127 resultados para Molybdenum Enzyme


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Recently, there is an interest in technologies that favour the use of coproducts for animal nutrition. The effect of adding two enzyme mixtures in diets for dogs formulated with wheat bran (WB) was evaluated. Two foods with similar compositions were formulated: negative control (NC; without WB) and test diet (25% of WB). The test diet was divided into four treatments: without enzyme (positive control), enzyme mixture 1 (ENZ1; added before extrusion β-glucanase, xylanase, cellulase, glucoamylase, phytase); enzyme mixture 2 (ENZ2; added before extrusion the ENZ1 more α-amylase); enzyme mixture 2 added after the extrusion (ENZ2ex). ENZ1 and ENZ2 were used to evaluate the enzyme effect on extruder pre-conditioner (processing additive) and ENZ2ex to evaluate the effect of enzyme supplementation for the animal. Digestibility was measured through total collection of faeces and urine. The experiment followed a randomized block design with five treatments (diets) and six dogs per diet, totalling 30 dogs (7.0 ± 1.2 years old and 11.0 ± 2.2 kg of body weight). Data were submitted to analysis of variance and means compared by Tukey's test and orthogonal contrasts (p < 0.05). Reducing sugars showed an important reduction after extrusion, suggesting the formation of carbohydrate complexes. The apparent total tract digestibility (ATTD) of dry matter, organic matter, crude protein, acid-hydrolysed fat and energy was higher in NC than in diets with WB (p < 0.001), without effects of enzyme additions. WB diets resulted in higher faecal production and concentration of short-chain fatty acids (SCFA) and reduced pH and ammonia concentration (p < 0.01), with no effect of enzyme addition. The enzyme addition did not result in improved digestibility of a diet high in non-starch polysaccharides; however, only ATTD was measured and nutrient fermentation in the large intestine may have interfered with the results obtained. WB modified fermentation product formation in the colon of dogs. © 2013 Blackwell Verlag GmbH.

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This work describes the characterization of the [Mn2 IV,IVO2(terpy)2(H2O)2]4+ complex in aqueous solution by UV-vis spectrophotometry, cyclic voltammetry, and linear sweep voltammetry with a rotating disk electrode. The pH effect, potential scan rate, effect of perfluorosulfonate polymer, and anion of supporting electrode on the electrochemical behavior of the modified electrode for better performance were investigated. The potential peak of the modified electrode was linearly dependent upon the ratio [ionic charge]/[ionic radius]. The modified electrode exerted an electrocatalytic effect on dopamine oxidation in aqueous solution with a decrease in the overpotential compared with the unmodified glassy carbon electrode. This way, the modified electrode showed an enzymatic biomimicking behavior. Tafel plot analyses were used to elucidate the kinetics and mechanism of dopamine oxidation. © 2013 Springer Science+Business Media New York.

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A simplified procedure for the preparation of immobilized beta-amylase using non-purified extract from fresh sweet potato tubers is established in this paper, using differently activated agarose supports. Beta-amylase glutaraldehyde derivative was the preparation with best features, presenting improved temperature and pH stability and activity. The possibility of reusing the amylase was also shown, when this immobilized enzyme was fully active for five cycles of use. However, immobilization decreased enzyme activity to around 15%. This seems to be mainly due to diffusion limitations of the starch inside the pores of the biocatalyst particles. A fifteen-fold increase in the Km was noticed, while the decrease of Vmax was only 30% (10.1 U mg-1 protein and 7.03 U mg-1 protein for free and immobilized preparations, respectively). © 2013 Elsevier Ltd.

