after the same period of storage.
15
Jonsson, P. Andreas. "Superoxide dismutase 1 and amyotrophic lateral sclerosis". Doctoral thesis, Umeå : Medical Biosciences, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-611.
Testo completo
16
Berger, Christine Elizabeth Marie. "Superoxide anion in osteoclast and osteoblast function". Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265210.
Testo completo
17
Enayat, Zinat Ellaheh. "Superoxide dismutase mutations and amyotrophic lateral sclerosis". Thesis, King's College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400500.
Testo completo
18
Blackney, Michael James. "Characterising the Drosophila extracellular superoxide Dismutase gene". Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/179761/.
Testo completoAbstract (sommario):
The indiscriminate action of reactive oxygen species (ROS), if left unregulated, has long been considered contributory to a range of disease processes within the animal kingdom and is also a factor associated with ageing. Consequently modifying the molecular mechanisms that regulate ROS levels may prove therapeutic and could also positively affect longevity. One of the key components of this machinery is the superoxide dismutase (SOD) family of enzymes which regulate ROS levels by scavenging the ROS superoxide. Mammals have three distinct SOD enzymes each responsible for managing superoxide levels in different cellular compartments. In Drosophila homologues of two of the mammalian SODs, the intracellular (SOD1) and mitochondrial (SOD2) SODs, have been identified and studied extensively demonstrating a clear link between SOD and oxidative protection and survival. Recently the sequence of a third sod gene, homologous to both the relatively poorly characterised mammalian (sod3) and C. elegans (sod-4) extracellular sod, was identified in Drosophila and is also predicted to locate extracellularly (sod3). To date, no (published) work has been carried out to assess the role of sod3 within insects. This thesis reports the molecular and biochemical characteristics of sod3 in Drosophila. Detailed within are the steps taken to clone the sod3 gene which appears to be expressed as two gene products formed by alternative splicing. Furthermore, a combination of gene expression, proteomic and functional analysis of a number of sod mutants was used to: i) reveal sex specific sod gene expression; ii) validate a sod3 hypomorph mutant; iii) indicate a functional role for sod3 in protection against H2O2 induced oxidative stress; iv) suggest a SOD1-SOD3 co-dependency for maintaining Cu Zn SOD activity; v) demonstrate the appearance of genetic modifiers in the sod3 hypomorph. The findings of this report and further studies on the Drosophila sod3 gene should encourage the re-evaluation of the previous work concerning SOD’s influence on disease states and lifespan regulation.
19
Matemadombo, Fungisai. "Metallophthalocyanines as electrocatalysts and superoxide dismutase mimics". Thesis, Rhodes University, 2010. http://hdl.handle.net/10962/d1004985.
Testo completoAbstract (sommario):
Syntheses, spectral, electrochemical, and spectroelectrochemical studies of iron, cobalt, and manganese phthalocyanines are reported. The novel coordination of cobalt tetracarboxy metallophthalocyanine to an electrode premodified with aryl radicals and its use in the detection of thiocyanate are reported. This work describes the catalytic activity of cobalt phthalocyanine (CoPc) derivatives adsorbed onto glassy carbon electrodes for the electrocatalytical detection of nitrite, Lcysteine, and melatonin. The modified electrodes efficiently detected nitrite. The CoPc derivative modified electrodes proficiently detected L-cysteine whereas an un-modified electrode could not. This work presents the innovative electrochemical detection of melatonin using electrodes adsorbed with CoPc derivatives. These electrodes detected melatonin at more favorable electrochemical parameters relative to an un-modified gold electrode. The limits of melatonin detection of the modified electrodes lay in the 10⁻⁷ to 10⁻⁶ M region. The modified electrodes accurately detected capsule melatonin concentrations as specified by the supplier and could differentiate between a mixture of melatonin, tryptophan, and ascorbic acid. They reliably detected nitrite, L-cysteine, and melatonin in the 10⁻⁴ to 10⁻² M region. Metallophthalocyanine complexes substituted with thio groups were employed as self assembled monolayers (SAMs). Voltammetry, impedance, atomic force microscopy, and scanning electrochemical microscopy proved that the SAMs all act as selective and efficient barriers to ion permeability. All the SAMs in this work can be used as effective electrochemical sensors of nitrite and L-cysteine in the 10⁻⁴ to 10⁻² M region with competitive limits of detection whereas an un-modified electrode cannot detect Lcysteine. The manganese phthalocyanine SAM modified electrodes are arguably better nitrite and L-cysteine electrocatalysts relative to their iron and cobalt counterparts. Manganese phthalocyanines were used as superoxide dismutase (SOD) mimics. All manganese phthalocyanine complexes in this work acted as SOD mimics in an enzymatic system of superoxide production. From cellular studies, complexes 6d, 6e, 8d, 8e act as intracellular SOD mimics and are without significantly high cellular toxicity.
