Dissertations / Theses on the topic 'Tyrosine oxidation'
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Kadlčík, Vojtěch. "Oxidation of beta-amyloid and model peptides." Paris 11, 2006. http://www.theses.fr/2006PA112008.
Full textThe goal of my thesis work was to characterize oxidation products of beta-amyloid peptide (Abeta), which is implied in the development of Alzheimer's disease. To study the effect of peptide structure on the redox processes, oxidation properties of Abeta(1-40) were compared to the peptide with reverse sequence, Abeta(40-1). Azide and hydroxyl radicals used for oxidation were produced by gamma radiolysis. Final products were characterized by a variety of analytical techniques (HPLC, GC, MALDI-TOF MS, fluorescence and raman spectrometry). To establish the role of peptide environment on its redox properties, oxidation was carried out in three different systems: homogeneous aqueous solution, micellar system (SDS) and in the presence of phospholipids vesicles (POPC). In homogeneous aqueous solution, oxidation products are different for both peptides. The main oxidation targets are Met35 for Abeta(1-40) and Tyr10 for Abeta(40-1). The presence of micelles and phospholipid vesicles has an important impact on the oxidation pathways. These changes could be related to changes in peptide conformations studied by circular dichroism. We have also shown that Abeta degradation products may catalytically induce alternation of phospholipids. This process is initiated by reaction of hydrogen radicals with the peptide. Our results are interesting in the context of the development of Alzheimer's disease as they may bring an insight into the role of Abeta(1-40) interaction with phospholipids membrane for the redox properties of the peptide
Wells, Geoffrey. "Chemical diversity from the oxidation of bioactive phenols." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324523.
Full textHingorani, Kastoori. "Photo-oxidation of tyrosine in a bio-engineered bacterioferritin 'reaction centre'." Phd thesis, Canberra, ACT : The Australian National University, 2012. http://hdl.handle.net/1885/11774.
Full textLaButti, Jason N. Gates Kent S. "Investigations into the chemistry of protein tyrosine phosphatase redox regulation." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6158.
Full textSong, Wei. "MASS SPECTROMETRY-BASED HIGH THROUGHPUT APPROACH FOR IDENTIFICATION OF MOLECULAR MODIFICATION OF OXIDATIVE PROCESS IN RESPIRATORY." Cleveland State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=csu1226685494.
Full textSjöholm, Johannes. "Trapping Tyrosine Z : Exploring the Relay between Photochemistry and Water Oxidation in Photosystem II." Doctoral thesis, Uppsala universitet, Molekylär biomimetik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-173575.
Full textJenson, David L. Jenson. "Proton-coupled electron transfer and tyrosine D of phototsystem II." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29667.
Full textCommittee Chair: Bridgette Barry; Committee Member: Ingeborg Schmidt-Krey; Committee Member: Jake Soper; Committee Member: Nils Kroger; Committee Member: Wendy Kelly. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Machado, Luciana E. S. F., Tun-Li Shen, Rebecca Page, and Wolfgang Peti. "The KIM-family protein-tyrosine phosphatases use distinct reversible oxidation intermediates: Intramolecular or intermolecular disulfide bond formation." AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 2017. http://hdl.handle.net/10150/624478.
Full textSalsman, Scott J. "Redox regulation of protein tyrosine phosphatases in cell membrane receptor-mediated signal transduction." Oklahoma City : [s.n.], 2005.
Find full textCooper, Ian Blake. "Photosynthetic water oxidation and proton-coupled electron transfer." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26707.
Full textCommittee Chair: Bridgette Barry; Committee Member: El-Sayed, Mostafa; Committee Member: Fahrni, Christoph; Committee Member: Kröger, Nils; Committee Member: McCarty, Nael. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Sivaramakrishnan, Santhosh Gates Kent S. "Biologically relevant chemistry of sulfur heterocycles from redox regulation of PTP1B to the biological activity of s-deoxy leinamycin." Diss., Columbia, Mo. : University of Missouri--Columbia, 2008. http://hdl.handle.net/10355/7107.
Full textKeough, James M. "Redox active tyrosines in photosystem II: role in proton coupled electron transfer reactions." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47738.
Full textKrey, Grigorios Dimitriou. "Cloning, nucleotide sequence, and expression in E. coli of the flavodoxin gene from Desulfovibrio vulgaris (Hildenborough) : investigation of the role of tyrosine-98 on the oxidation-reduction properties of the flavodoxin /." The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487676847117393.
Full textSousa, Roberta Regina Ruela de. "Estudo por oxido-redução de uma proteina tirosina fosfatase (CD45) purificada de membrana de linfocitos humanos." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314761.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-06T06:33:37Z (GMT). No. of bitstreams: 1 Sousa_RobertaReginaRuelade_M.pdf: 3257089 bytes, checksum: 29f24a432f8c0bfd7dd71af48cc7608a (MD5) Previous issue date: 2005
Resumo: As proteínas tirosina fosfatases (PTP) (EC 3.1.3.48) são enzimas regulatórias chaves que participam na transdução de sinal e são essenciais na regulação do crescimento, diferenciação, ciclos celulares, na transcrição gênica, resposta imune e outros processos. Esta classe de enzimas, que contém cisteína no sítio ativo, pode ser inativada por agentes oxidantes. Neste trabalho, estudamos os efeitos de peróxido de hidrogênio e t-butil hidroperóxido, compostos que induzem estresse oxidativo, na atividade de uma PTP purificada de membranas de linfócitos humanos, indicativamente a CD45. A PTP foi purificada de membranas de linfócitos humanos através de cromatografias de troca iônica (DEAE Sepharose) e exclusão molecular (Sephacryl S-200). A purificação enzimática foi acompanhada por SDS-PAGE e eletroforese bidimensional. A atividade enzimática foi determinada através de incubação a 37°C por 30 min em pH 5,0 em presença de 5 mM de p-nitrofenil fosfato (pNPP) como substrato. A enzima obtida da cromatografia de exclusão molecular apresentou uma massa molecular relativa de aproximadamente 200 kDa, reconheceu mais eficientemente tirosina fosfato (cerca de 3,2 vezes) como substrato quando comparado ao pNPP, e foi inibida por inibidores específicos de PTP, tais como vanadato (40%), pervanadato (100%), p-cloromercuribenzoato (20%) and Cu2+ (95%). Ácido okadáico, um inibidor específico de serina e treonina proteína fosfatases, não afetou a atividade da PTP de membranas de linfócitos. Estes resultados de caracterização sugerem fortemente que a PTP purificada de membranas de linfócitos humanos é a CD45. Peróxido de hidrogênio e t-butil hidroperóxido inibiram a atividade dessa proteína com valores de IC50 (concentração do composto que produz 50% de inibição enzimática) de 50 µM e 16 mM, respectivamente. Glutationa reduzida (GSH) protegeu parcialmente a enzima contra estes oxidantes, porém proteções totais foram obtidas quando se adicionava 250 mM de desferoxamina ao meio de ensaio. Nossos resultados sugerem que essa proteína pode ser regulada por alteração do estado de oxidação dos grupos funcionais do sítio ativo e que esta regulação poderia fornecer um mecanismo de controle celular através de espécies reativas de oxigênio
Abstract: Protein phosphatases, that dephosphorylate proteins in residues of threonine, serine and tyrosine, are a class of enzymes that can be stressed by compounds present in oxidant or reductant environments. In particular, the protein tyrosine phosphatases (PTP) (EC 3.1.3.48) are key regulatory enzymes that participate in signal transduction and are essential for regulating cellular growth, differentiation, cell cycle, gene transcription, immune response and other processes. This class of enzymes, which contain cysteine in the active site, can be inactivated by oxidant reagents. In this work we have studied the effect of hydrogen peroxide and t-butyl hydroperoxide, compounds that induce oxidative stress, on a purified PTP (CD45) from membrane human lymphocytes. PTP was purified from human lymphocyte membranes through ion exchange (DEAE Sepharose) and molecular exclusion (Sephacryl S-200) chromatographies. The enzyme purification was followed by SDS-PAGE and 2D electrophoresis. The enzyme activity was determined by incubation at 37oC for 30 minutes at pH 5.0 in presence of 5 mM p-nitrophenylphosphate (pNPP) as substrate. The enzyme obtained from molecular exclusion chromatography had a relative molecular mass of approximately 200 kDa, recognized more efficiently tyrosine phosphate (about 3.2-fold) as substrate when compared with p-NPP, and was inhibited by specific PTP inhibitors, such as, vanadate (40%), pervanadate (100%), p-chloromercuribenzoate (20%) and Cu2+ (95%). Okadaic acid, a specific serine and threonine protein phosphatases inhibitor, did not significantly affect the lymphocyte membrane PTP activity. These characterization results strongly suggest that the membrane PTP purified from human lymphocytes was the CD45. Hydrogen peroxide and t-butyl hydroperoxide inhibited the CD45 activities with IC50 (concentration of compound that produces 50% enzyme inhibition) values of 50 µM and 16 mM, respectively. Reduced glutathione (GSH) partially protected the enzyme against these oxidations, but full protections were observed when 250 mM deferoxamine were added to the assay medium. Our results suggest that CD45 can be regulated by altering the oxidation state of active site functional groups, and that this regulation could provide a mechanism of cell control by reactive oxygen species
Mestrado
Bioquimica
Mestre em Biologia Funcional e Molecular
Offenbacher, Adam R. "Protein structural changes and tyrosyl radical-mediated electron transfer reactions in ribonucleotide reductase and model compounds." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39473.
