Eficiência agronômica da ureia estabilizada com inibidores de urease e nitrificação na cultura do milho

Nitrogen (N) is the most required nutrient for corn plants and, in order to supply this demand in highly productive crops, mineral fertilizers are used, especially urea. The disadvantage of urea is the loss of N-NH3 to atmosphere. To reverse this situation, some technologies have been developed, such as nitrification and urease inhibitors, which are used as additives to urea. This work aimed at evaluating the agronomic efficiency of urea stabilized with urease and nitrification inhibitors applied to cover the 2013/2014 corn crop. We evaluated 11 nitrogen fertilizer applied in coverage: urea + PA (41.6% N, 3% Cu); urea + PA (41.6% N, 1.5% Cu); urea + PA (41.6% N, 3% Zn); urea + PA (41.6% N, 1.5% Zn); urea + PA (41.6% N, 0.34% Cu, 0.94% B); urea + PA (41.6% N, 0.25% Cu, 0.68% B); urea + PA (41.6% N); urea (44.3% N, 0.15% Cu, 0.4% B); urea (43% N, 0.1% Cu, 0.3% B, 0.05% Mo); pearled urea (46% N); urea + 0,8% DMPP (45% N) and the control, which did not receive nitrogen topdressing. The evaluations were: Nitrogen losses through volatilization, content and accumulation of N, boron (B), copper (Cu) and zinc (Zn) to the dry matter of aerial parts, grains, and in straw and grain productivity. Fertilizers stabilized with urease and nitrification inhibitors did not reduce the volatilization of ammonia volatilization, when compared to pearled urea. Urea with 0.8% of DMPP nitrification inhibitor (3,4-dimethylpyrazole phosphate) provided higher loss by volatilization, lower productivity and agronomic efficiency compared to pearled urea. The coating of urea with Cu, B and Zn did not increase the accumulation of these nutrients in grains and MSPA plants. The use of fertilizers stabilized and coated with micronutrients did not increase the productivity and agronomic efficiency compared to conventional urea.

Compostos antibacterianos e/ou antiprotozoários derivados do nitroimidazol apresentando atividade inibidora de urease, processo de preparação destes compostos e uso em composições farmacêuticas e medicamentos

No presente pedido são descritos compostos derivados nitroimidazólicos com atividade antibacteriana e/ou antiprotozoária, os quais são potentes inibidores da urease. São também descritos o processo de obtenção destes compostos, e o uso destes em composições farmacêuticas e medicamentos.

Helibacter pylori: preaparação de Lapdesf-IUNI e ensaio de inibição de urease (IC50) de derivados de tiouréia e guanidínicos

O presente trabalho de conclusão de curso visou à otimização e preparação da síntese de Lapdesf-IUNI e avaliação do potencial de inibição de urease de três compostos previamente sintetizados, direcionados especificamente para o tratamento de infecções por Helicobacter pylori, bactéria mundialmente reconhecida como uma das principais causadoras de infecções no mundo, responsável pelos casos de infecções gástricas, como gastrites crônicas, úlceras (gástricas e duodenais) e carcinomas. Lapdesf-IUNI é um composto derivado de metronidazol, com atividade potencialmente inibidora de urease, enzima presente neste microrganismo e essencial a sua sobrevivência no ambiente gástrico. O produto foi obtido, porém com baixo rendimento, por isso sua metodologia ainda necessita ser aperfeiçoada, para que, em seguida este composto possa ser testado. Outros três compostos, um derivado de tiouréia e dois derivados guanidínicos, com potencial atividade inibidora de urease, T-6, R-17 e R-21, sintetizados pela equipe do Prof. Eduardo Perez, foram avaliados com relação a sua atividade inibidora frente à enzima urease e IC50, apresentando bons resultados, que permitem a continuidade dos estudos, comparando inclusive com fármacos utilizados nos protocolos de tratamento padrões para o tratamento das infecções causadas por H. pylori

