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21.
Pedro A. Fernandes Elsa S. Henriques Vineet Pande Maria. J. Ramos Ana R. R. Maia André A. S. Almeida Bruno F. B. Silva Carla M. S. Ribeiro César F. B. Ribeiro David S. M. Ribeiro Diana A. P. Fonseca Eva M. S. Cunha Filipe R. N. C. Maia Joana A. A. Pereira João P. G. Pacheco Joaquim A. A. D. Ferreira Liliana R. C. Matos Manuel A. B. P. Pinto Maria C. S. Borges Paulo J. C. R. Magalhães Pedro F. R. D. Teixeira Pedro N. B. C. Veloso Ricarte J. F. Ferreira Sandro S. Gomes Tiago F. Barros Tiago S. J. T. Selão Virgínia M. M. C. Fernandes 《Theoretical chemistry accounts》2005,113(4):197-204
We present a series of new inhibitors of the association between nuclear factor kappa B (NF-B) and the corresponding B site in DNA. They were designed using the lead compound 15-deoxy-12,14 -prostaglandin J2 (PGJ2), which is a natural product with demonstrated inhibitory efficiency for this system. First, the binding mode of PGJ2 to NF-B was unraveled by GOLD docking calculation. Subsequently, substitutions were made to PGJ2 to optimize its association with NF-B. Care was taken not to strongly increase the reactivity of the new compounds, and to keep the overall shape, size and hydrophilicity of the lead compound, which should render them a similar bioavailability. Molecular mechanics calculations were performed to decide on the suitability of the substitutions, and to evaluate the energies of association with NF-B. Density functional theory calculations were performed also to study the overall reactivity of the substituted drugs towards NF-B. Important general conclusions were obtained, concerning the improvement of these natural inhibitors; namely, a set of rational methodologies were deduced to improve the association between the PGJ2 derivatives and NF-B, and their efficiency demonstrated by generating a set of substituted complexes, some of them with a very much increased affinity for NF-B, opening new doors to enlarge the therapeutic capabilities of this class of drugs. 相似文献
22.
The use of an amperometric biosensor for the salicylate determination in blood serum is described. The biosensor is based on salicylate hydroxylase (EC 1.14.13.1) electropolymerized onto a glassy carbon-working electrode with polypyrrole and glutaraldehyde, to improve the biosensor lifetime. The hexacyanoferrate (II) was also incorporated to work as a redox mediator to minimize possible interferences. The salicylate is enzymatically converted to catechol, which is monitored amperometrically by its electrooxidation at+0.170 V versus SCE (saturated calomel electrode). Salicylate determination was carried out maintaining the ratio between beta-NADH and salicylate at 4:1 (30 degrees C). The amperometric response of the biosensor was linearly proportional to the salicylate concentration between 2.3x10(-6) and 1.4x10(-5) mol l(-1), in 0.1 mol l(-1) phosphate buffer (pH 7.8), containing 0.1 mol l(-1) KCl and 5.0x10(-4) mol l(-1) Na(2)H(2)EDTA, as supporting electrolyte. The recovery studies, in the presence of several interfering compounds, showed recoveries between 96.4 and 104.8%. The useful lifetime of the biosensor in the concentration range evaluated was at least 40 days, in continuous use. Blood serum samples analyzed by this biosensor showed a good correlation compared to the spectrophotometric method (Trinder) used as reference, presenting relative deviations lower than 7.0%. 相似文献
23.
R. C. Orlando E. A. N. Fernandes M. Szikszay 《Journal of Radioanalytical and Nuclear Chemistry》1994,179(2):259-266
This study comprises Tertiary sediments (clays, silts, and fine clayey sands) from the unsaturated zone of the Experimental Station in the University of São Paulo, taken from a nine meters depth profile; ten samples were separated in bulk and <53 m fractions. Chemical composition was determined by INAA to ascertain the distribution of trace elements throughout the sediment deposition, and to establish the background parameters, useful for mobilization studies of such elements after industrial waste disposal. 相似文献
24.
A flow injection system for the automatic determination of total phosphorus in beer is described. The developed manifold uses a two-stage photooxidation/thermal digestion procedure together with oxidizing and hydrolyzing reagents to convert all forms of phosphorus compounds to orthophosphate. Polyphosphates are hydrolyzed by acid and heat, and organo-phosphates are digested by UV-catalyzed peroxodisulfate oxidation. The orthophosphate formed is then spectrophotometrically determined by the phosphomolybdenum blue reaction, using stannous chloride as reducing agent. The results obtained for a set of 19 beer samples (with concentrations from 120 to 735 mg P/L) were in good agreement with the reference method, the maximum relative deviation found being 4.7%. Relative standard deviations for ten consecutive determinations were lower than 1.5%, and a detection limit of 1 mg P/L was achieved. 相似文献
25.
