937 resultados para CYSTEINE RESIDUES
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Snake venom metalloproteases (SVMPs) embody zinc-dependent multidomain enzymes responsible for a relevant pathophysiology in envenomation. including local and systemic hemorrhage. The molecular features responsible for hemorrhagic potency of SVMPs have been associated with their multidomains structures which can target these proteins them to several receptors of different tissues and cellular types. BjussuMP-I. a SVMP isolated from the Bothrops jararacussu venom, has been characterized as a P-III hemorrhagic metalloprotease. The complete cDNA sequence of BjussuMP-I with 1641bp encodes open reading frames of 547 amino acid residues, which conserve the common domains of P-III high molecular weight hemorrhagic metalloproteases: (i) pre-pro-peptide, (ii) metalloprotease, (iii) disintegrin-like and (iv) rich cysteine domain. BjussuMP-I induced lyses in fibrin clots and inhibited collagen- and ADP-induced platelet aggregation. We are reporting, for the first time, the primary structure of an RGD-P-III class snake venom metalloprotease. A phylogenetic analysis of the BjussuMP-1 metalloprotease/catalytic domain was performed to get new insights into the molecular evolution of the metalloproteases. A theoretical molecular model of this domain was built through folding recognition (threading) techniques and refined by molecular dynamics simulation. Then, the final BjussuMP-I catalytic domain model was compared to other SVMPs and Reprolysin family proteins in order to identify eventual structural differences, which could help to understand the biochemical activities of these enzymes. The presence of large hydrophobic areas and some conserved surface charge-positive residues were identified as important features of the SVMPs and other metalloproteases. (C) 2006 Elsevier B.V. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The Brazilian sugarcane industry shows a great amount of generated sludge which should be utilized adequately. Two sludge samples, aerobic and anaerobic, were collected. Both were evaluated by thermogravimetry and differential thermal analysis (DTA) as well as X-ray power diffraction. These compounds show variations of mass between 30 and 140 A degrees C due to the dehydration stage. The DTA curves show that the compounds have an exothermic reaction between 450 and 550 A degrees C, which indicates that this can be used as an energy source. Details concerning the kinetic parameters of the dehydration and thermal decomposition have also been described here. The kinetic study of these stages was evaluated in open crucibles under nitrogen atmosphere. The obtained data were evaluated with the isoconversional kinetic method. The results show that different activation energies were obtained for thermal decomposition.
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The number of the cities with canalized water and sewage treatment stations has increased lately and consequently having in mind the great concern on environment preservation and the quality of the water used by society. However, these stations are nowadays causing another kind of problem: a huge quantity of sludge as residue. Due to the implication of the residue on the environment and, consequently, to human life quality, performing of an accurate investigation about the components of such sludge, as well as the thermal stability of this residue in the environment become necessary. This paper presents a study on sludge from water and sewage treatment station, as well as the thermal characterization of residue. Such study was performed through FTIR, atomic absorption, thermoanalytical (TG/DTG, DTA) techniques, that made it possible to observe that the main components of the sludge are clay, carbonates and organic substance, presenting a low rate of metals and a unique thermal behavior since the sludge from the treatment station has a higher thermal stability.
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Urban solid residues are constituted of food remaining, grass leaves, fruit peelings, paper, cardboard, rubber, plastic, etc. The organic fraction formed represents about 50% during the decomposition yields biogas and leachate, which are sources of pollution. Residue samples were collected from the landfill in different and cells from several ages and the corresponding leachate, both after treatments, were submitted to thermal analysis. Kinetic parameters were determined using Flynn-Wall-Ozawa method. The linear relation between the two kinetic parameters (ln A and E) was verified for organic residue urban's samples, but not for leachate's sample. The occurred difference can be attributed to the constituents present in leachate.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Herbicidas tais como trifluralina, simazina, atrazina, metribuzina e metolaclor são usados na agricultura brasileira. A eficiência de um método em pequena escala para a determinação destes herbicidas e dois produtos de degradação em amostras de solo foi avaliada. Os compostos foram extraídos das amostras de solo (5 g) com 20 ml de acetato de etila em agitador mecânico por 50 min. Após a extração, o sobrenadante foi filtrado em sulfato de sódio anidro, concentrado e analisado por cromatografia a gás de alta resolução com detector termiônico específico. Valores médios de recuperação obtidos de amostras de solo fortificadas em três níveis diferentes variaram de 81 a 115 % com valores de desvio padrão relativo entre 1,2 e 12,7 %. Os limites de detecção do método variaram de 0,01 a 0,06 mg kg-1. A metodologia foi aplicada a amostras de solo de fazendas localizadas próximas à cidade de Araraquara, estado de São Paulo, Brasil.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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O aumento da produção hortícola em cultivo protegido necessita de estudos mais detalhados acerca da ocorrência de resíduos de agrotóxicos, devido às condições ambientais peculiares nesse sistema, no qual pragas de pouca importância no campo assumem relevância. Avaliou-se os resíduos dos inseticidas acefato e de seu metabólito metamidofós em tomate sob cultivo protegido e em campo. Os tratamentos aplicados foram: (a) testemunha; (b) uma aplicação de 75 g i.a. acefato.100 L-1 de água; (c) uma aplicação com 150 g i.a.100 L-1 de água; (d) quatro aplicações na dosagem de 75 g i.a.100 L-1 de água. As amostras foram tomadas a (-1), zero, 1, 3, 7, 14 e 21 dias após a última ou única aplicação. A determinação quantitativa foi feita por técnica de cromatografia em fase gasosa, usando-se detector fotométrico de chama. Os resíduos de acefato e de metamidofós nos frutos de cultivo protegido e de campo, sempre estiveram abaixo dos respectivos limites máximos de resíduos (LMRs) em todo o período de colheita das amostras. Ainda, o metabolismo de acefato a metamidofós foi muito baixo nos frutos, particularmente importante nas folhas, mas não foi bem caracterizado no solo. Os resíduos de acefato foram maiores no cultivo protegido do que no campo, especialmente em folhas e no solo, sendo também estáveis e persistentes, em geral até a amostragem de 7 dias após a aplicação.