20
Pulido, Maria. "Mechanism of Superoxide Mediated Regulation of Particle Uptake and Exocytosis by a GPI-anchored Superoxide Dismutase C in Dictyostelium". FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1540.
Testo completoAbstract (sommario):
Dictyostelium discoideum is a simple model organism that can be used to study endocytic pathways such as phagocytosis and macropinocytosis because of its homology to cells of the mammalian innate immune system, namely macrophages and neutrophils. Consequently, Dictyostelium can also be used to study the process of exocytosis. In our laboratory, we generated Dictyostelium cells lacking superoxide dismutase SodC. Our data suggest that cells that lack SodC are defective in macropinocytosis and exocytosis when compared to wild type cells.
In this study I describe a regulatory mechanism of macropinocytosis by SodC via regulation of RasG, which in turn controls PI3K activation and thus macropinocytosis. Our results show that proper metabolism of superoxide is critical for efficient particle uptake, for the proper trafficking of internalized particles, and a timely exocytosis of fluid uptake in Dictyostelium cells.
21
Zetterström, Per. "Misfolded superoxide dismutase-1 in amyotrophic lateral sclerosis". Doctoral thesis, Umeå universitet, Klinisk kemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-43898.
Testo completoAbstract (sommario):
Amyotrophic lateral sclerosis (ALS) is a disease in which the motor neurons die in a progressive manner, leading to paralysis and muscle wasting. ALS is always fatal, usually through respiratory failure when the disease reaches muscles needed for breathing. Most cases are sporadic, but approximately 5–10% are familial. The first gene to be linked to familial ALS encodes the antioxidant enzyme superoxide dismutase-1 (SOD1). Today, more than 160 different mutations in SOD1 have been found in ALS patients. The mutant SOD1 proteins cause ALS by gain of a toxic property that should be common to all. Aggregates of SOD1 in motor neurons are hallmarks of ALS patients and transgenic models carrying mutant SOD1s, suggesting that misfolding, oligomerization, and aggregation of the protein may be involved in the pathogenesis. SOD1 is normally a very stable enzyme, but the structure has several components that make SOD1 sensitive to misfolding. The aim of the work in this thesis was to study misfolded SOD1 in vivo. Small amounts of soluble misfolded SOD1 were identified as a common denominator in transgenic ALS models expressing widely different forms of mutant SOD1, as well as wild-type SOD1. The highest levels of misfolded SOD1 were found in the vulnerable spinal cord. The amounts of misfolded SOD1 were similar in all the different models and showed a broad correlation with the lifespan of the different mouse strains. The misfolded SOD1 lacked the C57-C146 intrasubunit disulfide bond and the stabilizing zinc and copper ions, and was prinsipally monomeric. Forms with higher apparent molecular weights were also found, some of which might be oligomers. Misfolding-prone monomeric SOD1 appeared to be the principal source of misfolded SOD1 in the CNS. Misfolded SOD1 in the spinal cord was found to interact mainly with chaperones, with Hsc70 being the most important. Only a minor proportion of the Hsc70 was sequestered by SOD1, however, suggesting that chaperone depletion is not involved in ALS. SOD1 is normally found in the cytoplasm but can be secreted. Extracellular mutant SOD1 has been found to be toxic to motor neurons and glial cells. Misfolded SOD1 in the extracellular space could be involved in the spread of the disease between different areas of the CNS and activate glial cells known to be important in ALS. The best way to study the interstitium of the CNS is through the cerebrospinal fluid (CSF), 30% of which is derived from the interstitial fluid. Antibodies specific for misfolded SOD1 were used to probe CSF from ALS patients and controls for misfolded SOD1. We did find misfolded SOD1 in CSF, but at very low levels, and there was no difference between ALS patients and controls. This argues against there being a direct toxic effect of extracellular SOD1 in ALS pathogenesis. In conclusion, soluble misfolded SOD1 is a common denominator for transgenic ALS model mice expressing widely different mutant SOD1 proteins. The misfolded SOD1 is mainly monomeric, but also bound to chaperones, and possibly exists in oligomeric forms also. Misfolded SOD1 in the interstitium might promote spread of aggregation and activate glial cells, but it is too scarce to directly cause cytotoxicity.
