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排序方式: 共有1419条查询结果,搜索用时 46 毫秒
991.
Stefania-Felicia Barbuceanu Diana Carolina Ilies Gabriel Saramet Valentina Uivarosi Constantin Draghici Valeria Radulescu 《International journal of molecular sciences》2014,15(6):10908-10925
In the present investigation, new hydrazinecarbothioamides 4–6 were synthesized by reaction of 4-(4-X-phenylsulfonyl)benzoic acids hydrazides (X= H, Cl, Br) 1–3 with 2,4-difluorophenyl isothiocyanate and further these were treated with sodium hydroxide to obtain 1,2,4-triazole-3-thione derivatives 7–9. The reaction of 7–9 with α-halogenated ketones, in basic media, afforded new S-alkylated derivatives 10–15. The structures of the synthesized compounds have been established on the basis of 1H-NMR, 13C-NMR, IR, mass spectral studies and elemental analysis. The antioxidant activity of all compounds has been screened. Hydrazinecarbothioamides 4–6 showed excellent antioxidant activity and 1,2,4-triazole-3-thiones 7–9 showed good antioxidant activity using the DPPH method. 相似文献
992.
993.
Roberto Valenzuela Jean Franco Castro Carolina Parra Jaime Baeza Nelson Durán Juanita Freer 《Journal of Experimental Nanoscience》2014,9(2):177-185
β-Glucosidase from Trichoderma reesei was immobilised on synthetic superparamagnetic magnetite (Fe3O4) nanoparticles with a mean diameter of 10?nm and were used to supplement cellulase in the enzymatic hydrolysis of three substrates: wheat straw pretreated by steam explosion, Eucalyptus globulus pretreated by hydrothermolysis and E. globulus pretreated by hydrothermolysis followed by alkaline extraction. The hydrolysis yields for each pretreated material, using immobilised β-glucosidase (I-βG) and free cellulase, were 76.1%, 83.6% and 75.6%, respectively, and resulted in an improved hydrolysis yields compared with only cellulase. These yields were at most 10% lower than yields reached with free enzymes. The (I-βG) was magnetically recovered and successfully reused twice. The differences in the hydrolysis yields were not significant (p?>?0.05) in the case of steam-exploded wheat straw and E. globulus pretreated by hydrothermolysis followed by alkaline extraction. The immobilisation of enzymes provides an opportunity to reduce the costs of enzymes in the bioethanol production process. 相似文献
994.
Genome Mining of Streptomyces sp. Tü 6176: Characterization of the Nataxazole Biosynthesis Pathway
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Carolina Cano‐Prieto Dr. Raúl García‐Salcedo Dr. Marina Sánchez‐Hidalgo Prof. Alfredo F. Braña Prof. Hans‐Peter Fiedler Prof. Carmen Méndez Prof. José A. Salas Dr. Carlos Olano 《Chembiochem : a European journal of chemical biology》2015,16(10):1461-1473
Streptomyces sp. Tü 6176 produces the cytotoxic benzoxazole nataxazole. Bioinformatic analysis of the genome of this organism predicts the presence of 38 putative secondary‐metabolite biosynthesis gene clusters, including those involved in the biosynthesis of AJI9561 and its derivative nataxazole, the antibiotic hygromycin B, and ionophores enterobactin and coelibactin. The nataxazole biosynthesis gene cluster was identified and characterized: it lacks the O‐methyltransferase gene required to convert AJI9561 into nataxazole. This O‐methyltransferase activity might act as a resistance mechanism, as AJI9561 shows antibiotic activity whereas nataxazole is inactive. Moreover, heterologous expression of the nataxazole biosynthesis gene cluster in S. lividans JT46 resulted in the production of AJI9561. Nataxazole biosynthesis requires the shikimate pathway to generate 3‐hydroxyanthranilate and an iterative type I PKS to generate 6‐methylsalicylate. Production of nataxazole was improved up to fourfold by disrupting one regulatory gene in the cluster. An additional benzoxazole, 5‐hydroxynataxazole is produced by Streptomyces sp. Tü 6176. 5‐Hydroxynataxazole derives from nataxazole by the activity of an as yet unidentified oxygenase; this implies cross‐talk between the nataxazole biosynthesis pathway and an unknown pathway. 相似文献
995.
Jennifer S. Coelho Alyssa Idler Carolina O.C. Werle Anita Jansen 《Food quality and preference》2011,22(8):780-784
Food-scented products are widely available, yet it is unclear whether they influence eating behavior. Food-related cues can increase intake; therefore, it was anticipated that conscious exposure to food-scented products (e.g., body lotion) could also influence consumption. Female participants (n = 58) were randomly assigned to an exposure condition (labeled chocolate lotion, unlabeled chocolate lotion, or unscented lotion), and their subsequent intake of chocolate-chip cookies was measured. A significant effect of condition on intake emerged. Those who knew that they were evaluating a chocolate-scented lotion ate more than did those exposed to the same (unlabeled) lotion, suggesting that conscious exposure to chocolate-related products may increase food intake. 相似文献
996.