Full textRuf, Rebecca A. S. Pielak Gary J. "Tyrosine and the oxidative aggregation of alpha-synuclein." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2543.
Full textTitle from electronic title page (viewed Oct. 5, 2009). "... in partial fulfillment of the requirements for the degree of Doctorate of Philosophy in the Department of Chemistry." Discipline: Chemistry; Department/School: Chemistry.
Salehi, S., K. Abdollahi, R. Panahi, Nejat Rahmanian, M. Shakeri, and B. Mokhtarani. "Applications of Biocatalysts for Sustainable Oxidation of Phenolic Pollutants: A Review." MDPI, 2021. http://hdl.handle.net/10454/18596.
Full textPhenol and its derivatives are hazardous, teratogenic and mutagenic, and have gained significant attention in recent years due to their high toxicity even at low concentrations. Phenolic compounds appear in petroleum refinery wastewater from several sources, such as the neutralized spent caustic waste streams, the tank water drain, the desalter effluent and the production unit. Therefore, effective treatments of such wastewaters are crucial. Conventional techniques used to treat these wastewaters pose several drawbacks, such as incomplete or low efficient removal of phenols. Recently, biocatalysts have attracted much attention for the sustainable and effective removal of toxic chemicals like phenols from wastewaters. The advantages of biocatalytic processes over the conventional treatment methods are their ability to operate over a wide range of operating conditions, low consumption of oxidants, simpler process control, and no delays or shock loading effects associated with the start-up/shutdown of the plant. Among different biocatalysts, oxidoreductases (i.e., tyrosinase, laccase and horseradish peroxidase) are known as green catalysts with massive potentialities to sustainably tackle phenolic contaminants of high concerns. Such enzymes mainly catalyze the o-hydroxylation of a broad spectrum of environmentally related contaminants into their corresponding o-diphenols. This review covers the latest advancement regarding the exploitation of these enzymes for sustainable oxidation of phenolic compounds in wastewater, and suggests a way forward.
Griaud, François. "Proteomic analysis of leukaemogenic protein tyrosine kinase action." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/proteomic-analysis-of-leukaemogenic-protein-tyrosine-kinase-action(ff9d490b-5a94-45fc-a857-4f0826e4a11a).html.
Full textPetrola, Maria Juracy Solon. "Perfil do estresse oxidativo em pacientes portadores de Leucemia MielÃide CrÃnica." Universidade Federal do CearÃ, 2011. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10856.
Full textA Leucemia mielÃide crÃnica (LMC) à caracterizada pela expansÃo clonal de cÃlulas progenitoras hematopoÃticas, resultante da translocaÃÃo (9:22). O oncogene de fusÃo BCR-ABL, no cromossomo Ph, à transcrito e traduzido numa proteÃna de fusÃo BCR/ABL. A tirosina quinase (TK) ABL na proteÃna de fusÃo à constitutivamente ativada sendo necessÃria para os eventos leucemogÃnicos iniciais da LMC e sua atividade induz a produÃÃo de espÃcies reativas de oxigÃnio (EROs). De particular relevÃncia para LMC à o fato de que um aumento de EROs pode ter consequÃncias, facilitando a instabilidade genÃmica podendo contribuir para a progressÃo da doenÃa. O objetivo do estudo foi determinar o perfil oxidativo em pacientes com LMC, em acompanhamento ambulatorial no Hospital UniversitÃrio Walter CantÃdio (HUWC). Trata-se de um estudo transversal constituÃdo de 30 pacientes adultos, com diagnostico clÃnico e laboratorial de LMC, em tratamento com inibidores de (TK) de 1 e 2 geraÃÃo. As concentraÃÃes de malonaldeÃdo (MDA) e de nitrito (NO2-) foram realizadas por mÃtodo espectofotomÃtrico. As atividades das enzimas Glutationa peroxidase (GSH-Px) e catalase (CAT) foram determinadas no hemolisado, por kit Glutathione Peroxidase Cellular Activity Assay (Sigma-Aldrich) e por espectofotometria, respectivamente. Glutationa total, glutationa reduzida (GSH reduzida), glutationa oxidada (GSSG) foram determinadas por kit Total Glutathione Activity (Assay Designs, Inc) e calculada a relaÃÃo GSH/GSSG. Para a anÃlise estatÃstica de dados nÃo paramÃtricos foi utilizado o ANOVA e o teste de mÃltiplas comparaÃÃes de Tukey. Foi considerado o nÃvel mÃnimo de significÃncia de 5%. As concentraÃÃes mÃdia de MDA e de NO2- foram aumentadas nos pacientes com LMC em relaÃÃo ao controle, independente da atividade da doenÃa. O perfil antioxidante foi caracterizado pela diminuiÃÃo da CAT e aumento da GSH-Px tambÃm independente da atividade da doenÃa. A GSH reduzida se apresentou diminuÃda, a GSSH, aumentada e a relaÃÃo GSH/GSSG diminuÃda. Os pacientes em uso de inibidores de TK de 2 geraÃÃo apresentaram parÃmetros do estresse oxidativo significativamente elevados em relaÃÃo ao grupo controle. Conclui-se que os pacientes com LMC estÃo sob estresse oxidativo e com atividade antioxidante comprometida.
Bucknall, Martin Paul Medical Sciences Faculty of Medicine UNSW. "Dityrosine as a biomarker of free radical induced oxidative damage in diseases of ageing." Awarded by:University of New South Wales. School of Medical Sciences, 2006. http://handle.unsw.edu.au/1959.4/30207.
Full textHébert, Chatelain Etienne. "Impact des phosphorylations sur tyrosine sur le métabolisme mitochondrial : régulation et impacts fonctionnels des phosphorylations induites par la Src kinase." Thesis, Bordeaux 2, 2011. http://www.theses.fr/2011BOR21830/document.
Full textMitochondria are implicated in several key cellular processes. They are producing most part of the energy that is consumed by the cell via oxidative phosphorylation processes (OXPHOS). Phosphorylation of different components implicated in OXPHOS are known to constitute an important regulation pathway of energetic production. The objective of this thesis was to understand how tyrosine phosphorylation induced by the Src kinase could influence OXPHOS. First, it was shown that Src kinase mediated phosphorylation can be regulated directly in mitochondria, inducing phosphorylation of several mitochondrial proteins and different effects on OXPHOS. I also demonstrated that Src kinase is also present in mitochondria of cancer cells where it can lead to phosphorylation of NADH-oxidoreductase. This phosphorylation site is associated with increase of OXPHOS which could be implicated in the establishment of global phenotype of cancer cells
Liu, Yuting. "Chronic oxidative stress causes amplification and overexpression of ptprz1 protein tyrosine phosphatase to activate β-catenin pathway." Kyoto University, 2008. http://hdl.handle.net/2433/135838.
Full textSgaravatti, Angela Malysz. "Efeito do ácido gama-hidroxibutírico e da tirosina sobre parâmetros de estresse oxidativo em córtex cerebral de ratos jovens." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/13873.
