Sensores eletroquímicos à base de nanomateriais carbonáceos e catalisadores biomiméticos para determinação de tetraciclina em diferentes tipos de amostras

Pós-graduação em Química - IQ

Nanozeólitas como suportes sólidos para imobilização enzimática: Síntese, caracterização de complexos nanozeólitas/enzimas e sua aplicação como catalisadores heterogêneos para produção de biodiesel via rota etílica

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Glyceraldehyde 3-phosphate dehydrogenase-telomere association correlates with redox status in trypanosoma cruzi

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Magnetically drivable nano-bio-conjugate mimicking free curcumin redox behavior

Curcumin possesses wide-ranging anti-inflammatory and anti-cancer properties and its biological activity can be correlated to its potent antioxidant capacity. Novel maghemite (gamma-Fe3O4) nanoparticles, characterized by a diameter of about 10 nm and possessing peculiar colloidal properties and surface interactions, called Surface Active Maghemite Nanoparticles (SAMN), were superficially modified with curcumin by simple incubation, due to the presence of under-coordinated Fe(III) atoms on nanoparticle surface. The resulting curcumin-modified SAMNs (SAMN@curcumin) were characterized by transmission electron microscopy (TEM), FTIR, Mossbauer, EPR and UV-Vis spectroscopy. The redox properties of bound curcumin were tested by electrochemistry. Finally, SAMN@curcumin was studied in the presence of different electroactive substances, namely hydroquinone, NADH and ferrocyanide, in order to assess its electrochemical behavior. Moreover, SAMN@curcumin was electrochemically tested in the presence of one of the most diffuse reactive oxygen specie, such as hydrogen peroxide, demonstrating its stability. SAMN@curcumin in which curcumin is firmly bound, but still retaining its redox features represents a feasible adduct: a magnetically drivable nano-bio-conjugate mimicking free Curcumin redox behavior. The proposed nanostructured material could be exploited as magnetic drivable curcumin vehicle for biomedical applications.

Redox-active biflavonoids from Garcinia brasiliensis as inhibitors of neutrophil oxidative burst and human erythrocyte membrane damage

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Diferentes técnicas de imobilização enzimática para obtenção de catalisadores

As lipases, também chamadas de glicerol éster hidrolases, são enzimas que fazem parte do grupo das serina hidrolases, tendo como substrato, triglicerídeos. O modo de ação das lipases assemelha-se ao das esterases, realizando a hidrólise das ligações ésteres-carboxílicas de acilgliceróis, formando ácidos graxos e glicerol. Processos de bioconversão enzimática têm sido bastante utilizados na produção, transformação e valorização de matérias-primas. Avanços na tecnologia enzimática, como a imobilização de enzimas, possibilitaram a modificação das propriedades cinéticas e da estabilidade destas moléculas contribuindo com o aumento no potencial de aplicações das mesmas. O presente trabalho teve por objetivo estudar diferentes métodos de imobilização de lipases em suportes de sílica, bem como os efeitos deste procedimento, visando melhorar a funcionalidade das enzimas e o maior rendimento econômico nos processos industriais. Os métodos de imobilização escolhidos para os estudos foram: adsorção física, ligação covalente e encapsulação. O processo de imobilização de lipase em Celite (adsorção física) foi otimizado levando em conta o pH, porcentagem da concentração enzima:suporte e temperatura ótimos de atividade enzimática. Também se utilizou Celite como suporte para a imobilização de lipase por ligação covalente, onde se obteve os melhores resultados com atividade enzimática 20% a 40 ºC e eficiência de imobilização de 50%. A celite foi ativada com 3-aminopropiltrietoxisilano e glutaraldeído. Por último, foi avaliada a possibilidade de encapsulação da lipase utilizando o precursor tetraetilortossilicato (TEOS). Os resultados obtidos nesta última metodologia não se mostraram satisfatórios. Logo, com os dados obtidos, podemos dizer que uma boa manutenção da atividade catalítica depende do tipo de retenção (química ou física) e da força de interação entre a enzima e o suporte utilizado, força esta que pode, em alguns casos, causar distorções estruturais na proteína, levando a manutenção ou diminuição da atividade catalítica.

Perfil de citocinas do padrão Th1, Th2, Th17 e o estado redox de indivíduos com leishmaniose visceral pré e pós tratamento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Produção de biodiesel etílico utilizando óxidos mistos derivados de hidróxidos duplos lamelares como catalisadores

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Óxidos derivados de hidromagnesitas e hidrotalcitas modificadas como catalisadores heterogêneos na síntese de biodiesel etílico

Pós-graduação em Química - IBILCE

Influência do gênero e treinamento físico aeróbio sobre a modulação autonômica cardíaca, pressão arterial e biomarcadores de estado redox em mulheres na perimenopausa e homens

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Sínteses e caracterizações de materiais microporosos com estrutura cristalográfica mista e suas aplicações como catalisadores em reações de conversão de biomassa em produtos de química fina

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Redox Biology Center Mini-Symposium

Good morning. It's my very great pleasure to welcome you to this third annual mini-symposium in Redox Biology.