Relating safety, productivity and company type for motor-manual logging operations in the Italian Alps 总被引:1,自引:0,他引:1
Niccolò Brachetti Montorselli Carolina Lombardini Natascia Magagnotti Enrico Marchi Francesco Neri Gianni Picchi Raffaele Spinelli 《Accident; analysis and prevention》2010,42(6):2013-2017
The study compared the performance of four different logging crews with respect to productivity, organization and safety. To this purpose, the authors developed a data collection method capable of providing a quantitative analysis of risk-taking behavior. Four crews were tested under the same working conditions, representative of close-to-nature alpine forestry. Motor-manual working methods were applied, since these methods are still prevalent in the specific study area, despite the growing popularity of mechanical processors. Crews from public companies showed a significantly lower frequency of risk-taking behavior. The best safety performance was offered by the only (public) crew that had been administered formal safety training. The study seems to deny the common prejudice that safety practice is inversely proportional to productivity. Instead, productivity is increased by introducing more efficient working methods and equipment. The quantitative analysis of risk-taking behavior developed in this study can be applied to a number of industrial fields besides forestry. Characterizing risk-taking behavior for a given case may eventually lead to the development of custom-made training programmes, which may address problem areas while avoiding that the message is weakened by the inclusion of redundant information. In the specific case of logging crews in the central Alps, the study suggests that current training courses may be weak on ergonomics, and advocates a staged training programme, focusing first on accident reduction and then expanding to the prevention of chronic illness. 相似文献
997.
998.
Although the joining of blunt ends in yeast by non‐homologous end joining (NHEJ) is reported to be inefficient in comparison to cohesive‐end joining (Boulton and Jackson, 1996 ), we find that efficiency varies greatly, depending on strain, growth phase and sequence. In particular, the levels of efficiency of recircularization of a plasmid linearized by non‐cohesive cleavage is augmented to that of cohesive end joining if the cleavage cut site is flanked by sequences present in the genome. We call this enhancement ‘homology‐assisted end joining’ (HAEJ), which depends on components of the NHEJ repair pathway and, in some cases, on components of the homologous recombination (HR) pathway and on Htl1 a component of the remodels structure of chromatin (RSC) complex. The homologous genome sequences are not used as templates for repair DNA synthesis, but may facilitate end‐to‐end collision and ligation by providing a track for guided diffusion. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
999.
Carolina Farah Gloria Levicán Michael Ibba Omar Orellana 《International journal of molecular sciences》2014,15(12):23011-23023
Glutamyl-tRNA (Glu-tRNAGlu) is the common substrate for both protein translation and heme biosynthesis via the C5 pathway. Under normal conditions, an adequate supply of this aminoacyl-tRNA is available to both pathways. However, under certain circumstances, Glu-tRNAGlu can become scarce, resulting in competition between the two pathways for this aminoacyl-tRNA. In Acidithiobacillus ferrooxidans, glutamyl-tRNA synthetase 1 (GluRS1) is the main enzyme that synthesizes Glu-tRNAGlu. Previous studies have shown that GluRS1 is inactivated in vitro by hydrogen peroxide (H2O2). This raises the question as to whether H2O2 negatively affects in vivo GluRS1 activity in A. ferrooxidans and whether Glu-tRNAGlu distribution between the heme and protein biosynthesis processes may be affected by these conditions. To address this issue, we measured GluRS1 activity. We determined that GluRS1 is inactivated when cells are exposed to H2O2, with a concomitant reduction in intracellular heme level. The effects of H2O2 on the activity of purified glutamyl-tRNA reductase (GluTR), the key enzyme for heme biosynthesis, and on the elongation factor Tu (EF-Tu) were also measured. While exposing purified GluTR, the first enzyme of heme biosynthesis, to H2O2 resulted in its inactivation, the binding of glutamyl-tRNA to EF-Tu was not affected. Taken together, these data suggest that in A. ferrooxidans, the flow of glutamyl-tRNA is diverted from heme biosynthesis towards protein synthesis under oxidative stress conditions. 相似文献
1000.
Carla Andrea Calderon Rosas Matthias Franzreb Fernando Valenzuela Wolfgang H. Höll 《Reactive and Functional Polymers》2010,70(8):516-520
Manganese dioxide (δ-MnO2) with magnetic properties has been synthesized by precipitation of MnO2 in the presence of magnetite. The resulting material has a particle size distribution between 0.5 and 5 μm. Magnetization of the material is in the order of magnitude of that of magnetite. Therefore a solid–liquid separation by means of moderate magnetic fields is possible. Due to the properties of δ-MnO2 the point of zero charge of the surface is about 2.5. Therefore, the adsorbent is almost exclusively a cation exchanger although sorption of oxoanions is also possible. Sorption experiment with Cd2+, Ni2+, and Pb2+ ions revealed a preferred sorption. Alkaline earth ions such as Ca2+ affect the uptake only at high concentrations. Because of the small particles and the respective large specific surface, sorption is fast. 相似文献