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Quebec, Elizabeth Ann Hayes. "Crosslinked hemoglobin-superoxide dismutase-catalase and methemoglobin formation". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ29863.pdf.
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Regan, Elizabeth Anne. "Extracellular superoxide dismutase and oxidant stress in osteoarthritis /". Connect to full text via ProQuest. IP filtered, 2006.
Cerca il testo completoAbstract (sommario):
Thesis (Ph.D. in Clinical Science) -- University of Colorado at Denver and Health Sciences Center, 2006.Typescript. Includes bibliographical references (leaves 107-128). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;
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Wong, Kwan-yeung. "Roles of manganese superoxide dismutase in ovarian cancer". Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B39364689.
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25
Wong, Kwan-yeung, e 黃君揚. "Roles of manganese superoxide dismutase in ovarian cancer". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39364689.
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26
Temperton, Nigel James. "Functional studies on superoxide dismutase in Trypanosoma cruzi". Thesis, London School of Hygiene and Tropical Medicine (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391814.
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Coffey, Marcus Jonathan. "Human neutrophil superoxide generation and pathological oxidative stress". Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296015.
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Chen, Ying. "In vivo metal substitution in bacteroides superoxide dismutase". Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/44628.
Testo completoAbstract (sommario):
The effect of various growth conditions on the type of superoxide dismutase (SGD) formed anaerobically in three Bacteriodes species was studied. B. fragilis, B. distasonis, and B. thetaiotaomicron were grown in ironâ restricted media with or without manganese supplementation. Iron availability was decreased by treatment of the media with chelex-100, a metal-chelating resin, and addition of desferrioxamine mesylate (desferal, Ciba-Geigy), an iron chelator. Mn-containing (MnSOD) and Fe-containing superoxide dismutase (EeSOD) activities in cell extracts were differentiated by inhibition with azide and inactivation by H202. The amount of Mn-containing superoxide dismutase was estimated by the fraction of azide- and H202, -resistant activity. Cells grown in untreated media contained approximately 90% FeSOD and 10% MnSOD. Cells grown in Fe-restricted media supplemented with graded amounts of manganese synthesized a progressively larger fraction of MnSOD. Hemin, added to the Fe-restricted media, did not serve as an iron source for FeSOD formation. Superoxide dismutase specific activities varied (3-6 U/mg) in each extract but not as a function of manganese concentration.
Master of Science
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Mazura, Sergiy. "Effect of active pharmaceutical ingredients on superoxide dismutase". Thesis, Київський національний університет технологій та дизайну, 2019. https://er.knutd.edu.ua/handle/123456789/13082.
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Poinso, Alix. "Recherche d'inhibiteurs de la superoxyde dismutase à partir de substances naturelles". Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30378/document.