Full textSuccinic semialdehyde dehydrogenase (SSADH) deficiency and tyrosinemia type II are characterized by predominant tissue and blood accumulation of γ-hydroxybutyric acid (GHB) and tyrosine, respectively. Patients with SSADH deficiency and tyrosinemia type II present neurological signs and symptoms. Although mechanisms of brain damage remain unclear, they are probably related to the accumulation of GHB or tyrosine leading to possible noxious effects on central nervous system (CNS) development in those patients. Considering that the damaging consequences of oxidative stress have been implicated in a variety of disorders of CNS, the effect of GHB and L-tyrosine were investigated on some oxidative stress parameters in cerebral cortex homogenates of young rats. The in vitro and in vivo effects of GHB, or its precursor 1,4-butanediol (1,4-BD), were similar. It was observed that GHB or 1,4-BD impairs non-enzymatic antioxidant defenses and induces lipid peroxidation. On the other hand, the in vitro and in vivo effects of L-tyrosine were different. Oxidative damage to DNA was promoted while non-enzymatic and enzymatic antioxidant defenses, and thiol-disulfide redox state (SH/SS ratio) were markedly diminished by L-tyrosine in vitro. In contrast, the acute administration of L-tyrosine causes lipid peroxidation and protein oxidation, decreases non-enzymatic antioxidant defenses, alters SH/SS ratio and stimulates glucose-6-phosphate dehydrogenase activity. Taken together, it may be presumed that GHB and L-tyrosine elicit oxidative stress in cerebral cortex of young rats. If these effects also occur in the brain of patients affected by SSADH deficiency or tyrosinemia type II, it is possible that oxidative stress may contribute, at least in part, to the neurological dysfunction characteristic of these diseases.
Miyaguti, Rafael Mitsuo. "Oxidação enzimática de soluções fenólicas com tirosinase imobilizada em quitosana." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/9/9135/tde-29092011-160712/.
Full textThe phenolic compounds when in high concentrations in water are extremely dangerous pollutants and difficult to be eliminated even by conventional methods such as the microbiological bioremediation with activated sludge and physico-chemical methods. Phenols are present in many industrial effluents and is necessary to develop new and effective processes for the treatment of that effluents and, if possible, environmentally friendly. This research aimed the degradation of phenolic pollutants in aqueous solutions by enzymatic oxidation with tyrosinase immobilized in chitosan. Phenols such as 4-chlorophenol, 4-cresol, 4-nitrophenol and phenol, had been used in assays of enzymatic oxidation in an agitated reactor, in dynamic regime, in a batch process, temperature of 45°C and three values of enzymatic concentration ( 40, 60 and 80 U/ml). In addition, three forms of chitosan had been used in enzymatic immobilization and applied in the processes of oxidation of phenol: pellets, flakes and small particles of chitosan. Tyrosinase was efficient in the degradation of phenol, 4-cresol and 4-chlorophenol, reducing significantly the concentration of these pollutants in aqueous solutions. However, tyrosinase did not oxidized 4-nitrophenol. It was verified that the effect of some substitutes and their position in the aromatic ring has a direct influence on the activity of the enzyme during the oxidative reactions involving phenolic compounds. Although this study has shown good results in the removal of some phenolic compounds in aqueous solutions through the oxidation of such pollutants by the tyrosinase immobilized on chitosan, the enzyme-support did not present the same efficiency in subsequent assays, in which we studied the reuse of the immobilized enzyme.
Vermeer, Lydia Maria Mexas. "Covalent modification and inhibition of tyrosine hydroxylase by 3,4-dihydroxyphenylacetaldehyde, an endogenously produced neurotoxin relevant to Parkinson's disease." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/1923.
Full textChaumais, Marie-Camille. "Innovations thérapeutiques non vasodilatatrices dans l'hypertension artérielle pulmonaire." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA114820/document.
Full textPulmonary arterial hypertension (PAH) corresponds to a group of diseases characterized by a vascular obstruction due to vasoconstriction, cellular proliferation and in situ thrombosis, leading to a progressive increase in pulmonary vascular resistances. New knowledge in the PAH management were performed in the last few years, specifically for vasodilators. However, none of those treatments cure the disease and new drugs are still needed. Molecules targeting cellular proliferation induced by tyrosine kinases receptors (TKR) activation or oxidative stress (OS) seem to be potential therapeutic innovations. However, knowledge on OS in PAH is not enough accomplished in PAH to target accurately this pathophysiologic pathway. Similarly, tyrosine kinase inhibitors have shown efficacy in PAH management but associated with severe adverse events as cardiac toxicity. In this study, mechanism of action of OS in pathophysiology of PAH was detailed and identification of TKR involved in vascular remodeling was completed in order to find efficient therapeutics with a favorable risk benefit ratio for PAH patient
Secor, Jordan Douglas. "Phytochemical Antioxidants Induce Membrane Lipid Signaling in Vascular Endothelial Cells." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338391553.
Full textKnebel, Axel [Verfasser]. "Hemmung von Protein-Tyrosin-Phosphatasen als Mechanismus der Wachstumsfaktor-Rezeptor- Aktivierung durch UV, oxidativen Stress und Organometalle / Axel Knebel." Karlsruhe : KIT-Bibliothek, 1997. http://d-nb.info/1103572121/34.
Full textShalbaf, Mohammad. "More evidence for H2O2-mediated oxidative stress in vitiligo-increased epidermal DNA damage / repair." Thesis, University of Bradford, 2009. http://hdl.handle.net/10454/4326.
Full textShalbaf, Mohammad. "More evidence for H₂O₂-mediated oxidative stress in vitiligo-increased epidermal DNA damage / repair." Thesis, University of Bradford, 2009. http://hdl.handle.net/10454/4326.
Full textLykourinou, Vasiliki. "Copper and iron complexes of linear and crosslinked polymers as catalysts for phosphoester hydrolysis and oxidative transformation of phenolic and catecholic substrates." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001845.
Full textRibeiro, Márcia Vaz. "Elicitores abióticos no estresse oxidativo e na expressão de gene da rota de betacianina em Alternanthera philoxeroides (Mart.) Griseb." Universidade Federal de Pelotas, 2011. http://repositorio.ufpel.edu.br/handle/ri/2051.
Full textThe medicinal Alternanthera (Amaranthaceae) species, such as A. philoxeroides, present a great variety of bioactive compounds, among which are the betacyanins, nitrogen pigments that belong to the betalains class. These compounds are widely used as additives for food and drugs, due to their antioxidant action and lack of toxicity, which have already been proven. Techniques have been developed in order to improve productivity and performance of this pigment, one of those is the use of in vitro elicitors or in vivo stressing agents. Both have an important role in the transduction process of signals that regulate the defense genes in plants, acting as stimulators of production or degradation of several primary and secondary metabolites. This work aimed to assess, in A. philoxeroides plants, the growth and production characteristics of betacyanin in in vitro plants; the levels of photosynthetic pigments, betacyanins, lipid peroxidation and antioxidant enzymes activity in in vivo plants under salt stress, and also to quantify the level of betacyanin and the 5GT-DBs gene expression in the biosynthetic route of this compound in in vitro plants submitted to elicitation by NaCl and by tyrosine. For this, three trials were conducted. In the first one, A. philoxeroides explants were inoculated in MS medium with increasing NaCl concentrations (0, 50, 100, 150, 200 and 250 mM) for 35 days. In the second one, plants from in vitro cultures were acclimatized in greenhouses and irrigated with a sodium chloride solution (0, 200 and 400 mM) for 30 days. The third trial had two essays, one composed of in vitro A. philoxeroides plants in a liquid MS medium in vermiculite substrate for 35 days. After this period, a NaCl solution (400 mM) was added to the medium and the shoots were collected after 0, 12, 24, 36 and 48 hours of exposure. In the second one, nodal segments were inoculated in MS medium with and without tyrosine (0 e 75 µM), and its aerial parts were collected after 35 days. In the growth analysis, reduction of the averages was observed for the following variables: height, number of shoots, number of sprouts and root number and length; for the plants that have grown in the sodium chloride medium. The highest concentrations of betacyanins were found in the stalks of plants from MS medium, with 50 mM of NaCl. After 30 days of in vivo cultivation, the levels of chlorophyll a, chlorophyll b and carotenoids decreased as the salt concentration increased, while the reason of chlorophyll a/b in plants submitted to a higher salt concentration presented a difference in comparison to the control. Higher levels of betacyanin were observed on stalks, when compared to the leaves, in the highest salt concentrations. On the leaves, there was a significant increase of lipid peroxidation and superoxide dismutase activity. On the roots, there was an increase of enzymes catalase and ascorbate peroxidase. Regarding the analysis of differential expression (qRT-PCR), it was possible to observe that from 12 to 24 hours of salt stress, the 5-GT gene expression firstly increased, then there was a decrease in 36 hours and a new increase in 48 hours. The 5-GT gene also showed increased expression as a response to tyrosine. It was possible to conclude that A. philoxeroides elicited in vitro with sodium chloride present a decrease of the assessed morphological parameters, but in low concentrations betacyanin synthesis is stimulated. Salt stress causes greater degradation in the photosynthetic pigments, increment of betacyanin synthesis in stalks and damage to the cell membranes of the leaves. The increase of antioxidant enzymes activity stimulated the protective system against oxidative stress on in vivo A. philoxeroides plants. It is suggested that in this species, the enzyme bethanidine 5-Oglucosyltransferase reaches its highest expression in 48 hours of exposure to salt elicitation and also when grown in a medium containing tyrosine.
