排序方式: 共有83条查询结果,搜索用时 15 毫秒
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Priscila Lamb Wink Zilpa Adriana Sanchez Quitian Leonardo Astolfi Rosado Valnes da Silva Rodrigues Júnior Guilherme Oliveira Petersen Daniel Macedo Lorenzini Thiago Lipinski-Paes Luis Fernando Saraiva Macedo Timmers Osmar Norberto de Souza Luiz Augusto Basso Diogenes Santiago Santos 《Archives of biochemistry and biophysics》2013
Tuberculosis (TB) is a major global health threat. There is a need for the development of more efficient drugs for the sterilization of the disease’s causative agent, Mycobacterium tuberculosis (MTB). A more comprehensive understanding of the bacilli’s nucleotide metabolic pathways could aid in the development of new anti-mycobacterial drugs. Here we describe expression and purification of recombinant iunH-encoded nucleoside hydrolase from MTB (MtIAGU-NH). Glutaraldehyde cross-linking results indicate that MtIAGU-NH predominates as a monomer, presenting varied oligomeric states depending upon binding of ligands. Steady-state kinetics results show that MtIAGU-NH has broad substrate specificity, accepting inosine, adenosine, guanosine, and uridine as substrates. Inosine and adenosine displayed positive homotropic cooperativity kinetics, whereas guanosine and uridine displayed hyperbolic saturation curves. Measurements of kinetics of ribose binding to MtIAGU-NH by fluorescence spectroscopy suggest two pre-existing forms of enzyme prior to ligand association. The intracellular concentrations of inosine, uridine, hypoxanthine, and uracil were determined and thermodynamic parameters estimated. Thermodynamic activation parameters (Ea, ΔG#, ΔS#, ΔH#) for MtIAGU-NH-catalyzed chemical reaction are presented. Results from mass spectrometry, isothermal titration calorimetry (ITC), pH-rate profile experiment, multiple sequence alignment, and molecular docking experiments are also presented. These data should contribute to our understanding of the biological role played by MtIAGU-NH. 相似文献
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da Silva OG Rossignoli Pde S Carrillo-Sepúlveda MA Barreto-Chaves ML Chies AB 《Peptides》2011,32(1):112-117
Although angiotensin II-induced venoconstriction has been demonstrated in the rat vena cava and femoral vein, the angiotensin II receptor subtypes (AT1 or AT2) that mediate this phenomenon have not been precisely characterized. Therefore, the present study aimed to characterize the pharmacological receptors involved in the angiotensin II-induced constriction of rat venae cavae and femoral veins, as well as the opposing effects exerted by locally produced prostanoids and NO upon induction of these vasomotor responses. The obtained results suggest that both AT1 and AT2 angiotensin II receptors are expressed in both veins. Angiotensin II concentration-response curves were shifted toward the right by losartan but not by PD 123319 in both the vena cava and femoral vein. Moreover, it was observed that both 10−5 M indomethacin and 10−4 M L-NAME improve the angiotensin II responses in the vena cava and femoral vein. In conclusion, in the rat vena cava and femoral vein, angiotensin II stimulates AT1 but not AT2 to induce venoconstriction, which is blunted by vasodilator prostanoids and NO. 相似文献
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Moreno RG Alipázaga MV Gomes OF Linares E Medeiros MH Coichev N 《Journal of inorganic biochemistry》2007,101(5):866-875
S(IV) (SO(2),HSO(3)(-)andSO(3)(2-)) autoxidation catalyzed by Cu(II)/tetraglycine complexes in the presence of DNA or 2'-deoxyguanosine (dGuo) resulted in DNA strand breaks and formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo), respectively. Ni(II), Co(II) or Mn(II) (1.0x10(-4)M) complexes had much smaller effects. Cu(II)/tetraglycine (1.0x10(-4)M) in the presence of Ni(II) or Mn(II) (10(-7)-10(-6)M) and S(IV) showed remarkable synergistic effect with these metal ions producing a higher yield of 8-oxodGuo. Oxidation of dGuo and DNA damage were attributed to oxysulfur radicals formed as intermediates in S(IV) autoxidation catalyzed by transition metal ions. SO*(3)(-) and HO* radicals were detected by EPR-spin trapping experiments with DMPO (5,5-dimethyl-1-pyrroline-N-oxide). 相似文献
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Mariana G. Bender Gustavo R. Machado Paulo José de Azevedo Silva Sergio R. Floeter Cassiano Monteiro-Netto Osmar J. Luiz Carlos E. L. Ferreira 《PloS one》2014,9(10)