Testo completoAbstract (sommario):
Le but de ce travail de thèse était de rechercher de nouvelles molécules inhibitrices de la SOD dans des extraits de substances naturelles. Cette enzyme majeure du stress oxydant étant impliquée dans de nombreux mécanismes de défense des cellules cancéreuses contre l'apoptose représente une voie thérapeutique d'avenir. Nous en avons recherché dans les champignons endophytes de plantes péruviennes, ces micro-organismes produisant de nombreux métabolites de défense des plantes hôtes. Ce travail de thèse a d'abord porté sur l'isolement, la culture, l'identification, l'extraction et la caractérisation des souches de champignons endophytes. Les analyses statistiques effectuées sur ces extraits avec les résultats obtenus en HPLC ont confirmé les problèmes de variabilités qualitative et quantitative pouvant être rencontrés au cours de la culture des endophytes et décrites dans la littérature. La seconde partie expérimentale a porté sur la recherche de furocoumarines dans les extraits obtenus, en raison de leur potentiel effet inhibiteur sur la SOD. Nous avons dérépliqué ces composés dans les extraits d'endophytes au cours de deux stratégies de spectrométrie de masse réalisées en mode d'ionisation négatif. La première approche, à l'aide d'un QTOF, a abouti à l'identification de deux furocoumarines, la 5-Methyl-4H-furo[2,3-b][1]benzopyran-4-one et la déhydropachyrrhizone. La seconde, à l'aide d'un OrbiTrap, a vu l'identification de quatre autres furocoumarines : l'Ochrocarpine A, la Moellendorffiline, l'Anisolactone et l'Anhydrorutarétine .Afin de compléter cette approche métabolomique et identifier les molécules inhibitrices de la SOD, nous avons tenté de mettre au point un test d'activité de cette enzyme, rapide, peu coûteux et réalisable en routine. Nous avons sélectionné le test au pyrogallol, mais celui-ci n'a pas démontré les qualités recherchées tant au niveau de la sensibilité que de la reproductibilité. Nous orientons à présent les recherches vers des approches différentes, la recherche directe d'adduits sur la SOD par LC-MSSuperoxide dismutase is one of the major proteins controlling the oxidizing stress and cellular homeostasis. It is involved in numerous cancer cells proliferation processes. This protein is considered as major anti-cancer target for the development of new anti-cancer drugs. The goal of this work, was to research and identify an inhibitor of the SOD in endophytic fungi from Peruvian plants. These micro-organisms are known to produce numerous metabolites for host plants protection. During the preparation of endophytic extracts and their characterization by HPLC and statistical analyzes, we have pointed out a high quantitative and qualitative variability of the chemical content of endophytic extracts inside a same strain. Considering the literature we have focused our work on the identification of furocoumarins because of their potential inhibitory effect on the SOD. For this purpose two mass spectrometry strategies using negative ionization mode were carried out. With the QTOF mass spectrometer we have identified Methyl-4H-furo [2,3-b] [1] benzopyran-4-one and the déhydropachyrrhizone. With the OrbiTrap, the Ochrocarpine A, Moellendorffiline the Anisolactone and the Anhydrorutarétine were identified. Biological evaluation of the different extracts was performed using pyrogallol test. This investigation did not allow us to identify an inhibitor of the SOD. In the future we may consider seeking SOD inhibitors by looking at the formation SOD-chemical compound adducts using an LC-MS investigation
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Cheung, Suet-ting, e 張雪婷. "Effects of superoxide dismutase 1 on frontal cortical neurons". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B42924650.
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Cheung, Suet-ting. "Effects of superoxide dismutase 1 on frontal cortical neurons". Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B42924650.
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Samai, Mohamed. "Novel superoxide dismutase mimetics for protection against paraquat nephrotoxicity". Thesis, University of Brighton, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485754.