As espécies medicinais do gênero Alternanthera (Amaranthaceae) como A. philoxeroides apresentam uma variedade de compostos bioativos, entre eles as betacianinas, que são pigmentos nitrogenados pertencentes à classe das betalaínas. Esses compostos são amplamente utilizados como aditivos de produtos alimentícios e medicamentos devido à sua comprovada ação antioxidante e ausência de toxicidade. Técnicas têm sido desenvolvidas para aprimorar a produtividade e o rendimento deste pigmento, sendo uma delas o uso de elicitores in vitro ou agentes estressantes in vivo. Ambos apresentam um importante papel no processo de transdução de sinais que regulam os genes de defesa nas plantas, agindo como estimuladores para a produção e ou degradação de diversos metabólitos, tanto primários quanto secundários. Assim, o objetivo do presente trabalho foi avaliar em plantas de A. philoxeroides, as características de crescimento e produção de betacianina em plantas cultivadas in vitro; os teores dos pigmentos fotossintéticos, betacianinas, peroxidação lipídica e atividade de enzimas antioxidantes em plantas cultivadas in vivo, sob estresse salino, além de, quantificar o teor de betacianina e a expressão do gene 5GT-DBs envolvido na rota biossintética, deste composto, em plantas in vitro submetidas à elicitação por NaCl e pelo aminoácido tirosina. Para isso, foram conduzidos três experimentos. No primeiro, explantes de A. philoxeroides foram inoculados em meio MS, com concentrações crescentes de NaCl (0, 50, 100, 150, 200 e 250 mM), durante 35 dias. No segundo, plantas provenientes da cultura in vitro foram aclimatizadas em casa de vegetação e irrigadas com solução de cloreto de sódio (0, 200 e 400 mM), por 30 dias. O terceiro experimento contou com dois ensaios, sendo o primeiro composto de plantas de A. philoxeroides cultivadas in vitro, em meio MS líquido, no substrato vermiculita, durante 35 dias. Após esse período, foi adicionada ao meio, solução de NaCl (400 mM) e coletada a parte aérea das plantas após 0, 12, 24, 36 e 48 horas de exposição ao sal, Já o segundo, segmentos nodais foram inoculados em meio MS, na presença e ausência de tirosina (0 e 75 µM), tendo sua parte aérea coletada após 35 dias de cultivo. Nas análises de crescimento observou-se redução das médias para as variáveis altura, número de gemas, número de brotos e no número e comprimento de raiz, nas plantas crescidas nos meios contendo cloreto de sódio. As maiores concentrações de betacianinas foram encontradas nos caules de plantas cultivadas em meio MS com 50 mM de NaCl. Após 30 dias de cultivo in vivo os teores de clorofilas a, clorofila b, e carotenóides decresceram à medida que aumentou a concentração de sal, enquanto a razão clorofila a/b das plantas submetidas à maior concentração de sal apresentou
Moreira, Ana Sofia Pereira. "Study of modifications induced by thermal and oxidative treatment in oligo and polysaccharides of coffee by mass spectrometry." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17074.
Full textOs polissacarídeos são os componentes maioritários dos grãos de café verde e torrado e da bebida de café. Os mais abundantes são as galactomananas, seguindo-se as arabinogalactanas. Durante o processo de torra, as galactomananas e arabinogalactanas sofrem modificações estruturais, as quais estão longe de estar completamente elucidadas devido à sua diversidade e à complexidade estrutural dos compostos formados. Durante o processo de torra, as galactomananas e arabinogalactanas reagem com proteínas, ácidos clorogénicos e sacarose, originando compostos castanhos de alto peso molecular contendo nitrogénio, designados de melanoidinas. As melanoidinas do café apresentam diversas atividades biológicas e efeitos benéficos para a saúde. No entanto, a sua estrutura exata e os mecanismos envolvidos na sua formação permanecem desconhecidos, bem como a relação estrutura-atividade biológica. A utilização de sistemas modelo e a análise por espectrometria de massa permitem obter uma visão global e, simultaneamente, detalhada das modificações estruturais nos polissacarídeos do café promovidas pela torra, contribuindo para a elucidação das estruturas e mecanismos de formação das melanoidinas. Com base nesta tese, oligossacarídeos estruturalmente relacionados com a cadeia principal das galactomananas, (β1→4)-Dmanotriose (Man3), e as cadeias laterais das arabinogalactanas, (α1→5)-Larabinotriose (Ara3), isoladamente ou em misturas com ácido 5-Ocafeoilquínico (5-CQA), o ácido clorogénico mais abundante nos grãos de café verde, e péptidos compostos por tirosina e leucina, usados como modelos das proteínas, foram sujeitos a tratamento térmico a seco, mimetizando o processo de torra. A oxidação induzida por radicais hidroxilo (HO•) foi também estudada, uma vez que estes radicais parecem estar envolvidos na modificação dos polissacarídeos durante a torra. A identificação das modificações estruturais induzidas por tratamento térmico e oxidativo dos compostos modelo foi feita por estratégias analíticas baseadas principalmente em espectrometria de massa, mas também em cromatografia líquida. A cromatografia de gás foi usada na análise de açúcares neutros e ligações glicosídicas. Para validar as conclusões obtidas com os compostos modelo, foram também analisadas amostras de polissacarídeos do café obtidas a partir de resíduo de café e café instantâneo. Os resultados obtidos a partir dos oligossacarídeos modelo quando submetidos a tratamento térmico (seco), assim como à oxidação induzida por HO• (em solução), indicam a ocorrência de despolimerização, o que está de acordo com estudos anteriores que reportam a despolimerização das galactomananas e arabinogalactanas do café durante a torra. Foram ainda identificados outros compostos resultantes da quebra do anel de açúcares formados durante o tratamento térmico e oxidativo da Ara3. Por outro lado, o tratamento térmico a seco dos oligossacarídeos modelo (individualmente ou quando misturados) promoveu a formação de oligossacarídeos com um maior grau de polimerização, e também polissacarídeos com novos tipos de ligações glicosídicas, evidenciando a ocorrência de polimerização através reações de transglicosilação não enzimática induzidas por tratamento térmico a seco. As reações de transglicosilação induzidas por tratamento térmico a seco podem ocorrer entre resíduos de açúcares provenientes da mesma origem, mas também de origens diferentes com formação de estruturas híbridas, contendo arabinose e manose como observado nos casos dos compostos modelo usados. Os resultados obtidos a partir de amostras do resíduo de café e de café instantâneo sugerem a presença de polissacarídeos híbridos nestas amostras de café processado, corroborando a ocorrência de transglicosilação durante o processo de torra. Além disso, o estudo de misturas contendo diferentes proporções de cada oligossacarídeo modelo, mimetizando regiões do grão de café com composição distinta em polissacarídeos, sujeitos a diferentes períodos de tratamento térmico, permitiu inferir que diferentes estruturas híbridas e não híbridas podem ser formadas a partir das arabinogalactanas e galactomananas, dependendo da sua distribuição nas paredes celulares do grão e das condições de torra. Estes resultados podem explicar a heterogeneidade de estruturas de melanoidinas formadas durante a torra do café. Os resultados obtidos a partir de misturas modelo contendo um oligossacarídeo (Ara3 ou Man3) e 5-CQA sujeitas a tratamento térmico a seco, assim como de amostras provenientes do resíduo de café, mostraram a formação de compostos híbridos compostos por moléculas de CQA ligadas covalentemente a um número variável de resíduos de açúcar. Além disso, os resultados obtidos a partir da mistura contendo Man3 e 5-CQA mostraram que o CQA atua como catalisador das reações de transglicosilação. Por outro lado, nas misturas modelo contendo um péptido, mesmo contendo também 5-CQA e sujeitas ao mesmo tratamento, observou-se uma diminuição na extensão das reações transglicosilação. Este resultado pode explicar a baixa extensão das reações de transglicosilação não enzimáticas durante a torra nas regiões do grão de café mais ricas em proteínas, apesar dos polissacarídeos serem os componentes maioritários dos grãos de café. A diminuição das reações de transglicosilação na presença de péptidos/proteínas pode dever-se ao facto de os resíduos de açúcares redutores reagirem preferencialmente com os grupos amina de péptidos/proteínas por reação de Maillard, diminuindo o número de resíduos de açúcares redutores disponíveis para as reações de transglicosilação. Além dos compostos já descritos, uma diversidade de outros compostos foram formados a partir dos sistemas modelo, nomeadamente derivados de desidratação formados durante o tratamento térmico a seco. Em conclusão, a tipificação das modificações estruturais promovidas pela torra nos polissacarídeos do café abre o caminho para a compreensão dos mecanismos de formação das melanoidinas e da relação estrutura-atividade destes compostos.