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The increased production of urban sewage sludge requires alternative methods for final disposal. A very promising choice is the use of sewage sludge as a fertilizer in agriculture, since it is rich in organic matter, macro and micronutrients. However, urban sewage sludge may contain toxic substances that may cause deleterious effects on the biota, water and soil, and consequently on humans. There is a lack of studies evaluating how safe the consumption of food cultivated in soils containing urban sewage sludge is. Thus, the aim of this paper was to evaluate biochemical and redox parameters in rats fed with corn produced in a soil treated with urban sewage sludge for a long term. For these experiments, maize plants were grown in soil amended with sewage sludge (rates of 5, 10 and 20. t/ha) or not (control). Four different diets were prepared with the corn grains produced in the field experiment, and rats were fed with these diets for 1, 2, 4, 8 and 12 weeks. Biochemical parameters (glucose, total cholesterol and fractions, triglycerides, aspartate aminotransferase and alanine aminotransferase) as well the redox state biomarkers such as reduced glutathione (GSH), malondialdehyde (MDA), catalase, glutathione peroxidase and butyrylcholinesterase (BuChE) were assessed. Our results show no differences in the biomarkers over 1 or 2 weeks. However, at 4 weeks BuChE activity was inhibited in rats fed with corn grown in soil amended with sewage sludge (5, 10 and 20. t/ha), while MDA levels increased. Furthermore, prolonged exposure to corn cultivated in the highest amount per hectare of sewage sludge (8 and 12 weeks) was associated with an increase in MDA levels and a decrease in GSH levels, respectively. Our findings add new evidence of the risks of consuming food grown with urban sewage sludge. However, considering that the amount and type of toxic substances present in urban sewage sludge varies considerably among different sampling areas, further studies are needed to evaluate sludge samples collected from different sources and/or undergoing different types of treatment. © 2013 Elsevier Inc.

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Microbial enzymes have been used for various biotechnological applications; however, enzyme stabilization remains a challenge for industries and needs to be considered. This study describes the effects of spray-drying conditions on the activity and stability of β-fructofuranosidase from Fusarium graminearum. The extracellular enzyme β-fructofuranosidase was spray dried in the presence of stabilizers, including starch (Capsul) (SC), microcrystalline cellulose (MC), trehalose (TR), lactose (LC) and β-cyclodextrin (CD). In the presence of TR (2% w/v), the enzymatic activity was fully retained. After 1 year of storage, 74% of the enzymatic activity was maintained with the CD stabilizer (10% w/v). The residual activity was maintained as high as 80% for 1 h at 70°C when MC, SC and CD (5% w/v) stabilizers were used. Spray drying with carbohydrates was effective in stabilizing the F. graminearum β-fructofuranosidase, improved enzymatic properties compared to the soluble enzyme and demonstrated a potential use in future biotechnology applications. © 2013 Informa UK Ltd. All rights reserved.

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Thermophilic fungus Thermoascus aurantiacus (CBMAI 756) on solid-state fermentation using corncob as a nutrient source produces an enzyme pool with the potential to be used in bread making. In this paper, the use of this enzyme cocktail as a wheat bread improver was reported. Both products released by flour arabinoxylan degradation and bread quality were investigated. The main product released through enzyme activity after prolonged incubation was xylose indicating the presence of xylanase; however, a small amount of xylobiose and arabinose also confirmed the presence of xylosidase and α-L- arabinofuranosidase, respectively. Enzyme mixture in vitro mainly attacked water-unextractable arabinoxylan contributing to beneficial effect in bread making. The use of an optimal enzyme concentration (35 U xylanase/100 g of flour) increased specific volume (22%), reduced crumb firmness (25%), and reduced amylopectin retrogradation (17%) during bread storage. In conclusion, the enzyme cocktail produced by T. aurantiacus CBMAI 756 can improve wheat bread quality. © 2013 Elsevier Ltd.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The properties of a previously unknown enzyme, denominated cyclodextrin glycosyltransferase, produced from Bacillus lehensis, were evaluated using affinity chromatography for protein purification. Enzyme characteristics (optimum pH and temperature; pH and temperature stability), the influence of substances on the enzyme activity, enzyme kinetics, and cyclodextrin production were analysed. Cyclodextrin glycosyltransferase was purified up to 320.74-fold by affinity chromatography using beta-cyclodextrin as the binder and it exhibited 8.71% activity recovery. This enzyme is a monomer with a molecular weight of 81.27 kDa, as estimated by SDS-PAGE. Optimum temperature and pH for cydodextrin glycosyltransferase were 55 degrees C and 8.0, respectively. The Michaelis-Menten constant was 8.62 g/l during maximum velocity of 0.858 g/l.h.

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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)