Testo completoAbstract (sommario):
Paraquat (PO), a broad-spectrum herbicide, is primarily eliminated from the body unchanged via the kidneys. Unfortunately, it is nephrotoxic; and the PO-induced nephrotoxicity involves severe renal damage caused by reactive oxygen species (ROS), specifically by increasing superoxide anion (0/-) generation in the kidney. While proven to be of benefit in animal models of organ injury involving O2.-, superoxide dismutase (SOD) and superoxide dismutase mimetics (SOOm) can suffer problems regarding their bioavailability and toxicity. Since ROS has been incriminated in the pathogenesis of several disease conditions, the search for ideal SOOm therefore continues unabated. Thus, the current study was undertaken with the overall objective of investigating and comparing the therapeutic potentials of Mn (II) and Cu (II) complexes of ethylenebis (oxyethylenenitrilo) tetraacetic acid (EGTA) and ethylenebis hydroxyphenylglycine (EHPG), novel SOOm, against PO-induced nephrotoxicity using in vitro and in vivo models. The reno-cytotoxic effects of PO on confluent NRK-52E renal cell line in the absence and presence of SOOm were assessed using biochemical assays of cellular viability and cell death. The mode of injury produced by PO in vitro was evaluated using Hoechst-Propidium iodide staining. The ability of PO to increase ROS generation, specifically O2.- and hydroxyl radicals (OW) was investigated using nitroblue tetrazolium reduction/hydroxyethidium fluorescence and deoxyribose assay respectively. ROS-mediated cell damage was assessed via determination of lipid peroxidation, inhibition of DNA and protein synthesis, DNA single strand breaks and poly- (AOP-ribose) polymerase (PARP) activation using the thiobarbituric acid reactive substance assa¥., cellular incorporation of [3H]-thymidine and [3H]-leucine, a DNA precipitation and [ H]-NAO incorporation assays respectively. In addition, the effects of PO on the renal activities and expression of SOD, catalase (CAT) and glutathione peroxidase (GSH-Px) in confluent NRK-52E renal cells in culture were also evaluated. The reno-cytotoxic effects of paraquat were mediated in part by oxidative stress injury secondary to increase generation of ROS; specifically 0/- and OW. This was accompanied by a reduction in the activity and expression of SOD, a reduction in the activity with no significant change in the expression of CAT and an increased in the activity of GSH-Px. Oxidative stress injury was further confirmed by increased lipid peroxidation, inhibition of DNA and protein synthesis, and increased DNA single strand breaks with a subsequent increased in PARP activation. The doses of paraquat examined predominantly produced necrotic cell death. EUK-134 (30-300 IJM), tempol (0.1-1.0 mM) and Mn (II) and Cu (II) complexes of EGTA (10100 IJM) and EHPG (10-100 IJM) were able to improve cellular viability and reduce PO-mediated cell death in vitro via dismutation and/or scavenging of O2.- and reduced OH· generation. Mn (II) complexes displayed greater efficacy than Cu (II) complexes and at equivalent concentrations, Mn (II)-EHPG provided greatest protection. Thus, the hypothesis that, these novel SOOm, particularly Mn (II) complexes of EHPG and EGTA, could provide similar beneficial effect in vivo was tested in rodent model of paraquat-induced nephrotoxicity. Administration of a single intraperitoneal dose of PO (10-100 mg/kg) to male wistar rats (weighing 200-250 g) produced acute renal failure (ARF) within 24-48 hours as evidenced by a significant increase in serum creatinine levels and fractional excretion of sodium (FENa) and a concomitant reduction in creatinine clearance. Unlike Mn (II)-EGTA (2 mg/kg), Mn (II)-EHPG (4 mg/kg) was able to significantly attenuate the PO-induced ARF. In contrast to SOD and/or conventional SOOm which can display pro-oxidant actions at higher concentrations these complexes were not toxic at the doses examined. Since the clinical toxicity profiles of EGTA and EHPG are already known, these novel SOOm particularly Mn (II)-EHPG could be beneficial in attenuating disease conditions involving ROS generation.
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MacKenzie, Andrew. "Protection of vascular nitric oxide by superoxide dismutase mimetics". Thesis, University of Glasgow, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266683.