Polysaccharides are the major components of green and roasted coffee beans, and coffee brew. The most abundant ones are galactomannans, followed by arabinogalactans. During the roasting process, galactomannans and arabinogalactans undergo structural modifications that are far to be completely elucidated due to their diversity and complexity of the compounds formed. During the roasting process, galactomannans and arabinogalactans react with proteins, chlorogenic acids, and sucrose, originating high molecular weight brown compounds containing nitrogen, known as melanoidins. Several biological activities and beneficial health effects have been attributed to coffee melanoidins. However, their exact structures and the mechanisms involved in their formation remain unknown, as well as the structure-biological activity relationship. The use of model systems and mass spectrometry analysis allow to obtain an overall view and, simultaneously, detailed, of the structural modifications in coffee polysaccharides promoted by roasting, contributing to the elucidation of the structures and formation mechanisms of melanoidins. Based on this thesis, oligosaccharides structurally related to the backbone of galactomannans, (β1→4)-D-mannotriose, and the side chains of arabinogalactans, (α1→5)-Larabinotriose, alone or in mixtures with 5-O-caffeoylquinic acid, the most abundant chlorogenic acid in green coffee beans, and dipeptides composed by tyrosine and leucine, used as models of proteins, were submitted to dry thermal treatments, mimicking the coffee roasting process. The oxidation induced by hydroxyl radicals (HO•) was also studied, since these radicals seem to be involved in the modification of the polysaccharides during roasting. The identification of the structural modifications induced by thermal and oxidative treatment of the model compounds was performed mostly by mass spectrometry-based analytical strategies, but also using liquid chromatography. Gas chromatography was used in the analysis of neutral sugars and glycosidic linkages. To validate the conclusions achieved with the model compounds, coffee polysaccharide samples obtained from spent coffee grounds and instant coffee were also analysed. The results obtained from the model oligosaccharides when submitted to thermal treatment (dry) or oxidation induced by HO• (in solution) indicate the occurrence of depolymerization, which is in line with previous studies reporting the depolymerization of coffee galactomannans and arabinogalactans during roasting. Compounds resulting from sugar ring cleavage were also formed during thermal treatment and oxidative treatment of Ara3. On the other hand, the dry thermal treatment of the model oligosaccharides (alone or when mixed) promoted the formation of oligosaccharides with a higher degree of polymerization, and also polysaccharides with new type of glycosidic linkages, evidencing the occurrence of polymerization via non-enzymatic transglycosylation reactions induced by dry thermal treatment. The transglycosylation reactions induced by dry thermal treatment can occur between sugar residues from the same origin, but also of different origins, with formation of hybrid structures, containing arabinose and mannose in the case of the model compounds used. The results obtained from spent coffee grounds and instant coffee samples suggest the presence of hybrid polysaccharides in these processed coffee samples, corroborating the occurrence of transglycosylation during the roasting process. Furthermore, the study of mixtures containing different proportions of each model oligosaccharide, mimicking coffee bean regions with distinct polysaccharide composition, subjected to different periods of thermal treatment, allowed to infer that different hybrid and non-hybrid structures may be formed from arabinogalactans and galactomannans, depending on their distribution in the bean cell walls and on roasting conditions. These results may explain the heterogeneity of melanoidins structures formed during coffee roasting. The results obtained from model mixtures containing an oligosaccharide (Ara3 or Man3) and 5-CQA and subjected to dry thermal treatment, as well as samples derived from spent coffee grounds, showed the formation of hybrid compounds composed by CQA molecules covalently linked to a variable number of sugar residues. Moreover, the results obtained from the mixture containing Man3 and 5-CQA showed that CQA acts as catalyst of transglycosylation reactions. On the other hand, in the model mixtures containing a peptide, even if containing 5-CQA and subjected to the same treatment, it was observed a decrease in the extent of transglycosylation reactions. This outcome can explain the low extent of non-enzymatic transglycosylation reactions during roasting in coffee bean regions enriched in proteins, although polysaccharides are the major components of the coffee beans. The decrease of transglycosylation reactions in the presence of peptides/proteins can be related with the preferential reactivity of reducing residues with the amino groups of peptides/proteins by Maillard reaction, decreasing the number of reducing residues available to be directly involved in the transglycosylation reactions. In addition to the compounds already described, a diversity of other compounds were formed from model systems, namely dehydrated derivatives formed during dry thermal treatment. In conclusion, the identification of the structural modifications in coffee polysaccharides promoted by roasting pave the way to the understanding of the mechanisms of formation of melanoidins and structure-activity relationship of these compounds.
Karisch, Robert. "Global Proteomic Assessment of Classical Protein-tyrosine Phosphatases." Thesis, 2013. http://hdl.handle.net/1807/65510.
Full textBergeron, Alexandre. "Caractérisation de l'oxydoréduction de la protéine tyrosine phosphatase 1B dans la signalisation du récepteur à l'EGF." Thèse, 2017. http://hdl.handle.net/1866/21022.
Full textChou, Yu-Ching, and 周玉青. "Study on the anti-oxidation and tyrosinase-inhibiting activities of scopoletin." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/54432853685093037652.
Full text弘光科技大學
化妝品科技研究所
97
Scopoletin (6-methoxy-7-hydroxycoumarin) is a pharmacologically active coumarin compound that has been isolated from several traditional Chinese herbs, such as Lycium chinense Mill and Angelicae dahuricae Radix. It also has been widely existed in the plant, such as Rutaceae Dictamnus、Rutaceae Murrayapaniculata. Several studies have shown that scopoletin show hepatoprotective activity, antihypertension, anti-bacteriae, down fever and relieve pain. In addition, It was shown that scopoletin show the anti-hemoglutination effect on the domestic rabbit. The aim of this research is to evaluate whether scopoletin whether has antioxidation and white efficacy. Previous study reported that scopoletin has antioxidation activity. However, there is no report about interaction between scopoletin and other antioxidants such as vitamin C or vitamin E. Therefore, we aim to study possible synergistic antioxidation effects between scopoletin and vitamin C or vitamin E. Antioxidation activity was assayed by determining the DPPH radical scavenging activity , total phenol content, ABTS+ radical cation decoloriation and reducing power. The experimental results showed that DPPH radical capture ability is higher along with scopoletin concentration. The capture ability of scopoletin is also more obvious when combined with vitamin C or vitamin E. When scopoletin was combined with vitamin C, the total phenol content also increased in a dose-dependent pattern, whereas similar result was not found in the case of vitamin E. Additionally, scopoletin and vitamin C also showed remarkable synergistc effects on reducing power and the elimination of ABTS+. Afterwards, the effects of scopoletin on mushroom tyrosinase activity, intracellular tyrosinase activity and melanin content of murine B16F10 melanoma cells were evaluated. Kojic acid was used as a positive standard in the above experiments. The results showed that high concentration of scopoletin(2 mM~10 mM)could suppress mushrom tyrosinase activity in a dose-dependent pattern. However, when scopoletin combined with kojic acid, there is no obvious synergistic effect on the inhibition of tyrosinase activity. Interestingly, intracellular tyrosinase activity of B16F10 cells was suppressed by low concentration of scopoletin(25 μM, 50 μM, 100μM). Besides, the melanin content in B16F10 cells was also decreased by scopoletin in a dose-dependent pattern. Afterwards, we also evaluated the effects of scopoletin on protein content of melanin related proteins- Tyrosinae、Tyrosinase-related protein-1(TRP-1) and Tyrosinase-related protein-2(TRP-2) by western blot. The intracellular tyrosinase、TRP-2 was also decreased by scopoletin in a dose-dependent pattern. The further work will elucidate the whitening mechanism of scopoltin, and we will also evaluate the possibility of scopoletin applied in the antioxidation and whitening cosmetic formulations.