In the last decades, a number of studies based on historical records revealed the diversity loss in the oceans and human-induced changes to marine ecosystems. These studies have improved our understanding of the human impacts in the oceans. They also drew attention to the shifting baseline syndrome and the importance of assessing appropriate sources of data in order to build the most reliable environmental baseline. Here we amassed information from artisanal fishermen''s local ecological knowledge, fisheries landing data and underwater visual census to assess the decline of fish species in Southeastern Brazil. Interviews with 214 fishermen from line, beach seine and spearfishing revealed a sharp decline in abundance of the bluefish Pomatomus saltatrix, the groupers Epinephelus marginatus, Mycteroperca acutirostris, M. bonaci and M. microlepis, and large parrotfishes in the past six decades. Fisheries landing data from a 16-year period support the decline of bluefish as pointed by fishermen''s local knowledge, while underwater visual census campaigns show reductions in groupers'' abundance and a sharp population decline of the Brazilian endemic parrotfish Scarus trispinosus. Despite the marked decline of these fisheries, younger and less experienced fishermen recognized fewer species as overexploited and fishing sites as depleted than older and more experienced fishermen, indicating the occurrence of the shifting baseline syndrome. Here we show both the decline of multigear fisheries catches – combining anecdotal and scientific data – as well as changes in environmental perceptions over generations of fishermen. Managing ocean resources requires looking into the past, and into traditional knowledge, bringing historical baselines to the present and improving public awareness. 相似文献
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Claudia E. Thompson Cláudia L. Fernandes Osmar Norberto de Souza Loreta B. de Freitas Francisco M. Salzano 《Journal of molecular modeling》2010,16(5):919-928
The plant alcohol dehydrogenases (ADHs) have been intensively studied in the last years in terms of phylogeny and they have
been widely used as a molecular marker. However, almost no information about their three-dimensional structure is available.
Several studies point to functional diversification of the ADH, with evidence of its importance, in different organisms, in
the ethanol, norepinephrine, dopamine, serotonin, and bile acid metabolism. Computational results demonstrated that in plants
these enzymes are submitted to a functional diversification process, which is reinforced by experimental studies indicating
distinct enzymatic functions as well as recruitment of specific genes in different tissues. The main objective of this article
is to establish a correlation between the functional diversification occurring in the plant alcohol dehydrogenase family and
the three-dimensional structures predicted for 17 ADH belonging to Poaceae, Brassicaceae, Fabaceae, and Pinaceae botanical
families. Volume, molecular weight and surface areas are not markedly different among them. Important electrostatic and pI
differences were observed with the residues responsible for some of them identified, corroborating the function diversification
hypothesis. These data furnish important background information for future specific structure-function and evolutionary investigations. 相似文献
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Osmar J. LuizJr Ana Paula Balboni Guilherme Kodja Maurício Andrade Heloisa Marum 《Ichthyological Research》2009,56(1):96-99
An analysis of 79 underwater photographs of Manta birostris gathered over a period of nine years in a marine protected area in southeastern Brazil suggests a high predictability of
manta ray occurrences in the region during the austral winter (June–September). The reasons for this are probably related
to the seasonal oceanographic conditions, as characterized by the presence of a coastal front at the study site in winter
and consequent plankton enrichment, which provides a feeding opportunity for manta rays. In addition, a melanistic individual
in the Atlantic Ocean that is similar in color to the Pacific Ocean’s “black manta” is reported for the first time. 相似文献
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Osmar Norberto de Souza Rick L. Ornstein 《Journal of biomolecular structure & dynamics》2013,31(5):607-611
Abstract This report describes one 3000 ps and two 1500 ps molecular dynamic simulations on a TATA box containing dodecamer DNA duplex in a periodic box of TIP3P water molecules, using the AMBER 4.1 implementation of the particle-mesh Ewald method. We compare the effect of warmup protocol and simulation time length on the root-mean square deviation (RMSD) parameter. For the longer simulation, the RMSD computed for the 500–1000 ps time interval is representative of longer time intervals, including 500–3000 ps. The various warmup protocols do not appear to have a significant effect on the simulation results. Based on the present results, DNA sequence-dependent differences in RMSD, or related properties, should exceed two standard deviations before being attributed to non-simulation factors, such as warmup protocol and sampling time effects; we recommend a minimum criterion of at least a three standard deviation difference with a sampling period of at least 500–1000 ps. In addition, while end effects appear negligible there is a consistent dependence of RMSD on DNA helix length. 相似文献
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Bridge Tom C. L. Luiz Osmar J. Kuo Chao-Yang Precoda Kristin Madin Elizabeth M. P. Madin Joshua S. Baird Andrew H. 《Coral reefs (Online)》2020,39(2):271-279
Coral Reefs - Comparative lists of species’ extinction risk are increasingly being used to prioritise conservation resources. Extinction risk is most rigorously assessed using quantitative... 相似文献