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Hiran, Tejindervir Singh. "The superoxide production and NADPH oxidase of articular chondrocytes". Thesis, University of the West of England, Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264625.
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Münch, Christian. "Initiation and propagation of mutant superoxide dismutase 1 misfolding". Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609791.
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Ma, Huaibo. "Modeling the Structure and Mechanism of Nickel Superoxide Dismutase". Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1303327993.
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Durazo, Armando. "Hydrogen/deuterium exchange studies on copper-zinc superoxide dismutase". Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1495960591&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Forquer, Isaac Paul. "Superoxide production in respiratory electron transport minimization and utilization". Pullman, Wash. : Washington State University, 2008. http://www.dissertations.wsu.edu/Dissertations/Fall2008/i_forquer_12209.pdf.
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Lu, Dongning. "Nitric oxide donors and superoxide probes synthesis and properties /". Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1235668199.
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Trist, Benjamin. "Superoxide dismutase 1 in the aetiology of Parkinson’s disease". Thesis, The University of Sydney, 2019. http://hdl.handle.net/2123/20579.
Testo completoAbstract (sommario):
Parkinson’s disease is the most common neurodegenerative movement disorder worldwide, and is the fastest growing neurological disease ahead of Alzheimer’s disease. Characteristic motor dysfunction results from the selective death of dopamine neurons in the substantia nigra pars compacta, however the aetiology of this neuron loss remains unknown. As such, current treatments help to alleviate Parkinsonian motor symptoms, but none are able to slow or halt the rate of dopaminergic neuron loss. A greater understanding of the molecular pathways leading to dopamine neuron death will accelerate the development of disease-modifying treatments that slow or halt neurodegeneration in this disorder. This thesis focusses on three focal points within the parkinsonian degenerative cascade; oxidative stress, copper dyshomeostasis, and protein misfolding, and aims to introduce the antioxidant copper-binding protein, superoxide dismutase 1 (SOD1), as an important nexus between these key pathologies. I describe, for the first time, misfolding and dysfunction of SOD1 localized to degenerating brain regions in Parkinson’s disease, which is significantly associated with both Lewy proteinopathy and neuron death in these regions. Importantly, I provide evidence that the development of this pathology precedes nigral dopamine neuron loss, and is therefore likely to be a causative factor in, rather than a result of, neurodegeneration in Parkinson’s disease. The sole use of post-mortem tissues within this study ensured any identified biochemical changes accurately reflected endogenous changes occurring within PD and ALS patients; a major criticism of current model systems aiming to recapitulate PD and ALS pathology. My work proposes SOD1 may constitute a novel target for therapeutic interventions aiming to slow the rate of dopaminergic neuron loss in Parkinson’s disease. Novel SOD1 proteinopathy in the Parkinson’s disease brain bears remarkable similarities to neurotoxic SOD1 proteinopathy in a proportion of familial amyotrophic lateral sclerosis (fALS) patients, suggesting similar pathways to neuron death in both disorders. The absence of SOD1 gene mutations in Parkinson’s disease patients exhibiting substantial SOD1 proteinopathy strengthens data from SOD1-fALS research demonstrating that non-genetic factors play key roles in SOD1 misfolding and dysfunction, especially biometal dyshomeostasis and oxidative stress. I demonstrate that these factors may also underlie the misfolding of soluble wild-type SOD1 protein in the vulnerable ventral spinal cord in non-SOD1-fALS and sALS patients, and propose that SOD1 toxicity arises in these patients irrespective of the formation of large insoluble misfolded SOD1 deposits. Importantly, shared pathways to neurodegeneration in Parkinson’s disease and ALS identified within this thesis highlight the potential for the translation of therapeutic approaches targeting SOD1, already in clinical trials for ALS, into disease-modifying therapies for Parkinson’s disease.
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Wegerich, Franziska. "Engineered human cytochrome c : investigation of superoxide and protein-protein interaction and application in bioelectronic systems". Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2011/5078/.