Huang, Chun-Ling, and 黃純玲. "Evaluation of anti-tyrosinase activity and the anti-oxidation of Chinese herb extracts." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/58828229816531815313.
Full text中華科技大學
健康科技研究所
102
Abstract Recently, natural skin care products and cosmetics are popular. Therefore, biotechnologycombined with Chinese herbal medicine has the large potential. In the past, many researchers screened many new ingredients to inhibit tyrosinase activity and increase antioxidant capacity from Chinese herbal plantsIn this experiment, Walnuts, Moutan, and Asparticwere selected and they were extracted by distilled water, 95% ethanol, 50% ethanol, 100% ethyl acetate and 50% ethyl acetate.These extracted liquid was then fermented by Bifidobacterium bifidumat different times.Some chemical properties including anti-tyrosinase activity, reducing power and scavenging activity of DPPH radical were measured.Additionally, cytotoxicity was evaluated by the survival rate of CCD-966SK cells. HPLC chromatogram reveled that the different compounds were existed in the liquid fermented or not by B. bifidum. The 100% anti-tyrosinase activity was found in the operating condition (Aspartic extracted by distilled water and fermented for 12 hours).DPPH scavenging was achieved 89.4% when Moutanextracted by 95% ethanol and then fermented for 8 hours. In conclusion, Moutanand Asparticextracted by solvents and then fermented by B. bifidum have potential as whitening agent and antioxidants. Keywords: whitening, anti-oxidation, Aspartic, Moutan, lactic acid bacteria, tyrosinase
Laufer, Zsanett. "Occurrence and properties of the multicopper oxidases laccase and tyrosinase in lichens." Thesis, 2012. http://hdl.handle.net/10413/9909.
Full textThesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.
Cheng, Wen-Yen, and 鄭文晏. "Anti-oxidative and Anti-tyrosinase Activities of Extracts of Purple Coneflower Seed." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/43253972900722617939.
Full text大葉大學
生物產業科技學系
96
The three caffeic acid derivatives contents, anti-oxidative and anti-tyrosinase activities of extracts with 100% pure water (WEs), and 10%, 40%, 70% ethanol (0.1EtEs, 0.4EtEs, 0.7EtEs, respectively), and 10%, 40% and 70% glycerol (0.1GlEs, 0.4 GlEs, 0.7GlEs, respectively) of the powders (PCfSPs) of purple coneflower seeds produced in Taiwan were investigated in this study. The maximum caffeic acid derivatives contents (1.13% dried weight) was obtained from the freeze-dried 0.7EtEs of PCfSPs, while those (90.6 g/mL 70% glycerol) was obtained from the 0.7GlEs of PCfSPs for glycerol extraction. Among the WEs and EtEs of PCfSPs, only the freeze-dried 0.7EtEs had the best DPPH-scavenging effect (IC50 activity: 97g 0.7EtEs/mL), while the 0.7GlEs had the strongest effect (IC50: 1.89% 0.7GlEs) for glycerol extraction. In general, the freeze-dried WEs and EtEs had better anti-tyrosinase activities than those of the hot-dried extracts. The anti-tyrosinase activities increased as increasing the extraction concentrations of ethanol. Among the WEs and EtEs of PCfSPs, only the freeze-dried 0.7EtEs had the best anti-tyrosinase activity (IC50: 625g 0.7EtEs/mL), while the 0.7GlEs had the strongest activity (IC50: 2.32% 0.7GlEs).
Zhi, Chen Yong, and 陳勇智. "Study on Anti-oxidative and Anti-tyrosinase Activities of Polygonum Cuspidatum Extracts." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/73280990336275937260.
Full text大葉大學
生物產業科技學系
95
The resveratrol contents, anti-oxidative ( DPPH-free-radical-scavenging effect ) and anti-tyrosinase activities of Polygonum cuspidatum ( one of Chinese traditional medicine ) extracts with 100% pure water ( Wes ) and 10% and 70% ethanol solutions ( 0.1 EtEs and 0.7 EtEs, respectively ) were investigated in this study. The maximum extract content ( 30% extraction yield ) and resveratrol ( 1.57% dried weight ) was obtained from the freeze-dried 0.7 EtEs of P. cuspidatum. Among the P. cuspidatum extracts, only the freeze-dried 0.7 EtEs had strong DPPH-scavenging effects or anti-oxidative activities, while the activities of the freeze-dried 0.7 EtEs first gradually decreased to a certain value as increasing their addition concentrations or resveratrol contents, and then increased as increasing the concentrations or contents. For the other P. cuspidatum extracts, the anti-oxidative activities first increased and then decreased to some certain values as increasing their addition concentrations or resveratrol contents. Except that the tyrosinase relative activities of the hot-dried WEs and 0.1 EtEs were kept at 80%~90%, the freeze-dried 0.7 EtEs also had stronger anti-tyrosinase activities than the others. However, the tyrosinase relative activities started decreasing from original 70% or the anti-tyrosinase activities became much significant and effective when the addition concentrations or resveratrol contents of the freeze-dried 0.7 EtEs were over 1000 g/mL or 15.7 g, respectively. In this study, only the freeze-dried 0.7 EtEs had the higher extract and resveratrol contents and stronger anti-oxidative anti-tyrosinase activities than the others.
Lou, Yi-Wei, and 羅翊偉. "Intrinsic oxidative stress regulates enzymatic activity of protein tyrosine phosphatases and FAK-mediated signal transduction in Ras-transformed fibroblasts." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/83059613824214614392.
Full text國立臺灣大學
生化科學研究所
93
Reactive oxygen species (ROS) have emerged as intracellular signaling molecules in multiple cellular processes such as proliferation, apoptosis, and senescence. The signaling properties of ROS are largely due to the reversible oxidation of redox-sensitive target proteins, particularly protein tyrosine phosphatases (PTPs). Recent studies suggested that the abnormally high levels of cellular ROS production are concurrent with the development of human diseases such as cancers. We examined the role of ROS in the control of signal transduction in Ras- and Src-transformed NIH-3T3 cells which constitutively produce more ROS and possess more active tyrosine phosphorylation signals than parental NIH-3T3 cell. Treatment of transformed cells with diphenyleneiodonium (DPI), a NADPH oxidase (Nox) inhibitor, led to the suppression of cellular ROS production. Under this condition, we found that the activity of endogenous PTPs was elevated, whereas the tyrosine phosphorylation level of cellular proteins was decreased. Such an effect was more pronounced in Ras-transformed cells, compared with that in Src-transformed cells, suggesting that Ras-mediated signal transduction is essentially ROS-dependent. This hypothesis was further investigated. In Ras-transformed cells treated with DPI, a 120 kDa protein, which showed a significant decrease of tyrosine phosphorylation, was subsequently identified as focal adhesion kinase (FAK). Upon the inhibition of cellular ROS production, FAK was dephosphorylated at tyrosine 397 (Tyr397), an integrin-induced auto-phosphorylation site whose phosphorylation activates FAK and enhances cell migration. Treatment of DPI also led to the decrease of phosphorylation levels of Tyr576, Tyr577, Tyr861 and Tyr925 of FAK, concurrent with the decreased kinase activity of Src that recognizes and phosphorylates those Tyr residues in FAK. We also observed that the overexpression of dominant negative Rac1N17, which has been shown to block Nox activity, resulted in the dephosphorylation of FAK and Src. Furthermore, we showed that Ras-transformed cells lost their membrane protrusions in a time-dependent manner in response to DPI treatment, concomitant with the reactivation of cellular PTPs that were originally undergoing reversible oxidation. Our data thus suggested that the Ras-mediated migration signal is regulated by the ROS-dependent activation of FAK and Src through constitutive oxidation and inactivation of endogenous PTPs.