Determinação da temperatura para inativação da urease em amostras de casca e farelo de soja

s not degraded in the rumen but destroy ureasis. Soybean meal is one of the protein ingredients commonly used in formulations of animal feeds. In the diets of monogastric bran has high protein content provided by a greater separation of soybean hulls. For the ruminant protein value of the meal is lower with the inclusion of soybean hulls to reduce the level of protein. With the increased consumption of meal high protein, due to increases in production of pigs and poultry in recent years, increasing the availability of soybean hulls on the market, this is because soybean hulls is little understood in the feeding of monogastric . In this context, the main objective of this study was to determine the times and temperatures needed to ensure the effective inactivation of ureasis present in the bran and soybean hulls. According to the assessments, to make the determination of temperatures and times required for the inactivation of ureasis present in the bran and soybean hulls are 170 º C and 25 minutes for soybean meal and 140 ° C 10 minutes for soybean hulls, respectively

Amperometric urea biosensors based on the entrapment of urease in polypyrrole films

Urease (Urs) was immobilized in electrochemically prepared polypyrrole (PPy) and the resulting films were characterized by cyclic voltammetry, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and ultraviolet visible spectroscopy (UV-VIS). The enzymatic activity of Urs entrapped in the PPy matrix was confirmed by the catalytic conversion of urea into carbon dioxide and ammonia, when urea was detected amperometrically at different concentrations in standard samples and commercial fertilizers. The PPy/Urs biosensors exhibited selectivity, a relatively high efficiency at urea concentrations below 3.0 mmol L-1, and a sensitivity to urea of 2.41 mu A cm(-2) mmol(-1) L (C) 2011 Elsevier Ltd. All rights reserved.

Carbon isotope fractionation during calcium carbonate precipitation induced by urease-catalysed hydrolysis of urea

Stable carbon isotopic fractionation during calcium carbonate precipitation induced by urease-catalysed hydrolysis of urea was experimentally investigated in artificial water at a constant temperature of 30 degrees C. Carbon isotope fractionation during urea hydrolysis follows a Rayleigh distillation trend characterized by a C-13-enrichment factor of -20 to -22 parts per thousand. CaCO3 precipitate is up to 17.9 parts per thousand C-13-depleted relative to the urea substrate (-48.9 +/- 0.07 parts per thousand). Initial CaCO3 precipitate forms close to isotopic equilibrium with dissolved inorganic carbon. Subsequent precipitation occurs at -2 to -3 parts per thousand offset from isotopic equilibrium, suggesting that the initial delta C-13 value of CaCO3 is reset through dissolution followed by reprecipitation with urease molecules playing a role in offsetting the delta C-13 value of CaCO3 from isotopic equilibrium. Potentially, this isotopic systematics may provide a tool for the diagnosis of ureolytically-formed carbonate cements used as sealing agent. Moreover, it may serve as a basis to develop a carbon isotope tool for the quantification of ureolytically-induced CO2 sequestration. Finally, it suggests carbon isotope disequilibrium as a hallmark of past enzymatic activity in ancient microbial carbonate formation. (C) 2012 Elsevier B.V. All rights reserved.

Molecular interactions: metal ions and protein chaperones in the urease system from Helicobacter pylori