Testo completoAbstract (sommario):
The aim of this thesis is the design, expression and purification of human cytochrome c mutants and their characterization with regard to electrochemical and structural properties as well as with respect to the reaction with the superoxide radical and the selected proteins sulfite oxidase from human and fungi bilirubin oxidase. All three interaction partners are studied here for the first time with human cyt c and with mutant forms of cyt c.
A further aim is the incorporation of the different cyt c forms in two bioelectronic systems: an electrochemical superoxide biosensor with an enhanced sensitivity and a protein multilayer assembly with and without bilirubin oxidase on electrodes.
The first part of the thesis is dedicated to the design, expression and characterization of the mutants. A focus is here the electrochemical characterization of the protein in solution and immobilized on electrodes. Further the reaction of these mutants with superoxide was investigated and the possible reaction mechanisms are discussed.
In the second part of the work an amperometric superoxide biosensor with selected human cytochrome c mutants was constructed and the performance of the sensor electrodes was studied. The human wild-type and four of the five mutant electrodes could be applied successfully for the detection of the superoxide radical.
In the third part of the thesis the reaction of horse heart cyt c, the human wild-type and seven human cyt c mutants with the two proteins sulfite oxidase and bilirubin oxidase was studied electrochemically and the influence of the mutations on the electron transfer reactions was discussed.
Finally protein multilayer electrodes with different cyt form including the mutant forms G77K and N70K which exhibit different reaction rates towards BOD were investigated and BOD together with the wild-type and engineered cyt c was embedded in the multilayer assembly. The relevant electron transfer steps and the kinetic behavior of the multilayer electrodes are investigated since the functionality of electroactive multilayer assemblies with incorporated redox proteins is often limited by the electron transfer abilities of the proteins within the multilayer. The formation via the layer-by-layer technique and the kinetic behavior of the mono and bi-protein multilayer system are studied by SPR and cyclic voltammetry.
In conclusion this thesis shows that protein engineering is a helpful instrument to study protein reactions as well as electron transfer mechanisms of complex bioelectronic systems (such as bi-protein multilayers). Furthermore, the possibility to design tailored recognition elements for the construction of biosensors with an improved performance is demonstrated.Ziel dieser Arbeit ist es genetisch veränderte Formen von humanem Cytochrom c herzustellen und diese einerseits hinsichtlich der Reaktion mit dem Sauerstoff-Radikal Superoxid aber auch mit anderen Proteinen zu untersuchen. Zusätzlich sollen die verschiedenen Protein-Mutanten in neuartige bioelektronische Systeme eingebracht werden. Es wurden insgesamt 20 Cytochrome c Mutanten designt, rekombinant exprimiert und aufgereinigt. Es konnte in dieser Arbeit gezeigt werden, dass sich die Reaktion von Cytochrom c mit dem negativ geladenen Superoxid durch gezielte Mutationen, die zusätzliche positive Ladungen in das Molekül bringen, um bis zu 30 % erhöhen lässt. Es wurde aber auch deutlich, dass andere Eigenschaften des Proteins sowie dessen Struktur durch die Mutationen geändert werden können. Cytochrom c Mutanten mit einer erhöhten Reaktionsrate mit Superoxid konnten erfolgreich in einen Superoxid-Biosensor mit erhöhter Sensitivität eingebracht werden. Weiterhin wurde einige Mutanten hinsichtlich Ihrer Interaktion mit den zwei Enzymen Sulfitoxidase und Bilirubinoxidase untersucht. Hier konnten ebenfalls unterschiedliche Reaktivitäten festgestellt werden. Schließlich wurden ausgewählte Protein-Varianten mit und ohne den zuvor untersuchten Enzymen in ein Multischicht-Elektroden-System eingebettet und dessen kinetisches Verhalten untersucht. Es wurde gefunden, dass die Schnelligkeit mit der Cytochrom c mit sich selbst Elektronen austauschen kann, eine Limitierung der Größenordnung der katalytischen Ströme darstellt. Diese Selbstaustausschrate wurde durch die eingeführten Mutationen verändert. So verdeutlicht diese Arbeit, dass „Protein-Engineering“ ein gutes Hilfsmittel sein kann, um einerseits Proteinreaktionen und komplexe Elektronentransferreaktionen in Multischichten zu untersuchen, aber auch ein potentes Werkzeug darstellt mit dem zugeschnittene Biokomponenten für Sensoren mit erhöhter Leistungsfähigkeit generiert werden können.