Kao, Jui-Chun. "TYROSINE KINASE INHIBITOR AG490 INDUCES GRP78 AND GRP94 IN 9L RBT CELLS: INVOLVEMENT OF INTRACELLULAR CALCIUM DISTURBANCES AND OXIDATIVE STRESS." 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0016-1303200709470262.
Full textKao, Jui-Chun, and 高睿君. "TYROSINE KINASE INHIBITOR AG490 INDUCES GRP78 AND GRP94 IN 9L RBT CELLS: INVOLVEMENT OF INTRACELLULAR CALCIUM DISTURBANCES AND OXIDATIVE STRESS." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/44770709179270715563.
Full text國立清華大學
生物科技研究所
95
Previously, our group found that geldanamycin (GA) with sublethal dose provokes the ER stress in rat brain tumour 9L (9L RBT) cells, which followed by the generation of reactive oxygen species (ROS). However, the effect of GA on the unfolded protein response (UPR) signaling pathway remains unclear. Recently, activation of JAK/STAT pathway has been observed in response to generation of intracellular ROS and exogenous hydrogen peroxide (H2O2). Here, we investigated the effect of AG490, the specific inhibitor of Janus kinase-2 (JAK2), on the expression of grp78 coding for ER stress protein and the mechanistic relationship of GA signaling to ER stress. The mRNA and protein level of grp78 and grp94 were examined by real-time quantitative RT-PCR, Western blotting analysis and metabolic labeling experiment in 9L RBT cells treated with GA or AG490. In this study, we firstly discovered that AG490 only could specifically transactivate the ER-resident molecular chaperones GRP78 and GRP94 in 9L RBT cells. In addition, calcium chelator BAPTA-AM, mitochondrial uniporter inhibitor ruthenium red (RR), antioxidant N-acetylcysteine (NAC), and the inhibitor of mitochondrial PT pore, cyclosporin A (CyA), abolished the grp78 and grp94 induction by AG490. Therefore, it suggests that intracellular calcium disturbances and oxidative stress are involved in AG490-induced ER stress. Furthermore, serine/threonine kinase inhibitor H7, PKA inhibitor KT5720, and additional PKC isozyme-selective inhibitors including Gö6983 and Gö6976 could diminished the AG490-induced upregulation of grp78 and grp94 genes. However, the similar suppression effect of Gö6983 and Gö6976 was not observed on the GA-mediated induction of grp78 and grp94 mRNA. Thus, we suggest that the signaling pathway of AG490-induced ER stress response might different from GA. In conclusion, AG490, as an ER stress inducer, might evoke intracellular calcium disturbances and generation of ROS, which lead to activation of cPKC and PKA for upregulation of grp78 and grp94 genes in 9L RBT cells.
Yang, Chun-Yi, and 楊君怡. "Cysteine sulfonation induces ubiquitin-dependent proteolysis of protein tyrosine phosphatases: A molecular basis for protein quality control under oxidative stress." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/4fdwf9.
Full text國立臺灣大學
生化科學研究所
106
Reactive oxygen species (ROS) has been shown to play a critical role in the development and progression of cardiac pathophysiology. Protein is one of the prime targets of cellular ROS generated in cardiomyocytes. Among the 20 common amino acid, cysteine (Cys) residue, which has a remarkably low pKa characteristic, is highly susceptible to oxidation. Identification of the redox role of thiol modifications has gained significant importance because Cys residue plays an important role in protein function under pathophysiological conditions. Here, our study focuses on the redox-dependent regulation of Cys-sulfonation (SO3H), which belongs irreversible oxidation, on protein tyrosine phosphatases (PTPs). Because of its high nucleophilic property, catalytic Cys residue within PTPs is the direct targets of cellular ROS. To investigate the effect of ROS-induced Cys-sulfonation on PTPs and the mechanism of proteolysis in protein quality control machinery. Using the antibody-based method that could detect protein Cys-sulfonation, we found that endogenous PTPs already oxidized irreversibly and undergoing proteasome-mediated degradation in H9c2 cells. Protein tyrosine phosphatase 1B (PTP1B) is one of PTPs oxidation well-studied, so we chose PTP1B as our experiment model. Upon H2O2 stimuli, through the in vivo and in vitro immunoprecipitation assays, we found that PTP1B catalytic Cys215 residue was sulfonated and it facilitated PTP1B for ubiquitination and proteolysis. Inhibition of PTP1B oxidation by site-directed mutagenesis of PTP1B at active-site Cys215 abrogates the effects of protein ubiquitination and degradation on PTP1B. Through the high-throughput Yeast proteome chips, we identified CDC53, which has homology to human Cul1 E3 ligase, could strongly interact with the chemically synthesized peptide containing Cys-sulfonation. Subsequent investigation with the dominant-negative construct of Cul1 E3 ligase suggested that PTP1B serve as the substrate for Cul1 via Cys-sulfonation recognition. Impairment of Cul1-mediated degradation of Cys-sulfonated PTPs potentiated cardiotoxicity. The findings of this study provide important insight into how biologically significant Cys oxidation directs myocardial protein turnover through ubiquitin/proteasome-mediated degradation.
Khadaroo, Rachel G. "The cellular and molecular mechanisms regulating oxidative stress-induced priming of the macrophage : the role of the Src family of tyrosine kinases." 2004. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=94768&T=F.
Full textWang, Chung-Jen, and 王重仁. "Studies on anti-oxidative activities and anti-tyrosinase properties of the microwave Chinese herbs aqueous extracts." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/25564582148609158368.
Full text嘉南藥理科技大學
生物科技系暨研究所
91
Microwave aqueous extracts (MAE) from twelve Chinese herbs and fifteen commercial pure compounds were evaluated for their (1) melanin biosynthesis anti-oxidative activities by tyrosinase inhibition, (2) nitric oxide (NO) scavenging activities by SNP, (3) radical scavenging effects by the DPPH and ( 4) peroxynitrite scavenging activities by the SNP / H2O2 / luminal chemiluminescence’s methods. The results of our investigation show that glycyrrhizae radix for the preliminary assay optimal tyrosinase inhibition (90. 73%) and NO scavenging effects (82.39%) of microwave Chinese herbs extracts can be concluded that the duration of microwave radiation is 6 min, the microwave energy is 720w. Our studies also show three Chinese herbs by MAE ( Ramulus mori, Glycyrrhizae radix and Cortex mori) exhibited high anti- tyrosinase (SC50=0.3,0.9 and 3.11mg/ml, respectively) and NO scavenging effect (SC50=0.238, 0.249 and 0.236mg/ml, respectively). On the other hands, Acanthopanax senticosus (SC50=0.755, 0.713mg/ml, respectively) and Ginkgo biloba (SC50=0.583, 0.756mg/ml, respectively) scavenged DPPH free radical and peroxynitrite production, most effectively. Commercial pure compounds (such as licorice-derived, flavonoids, antioxidants and tyrosinase inhibitors compounds) were referenced index for their anti-tyrosinase, free radical scavenging and antioxidant properties. The results indicated that under 100μM concentration, Kojic acid against tyrosinase (63.14%), Hydroquinone scavenged NO (40.17%), Catechin scavenged DPPH free radical (97.99%), and Quercetin decreased peroxynitrite production (52.25%) present more effect for bioactivities. Collectively, these data suggest that Chinese herbs by MAE maybe extract some effect such as anti-oxidative and anti-tyrosinase. Consequently, some detail bioactive mechanisms and MAE in order to isolate and identify photochemical compounds, involved in some biological activities will be studied.
Braga, Tiago Filipe Roque. "Evaluation of the antioxidant activity and antitumor activity of marine invertebrates extracts." Master's thesis, 2014. http://hdl.handle.net/10400.1/8421.