Although nickel is a toxic metal for living organisms in its soluble form, its importance in many biological processes recently emerged. In this view, the investigation of the nickel-dependent enzymes urease and [NiFe]-hydrogenase, especially the mechanism of nickel insertion into their active sites, represent two intriguing case studies to understand other analogous systems and therefore to lead to a comprehension of the nickel trafficking inside the cell. Moreover, these two enzymes have been demonstrated to ensure survival and colonization of the human pathogen H. pylori, the only known microorganism able to proliferate in the gastric niche. The right nickel delivering into the urease active site requires the presence of at least four accessory proteins, UreD, UreE, UreF and UreG. Similarly, analogous process is principally mediated by HypA and HypB proteins in the [NiFe]-hydrogenase system. Indeed, HpHypA and HpHypB also have been proposed to act in the activation of the urease enzyme from H. pylori, probably mobilizing nickel ions from HpHypA to the HpUreE-HpUreG complex. A complete comprehension of the interaction mechanism between the accessory proteins and the crosstalk between urease and hydrogenase accessory systems requires the determination of the role of each protein chaperone that strictly depends on their structural and biochemical properties. The availability of HpUreE, HpUreG and HpHypA proteins in a pure form is a pre-requisite to perform all the subsequent protein characterizations, thus their purification was the first aim of this work. Subsequently, the structural and biochemical properties of HpUreE were investigated using multi-angle and quasi-elastic light scattering, as well as NMR and circular dichroism spectroscopy. The thermodynamic parameters of Ni2+ and Zn2+ binding to HpUreE were principally established using isothermal titration calorimetry and the importance of key histidine residues in the process of binding metal ions was studied using site-directed mutagenesis. The molecular details of the HpUreE-HpUreG and HpUreE-HpHypA protein-protein assemblies were also elucidated. The interaction between HpUreE and HpUreG was investigated using ITC and NMR spectroscopy, and the influence of Ni2+ and Zn2+ metal ions on the stabilization of this association was established using native gel electrophoresis, light scattering and thermal denaturation scanning followed by CD spectroscopy. Preliminary HpUreE-HpHypA interaction studies were conducted using ITC. Finally, the possible structural architectures of the two protein-protein assemblies were rationalized using homology modeling and docking computational approaches. All the obtained data were interpreted in order to achieve a more exhaustive picture of the urease activation process, and the correlation with the accessory system of the hydrogenase enzyme, considering the specific role and activity of the involved protein players. A possible function for Zn2+ in the chaperone network involved in Ni2+ trafficking and urease activation is also envisaged.

Structural and biochemical studies of Sporosarcina pasteurii UreE: a nickel-chaperone involved in the urease activation process

Urease is a nickel-dependent enzyme that catalyzes hydrolysis of urea in the last step of organic nitrogen mineralization. Its active site contains a dinuclear center for Ni(II) ions that must be inserted into the apo-enzyme through the action of four accessory proteins (UreD, UreE, UreF, UreG) leading to activation of urease. UreE, acting as a metallo-chaperone, delivers Ni(II) to the preformed complex of apo-urease-UreDFG and has the capability to enhance the GTPase activity of UreG. This study, focused on characterization of UreE from Sporosarcina pasteurii (SpUreE), represents a piece of information on the structure/mobility-function relationships that control nickel binding by SpUreE and its interaction with SpUreG. A calorimetric analysis revealed the occurrence of a binding event between these proteins with positive cooperativity and a stoichiometry consistent with the formation of the (UreE)2-(UreG)2 hetero-oligomer complex. Chemical Shift Perturbations induced by the protein-protein interaction were analyzed using high-resolution NMR spectroscopy, which allowed to characterize the molecular details of the protein surface of SpUreE involved in the complex formation with SpUreG. Moreover, backbone dynamic properties of SpUreE, determined using 15N relaxation analysis, revealed a general mobility in the nanoseconds time-scale, with the fastest motions observed at the C-termini. The latter analysis made it possible for the first time to characterize of the C-terminal portions, known to contain key residues for metal ion binding, that were not observed in the crystal structure of UreE because of disorder. The residues belonging to this portion of SpUreE feature large CSPs upon addition of SpUreG, showing that their chemical environment is directly affected by protein-protein interaction. Metal ion selectivity and affinity of SpUreE for cognate Ni(II) and non cognate Zn(II) metal ions were determined, and the ability of the protein to select Ni(II) over Zn(II), in consistency with the proposed role in Ni(II) cations transport, was established.