Functional and structural studies of the disulfide isomerase DsbC from the plant pathogen Xylella fastidiosa reveals a redox-dependent oligomeric modulation in vitro

Xylella fastidiosa is a Gram-negative bacterium that grows as a biofilm inside the xylem vessels of susceptible plants and causes several economically relevant crop diseases. In the present study, we report the functional and low-resolution structural characterization of the X. fastidiosa disulfide isomerase DsbC (XfDsbC). DsbC is part of the disulfide bond reduction/isomerization pathway in the bacterial periplasm and plays an important role in oxidative protein folding. In the present study, we demonstrate the presence of XfDsbC during different stages of X. fastidiosa biofilm development. XfDsbC was not detected during X. fastidiosa planktonic growth; however, after administering a sublethal copper shock, we observed an overexpression of XfDsbC that also occurred during planktonic growth. These results suggest that X. fastidiosa can use XfDsbC in vivo under oxidative stress conditions similar to those induced by copper. In addition, using dynamic light scattering and small-angle X-ray scattering, we observed that the oligomeric state of XfDsbC in vitro may be dependent on the redox environment. Under reducing conditions, XfDsbC is present as a dimer, whereas a putative tetrameric form was observed under nonreducing conditions. Taken together, our findings demonstrate the overexpression of XfDsbC during biofilm formation and provide the first structural model of a bacterial disulfide isomerase in solution. Structured digital abstract XfDsbC and XfDsbC bind by x ray scattering (View Interaction: 1, 2) XfDsbC and XfDsbC bind by molecular sieving (View interaction) XfDsbC and XfDsbC bind by comigration in non denaturing gel electrophoresis (View interaction) XfDsbC and XfDsbC bind by cross-linking study (View Interaction: 1, 2) XfDsbC and XfDsbC bind by dynamic light scattering (View Interaction: 1, 2)

Redox Control of 20S Proteasome Gating

The proteasome is the primary contributor in intracellular proteolysis. Oxidized or unstructured proteins can be degraded via a ubiquitin-and ATP-independent process by the free 20S proteasome (20SPT). The mechanism by which these proteins enter the catalytic chamber is not understood thus far, although the 20SPT gating conformation is considered to be an important barrier to allowing proteins free entrance. We have previously shown that S-glutathiolation of the 20SPT is a post-translational modification affecting the proteasomal activities. Aims: The goal of this work was to investigate the mechanism that regulates 20SPT activity, which includes the identification of the Cys residues prone to S-glutathiolation. Results: Modulation of 20SPT activity by proteasome gating is at least partially due to the S-glutathiolation of specific Cys residues. The gate was open when the 20SPT was S-glutathiolated, whereas following treatment with high concentrations of dithiothreitol, the gate was closed. S-glutathiolated 20SPT was more effective at degrading both oxidized and partially unfolded proteins than its reduced form. Only 2 out of 28 Cys were observed to be S-glutathiolated in the proteasomal alpha 5 subunit of yeast cells grown to the stationary phase in glucose-containing medium. Innovation: We demonstrate a redox post-translational regulatory mechanism controlling 20SPT activity. Conclusion: S-glutathiolation is a post-translational modification that triggers gate opening and thereby activates the proteolytic activities of free 20SPT. This process appears to be an important regulatory mechanism to intensify the removal of oxidized or unstructured proteins in stressful situations by a process independent of ubiquitination and ATP consumption. Antioxid. Redox Signal. 16, 1183-1194.

Dietary carotenoid lutein protects against DNA damage and alterations of the redox status induced by cisplatin in human derived HepG2 cells

Several epidemiological and experimental studies has been reported that lutein (LT) presents antioxidant properties. Aim of the present study was to investigate the protective effects of LT against oxidative stress and DNA damage induced by cisplatin (cDDP) in a human derived liver cell line (HepG2). Cell viability and DNA-damage was monitored by MU and comet assays. Moreover, different biochemical parameters related to redox status (glutathione, cytochrome-c and intracellular ROS) were also evaluated. A clear DNA-damage was seen with cDDP (1.0 mu M) treatment. In combination with the carotenoid, reduction of DNA damage was observed after pre- and simultaneous treatment of the cells, but not when the carotenoid was added to the cells after the exposure to cDDP. Exposure of the cells to cDDP also caused significant changes of all biochemical parameters and in co-treatment of the cells with LT, the carotenoid reverted these alterations. The results indicate that cDDP induces pronounced oxidative stress in HepG2 cells that is related to DNA damage and that the supplementation with the antioxidant LT may protect these adverse effects caused by the exposure of the cells to platinum compound, which can be a good predict for chemoprevention. (C) 2011 Elsevier Ltd. All rights reserved.