Full textA saúde Humana é tema de grande importância, merecendo assim uma enorme atenção por parte da comunidade científica. As condições ambientais às quais o Homem se encontra sujeito nos dias de hoje, como por exemplo os agravados níveis de poluição e intensos níveis de radiação UV, são por si só potenciais causadores de inúmeros distúrbios e condições perigosas que podem facilmente evoluir para doenças, muitas delas irreversíveis e até mesmo incuráveis. Em associação aos hábitos de vida pouco saudáveis de uma enorme percentagem da população como o tabaco, má nutrição, vida sedentária e o intenso nível stress a que estamos sujeitos diariamente, todos juntos contribuem de uma forma assustadora para o desenvolvimento e progressão de doenças como cancros, Alzheimer, Parkinson e uma série de outras doenças. Tal facto, gera um stress oxidativo no organismo, que como consequência trará uma série de distúrbios ou até mesmo doenças graves. Visando aumentar a esperança média de vida, fontes naturais de compostos bioativos têm sido intensamente estudadas, de forma a prevenir, retardar e até mesmo curar determinadas doenças. Inúmeros compostos bioactivos foram já isolados de frutas, vegetais, plantas e algas, essencialmente oriundos de organismos pertencentes ao Reino das plantas. Parte destes metabolitos naturais fazem ou fizeram parte de ensaios clínicos, os quais inclusive obtiveram para alguns casos obtiveram resultados bastante positivos levando á produção farmacológica. O Oceano é um dos ecossistemas mais ricos do planeta Terra, albergando uma vasta diversidade de organismos permitindo-nos um espetáculo de cor, texturas, tamanhos e diferentes complexidades. Diariamente são produzidos inúmeros metabolitos, muitos deles por descobrir, os quais apresentam as mais variadas bioatividades e aplicações medicinais. Estudos têm vindo a provar que os compostos naturais produzidos nos Oceanos são de facto uma potencial fonte para o desenvolvimento da indústria Farmacológica. Devido á sua interessante e exuberante fisiologia e adaptações ao meio ambiente os invertebrados marinhos são talvez uma das mais promissoras fontes de compostos bioativos. Muito poucos estudos foram ainda realizados nesta área e apesar de ainda existir muito por descodificar e descobrir, estudos prévios apontam para uma forte possibilidade na utilização de invertebrados marinhos como fonte de compostos bioativos. Contudo á que ter em atenção que o estudo dos organismos como fonte de compostos bioativos é ainda bastante recente, tendo sido iniciado à sensivelmente 60 anos, pelo que ainda necessita de muitas reformulações no que toca á extração de compostos. Atualmente aproximadamente 1500 metabolitos de origem marinha já foram descritos, dos quais alguns deram inclusive origem a medicamentos como: Ziconitide (Prialt™), Yondelis™ e Halaven™, bastante referenciados para a prevenção e tratamento do cancro. Sendo que os referidos medicamentos são derivados da descoberta de compostos bioativos em esponjas. Assim sendo e considerando o potencial que os invertebrados marinhos representam para a indústria farmacológica, neste trabalho foi estuda uma espécie de lesma do mar (B.leachii), a qual é considerada invasora no Mar Mediterrâneo. Com o intuito de avaliar o potencial da mesma como fonte de metabolitos naturais foram realizados diferentes ensaios, todos eles complementares, permitindo a quantificação da atividade antioxidante (Inibição do DPPH, atividade quelante do ferro e cobre, atividade redutora do ferro e a inibição do oxido nítrico), neuroprotectora, avaliando o efeito dos extratos de B.leachii na inibição enzimática (acetilcolinesterase, butirilcolinesterase e tirosinase) e ainda o seu efeito in vitro para culturas celulares, avaliando a capacidade anti-inflamatória dos extratos (avaliando a viabilidade celular após ser induzida uma resposta inflamatória pelo LPS) e o seu potencial na proteção das células contra o efeito de H2O2. Os resultados deste estudo mostram que a B. leachii apresenta uma atividade antioxidante bastante relevante. Estes resultados são bastante promissores, pois os compostos antioxidantes têm a capacidade de prevenir o stress oxidativo, que quando descontrolado despoleta a iniciação e desenvolvimento de doenças. Os extratos mostraram ainda uma elevada afinidade para inibir a tirosinase, mostrando-se assim bastante promissores para indústria da cosmética (inibindo a produção de melanina) ou até mesmo para a indústria farmacológica. Uma vez que a tirosinase está implícita na progressão de doenças neurológicas como Parkinson, devido à libertação de compostos tóxicos associados á sua atividade, extratos de B. leachii podem portanto representar uma esperança na possibilidade do desenvolvimento de tratamento da doença. Ainda referente à atividade neuroprotectora, o extrato de acetona mostrou uma enorme habilidade na inibição do óxido nítrico, apresentando assim uma potente atividade anti-inflamatória, a qual é essencial para a prevenção de doenças neurológicas. De acordo com os dados obtidos para o seu perfil de ácidos gordos, a espécie é de facto possuidora de uma considerável percentagem de ácidos polinsaturados, especialmente ómega-3, destacando-se o EPA, o que vai de encontro á sua capacidade anti-inflamatória. De uma forma geral a espécie de lesma estudada mostrou ser uma potencial fonte de metabolitos naturais os quais apresentaram as mais diversas atividades biológicas sendo possivelmente capazes de beneficiar a saúde Humana, dada a possibilidade de atuação perante determinadas doenças. Além disso este estudo demonstrou que a lesma do mar estudada apresenta um teor proteico relevante. Pelo que uma possível alimentação em recursos obtidos destes organismos pode beneficiar em muito o sistema imunitário do Homem. Os dados obtidos nesta tese de certa forma acabam por ir ao encontro da teoria que tem vindo a ser desenvolvida pela comunidade científica: Que os compostos presentes na maioria dos invertebrados marinhos na verdade são metabolitos secundários (oriundos da dieta). Finalmente o facto de se falar de uma espécie invasora, e uma vez que a espécie tem todo este potencial, os dados justificam que no âmbito do controle da sua densidade e abundância para os locais onde é invasora, em vez de simplesmente remover o excesso de biomassa, que seria depois desperdiçado, que seja feito o reencaminhamento devido da biomassa para locais onde possa ser devidamente estuda e aproveitada. Este estudo potencializa a abertura de novas portas e oportunidades para o desenvolvimento da saúde humana. Sendo um dos primeiros estudos realizados, não existem estudos comparáveis pelo que todos os resultados são válidos para descartar ou conduzir a novas oportunidades e teorias.
Nowadays diseases are evolving and progressing so quickly, every single day thousands and thousands of people die due to several untreatable conditions. The environmental that we live on is full of dangerous agents such as pollution and radioactivity, which contribute for the emerging of new diseases. Considering the risks that those conditions represent for humans health, the research community is doing a huge effort to prevent and hopefully shut down several diseases. Scientists have been using natural sources as a way to extract natural bioactive compounds, with a range of different bioactivities, which can potently be used by the pharmaceutical industry for the new drug development. Oceans are one of the more diverse ecosystems in the world. Aquatic systems are stuffed with a huge diversity of organisms where a magnificent world of colors, shapes, textures and interesting metabolites can be seen. Marine animals had evolved in a complete different environmental and for that they contain a considerable amount of bioactive compounds due to an accurate chemical defensive system, diet and other adaptations to the extreme conditions of oceans. By its interesting physiology, marine invertebrates namely sponges, tunicates, sea cucumbers and sea hare, are considered as a potential resource of bioactive compounds. In the recent years around 1500 marine natural products have been identified, 45 were tested during preclinical and clinical trials. A few of them have been approved for clinical use: this is the case of Ziconitide (Prialt™) used for the chronic pain; ecteinascidin 743 (Yondelis™) used for the treatment of ovarian cancer soft tissue sarcoma and eribulin mesylate (Halaven™) for the treatment of recurrent breast cancer. Another example is bryostatin, which was originally studied for anticancer activity and led to the development of analogues with a high potential to alleviate the symptoms related with Alzheimer’ disease. Considering the background and the urgency of the identification of new bioactive compounds, the main goal of this thesis project is to evaluate the biological activities of extracts from Bursatella leachii, which is an invasive species of sea hare in the Mediterranean. For the following extracts it was evaluated the antioxidant and neuroprotective activity using different and complementary assays. As for the antioxidant activity, it was evaluated through the RSA of DPPH, nitric oxide inhibition, metal chelating activity and iron reducing/antioxidant power. For the neuroprotective activity it was quantified the ability to inhibition toome specific enzymes and the anti-inflammatory power of the extracts. This work proved that the B. leachii could be considered as a potent source of bioactive compounds with a positive effect in health. As for the results the extracts exhibit a potent antioxidant activity, a high inhibitory power of tyrosinase and a very high affinity to in vitro inhibit the NO production, in other words a potent anti-inflammatory activity. In a near Future it is probably that B.leachii could be used by the food, cosmetic or pharmaceutical industry, as a source of bioactive molecules in favor of human’s health and quality. Also the study gives propose to the excess of B. leachii biomass found in Mediterranean Sea.