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Rose, Andrew Civil & Environmental Engineering Faculty of Engineering UNSW. "Availability of iron to the marine cyanobacterium Lyngbya majuscula". Awarded by:University of New South Wales. Civil and Environmental Engineering, 2005. http://handle.unsw.edu.au/1959.4/20569.
Testo completoAbstract (sommario):
Iron is an essential micronutrient that is required by some microorganisms in relatively large quantities. This is problematic for those inhabiting marine environments, where iron is highly insoluble and the dissolved fraction is predominantly strongly bound to organic compounds. Due to low supply and high demand, iron limits primary productivity in many oceanic waters, and may also limit growth of organisms in coastal waters under some circumstances. Recent incidents of explosive growth (???blooms???) of the noxious filamentous cyanobacterium Lyngbya majuscula in the coastal marine waters of Moreton Bay, Queensland, have prompted speculation that terrestrial human activities have increased iron availability to the organism, thus overcoming previous limitations on growth imposed by scarcity of the nutrient. This thesis describes work investigating the chemical form of iron in coastal waters under various environmental conditions and the way in which this influences its availability to L. majuscula. Chemical speciation of iron was investigated as a function of terrestrial-derived inputs of natural organic matter (NOM) of variable origin and sunlight in coastal marine waters, employing chemiluminescence-based and spectrophotometric techniques with high sensitivity and temporal resolution. These techniques allowed determination of iron and other chemical parameters at naturally occurring (typically nanomolar) concentrations. The mechanism of iron acquisition by L. majuscula was also investigated using a radioisotope-labelling labelling technique in addition to the other techniques described. Results indicated that iron speciation can be described by five classes: inorganic dissolved and organically complexed dissolved iron in both ferrous (reduced) and ferric (oxidised) forms, and precipitated inorganic iron. Simulation of laboratory results by numerical kinetic modelling of the processes investigated indicated that while the thermodynamic impetus is strongly towards precipitated iron, iron complexation by NOM and its reduction by sunlight-mediated processes and/or L. majuscula results in meta-stable dissolved species that are more readily available to L. majuscula. Superoxide is a critical intermediate in iron reduction by both sunlight and L. majuscula. Thus L. majuscula is capable of altering iron speciation to increase its availability, however uptake is also strongly dependent on environmental conditions and may be enhanced by increased inputs of iron, NOM and sunlight into coastal waters.
44
Tew, D. G. "Some reactions of spin traps". Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355814.
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Bendall, Jennifer Kate. "Physiology and pathophysiology of cardiac NADPH oxidase". Thesis, King's College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289766.
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Miwa, Satomi. "Mitochondrial superoxide production in Drosophila : topology, characteristics and relevance to ageing". Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616112.
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Shearer, Jason Michael. "Synthetic models for metalloenzymes containing sulfur-metal bonds /". Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8681.
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Heller, Maija Iris [Verfasser]. "Superoxide reactions in seawater : evaluating the impact of superoxide on trace metal redox cycles and dust dissolution in the open ocean / Maija Iris Heller". Kiel : Universitätsbibliothek Kiel, 2010. http://d-nb.info/1019984244/34.
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Bond, Christopher J. "Regulation, structure and folding of enzymes /". Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/9247.
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50
Bergemalm, Daniel. "Mutant superoxide dismutase-1-caused pathogenesis in amyotrophic lateral sclerosis". Doctoral thesis, Umeå : Umeå university, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-31116.
Testo completo