Soil moisture content determines the effect of the urease inhibitor NBPT on N2O emissions

Among the mitigation strategies to prevent nitrogen (N) losses from ureic fertilizers, urease inhibitors (UIs) have been demonstrated to promote high N use efficiency by reducing ammonia (NH3) volatilization. In the last few years, some field experiments have also shown its effectiveness in reducing nitrous oxide (N2O) losses from fertilized soils under conditions of low soil moisture. An incubation experiment was carried out with the aim of assessing the main biotic mechanisms behind N2O emissions once that the UIs N-(n-butyl) thiophosphoric triamid (NBPT) and phenil phosphorodiamidate (PPDA) were applied with Urea (U) under different soil moisture conditions (40, 60 and 80 % water-filled pore space, WFPS). In the same study we tried to analyze to what extent soil WFPS regulates the effect of these inhibitors on N2O emissions. The use of PPDA in our study allowed us to compare the effect of NBPT with that of another commercially available urease inhibitor, aiming to see if the results were inhibitor-specific or not. Based on the results from this experiment, a WFPS (i.e. 60 %) was chosen for a second study (i.e. mesocosm experiment) aiming to assess the efficiency of the UIs to indirectly affect N2O emissions through influencing the pool of soil mineral N. The N2O emissions at 40 % WFPS were almost negligible, being significantly lower from all fertilized treatments than that produced at 60 and 80 % WFPS. When compared to U alone, NBPT+U reduced the N2O emissions at 60 % WFPS but had no effect at 80 % WFPS. The application of PPDA significantly increased the emissions with respect to U at 80 % WFPS whereas no significant effect was found at 60 %. At 80 % WFPS, denitrification was the main source of N2O emissions for all treatments. In the mesocosm study, the application of NBPT+U was an effective strategy to reduce N2O emissions (75 % reduction compared to U alone), due to a lower soil ammonium (NH4 +) content induced by the inhibitor. These results suggest that adequate management of the UI NBPT could provide, under certain soil conditions, an opportunity for mitigation of N2O emissions from fertilized soils.

The urease locus of Mycobacterium tuberculosis and its utilization for the demonstration of allelic exchange in Mycobacterium bovis bacillus Calmette-Guérin.

The ureABC genes of Mycobacterium tuberculosis were cloned. By using a set of degenerate primers corresponding to a conserved region of the urease enzyme (EC 3.5.1.5), a fragment of the expected size was amplified by PCR and was used to screen a M. tuberculosis cosmid library. Three open reading frames with extensive similarity to the urease genes from other organisms were found. The locus was mapped on the chromosome, using an ordered M. tuberculosis cosmid library. A suicide vector containing a ureC gene disrupted by a kanamycin marker (aph) was used to construct a urease-negative Mycobacterium bovis bacillus Calmette-Guérin mutant by allelic exchange involving replacement of the ureC gene with the aph::ureC construct. To our knowledge, allelic exchange has not been reported previously in the slow-growing mycobacteria. Homologous recombination will be an invaluable genetic tool for deciphering the mechanisms of tuberculosis pathogenesis, a disease that causes 3 x 10(6) deaths a year worldwide.

Nanoassembly of biocompatible microcapsules for urease encapsulation and their use as biomimetic reactors

Biocompatible polypeptide capsules with high enzyme loading and activity prepared by templating mesoporous silica spheres were used as biomimetic reactors for performing CaCO3 synthesis exclusively inside the capsule interior via urease-catalyzed urea hydrolysis.

Efeito da co-inoculação de microorganismos solubilizadores de fósforo, fungos micorrízicos e Azospirillum sobre a atividade enzimática da urease e arginase no cultivo do milheto.

2016

Captação de CO2 por plantas de milho adubadas com ureia revestida com inibidores de urease.

2016

Alterações das enzimas urease e arginase em solo do cerrado sob sistema de Integração Lavoura Pecuária e Floresta.

2016