H. T. Fukuma E. A. De Nadai Fernandes A. L. Quinelato 《Journal of Radioanalytical and Nuclear Chemistry》2003,257(1):117-121
High-uranium phosphate rock from Itataia, Brazil, was milled for wet-process phosphoric acid production using the dihydrate method. Uranium contained in the phosphoric acid was recovered by solvent extraction. The distribution of long-lived natural radionuclides of the 238U and 232Th decay series involved in these operations was evaluated. 226Ra, 228Ra and 210Pb were found to predominate in the phosphogypsum, while 228Th, 230Th and 232Th in the uranium-free phosphoric acid. Thorium is removed from the phosphoric acid by solvent extraction to produce a NORM-free phosphoric acid. 相似文献
26.
Fernandes L. P. Éhen Zs. Moura T. F. Novák Cs. Sztatisz J. 《Journal of Thermal Analysis and Calorimetry》2004,78(2):557-573
Thermoanalytical techniques, being rapid and un-expensive have been used for the investigation of the cyclodextrin inclusion
complexes for three decades. The conventional thermoanalytical techniques (TG and DTA/DSC) follow the thermal properties of
the uncomplexed compounds. Consequently, the inclusion complex formation as well as the liberation of the entrapped guest
cannot be followed. Monitoring the products of the thermal fragmentation of parent cyclodextrin and the included molecule(s),
applying TG-MS combined technique provides evidence concerning the inclusion complex formation, and besides, gives selective
signal to follow the decomposition of the cyclodextrin inclusion complexes. b-cyclodextrin inclusion complexes of Thymol and
Lippia sidoides Cham essential oil extract have been prepared and investigated using conventional and combined (TG-MS) thermoanalytical techniques.
The evolved gas analysis proved the inclusion complex formation between the host and guests. By the evaluation of the experimental
results the elaboration of the entrapped guests from the cyclodextrin cavity could be followed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
27.
Thermogravimetric (t.g.) and differential scanning calorimetric (d.s.c.) data have been used to study metal–amino acid interactions in adducts of general formula MnCl2 · ngly (gly = glycine, n = 0.7, 2.0, 4.0 and 5.0). All the prepared adducts exhibit only a one step mass loss associated with the release of glycine molecules, except for the 0.7gly adduct, which exhibits two glycine mass loss steps. From d.s.c. data, the enthalpy values associated with the glycine mass loss can be calculated: MnCl2 · 0.7gly = 409 and 399 kJ mol–1, MnCl2 · 2.0gly = 216 kJ mol–1, MnCl2 · 4.0gly = 326 kJ mol–1 and MnCl2 · 5.0gly = 423 kJ mol–1, respectively. The enthalpy associated with the ligand loss, plotted as function of the number of ligands for the n = 2.0, 4.0 and 5.0 adducts, gave a linear correlation, fitting the equation: H (ligand loss)/kJ mol–1 = 67 × (number of ligands, n) + 76. A similar result was achieved when the enthalpy associated with the ligand loss was plotted as a function of the
a(COO–) bands associated with the coordination through the carboxylate group, 1571, 1575 and 1577 cm–1, respectively, for the n = 2.0, 4.0 and 5.0 adducts, giving the equation H (ligand loss) /kJ mol–1 = 33.5 ×
a(COO–) /cm–1 – 52418.5. This simple equation provides evidence for the enthalpy associated with the ligand loss being very closely related to the electronic density associated with the metal–amino acid bonds. 相似文献
28.
An automatic procedure for the determination of ethanol in wines using a flow system based on multicommutation and enzymatic reaction is described. Alcohol oxidase was immobilized on aminopropyl glass beads and packed in an acrylic column. The peroxide due to enzymatic reaction with ethanol reacted with luminol and generated the chemiluminescence radiation that was monitored by using a laboratory-made detector based on photodiodes. The system manifold comprised a set of 3-way solenoid valves controlled by a microcomputer furnished with electronic interfaces, which ran on software written in Quick BASIC 4.5 to provide facilities to perform on-line sample dilution, reagent addition, and data acquisition. After system parameters optimization, ethanol samples were processed without prior pretreatment. The following suitable features were achieved: linear response ranging from 2.5 to 25% (v/v) ethanol, relative standard deviation of 1.8% (n = 10), detection limit of 0.3% (v/v) ethanol, sampling rate of 23 determinations per hour, and low reagent consumption of 0.23 mg luminol and 7 mg hexacyanoferrate (III) per determination. When the results were compared with those obtained using the AOAC Official Method, no significant difference at the 90% confidence level was observed. 相似文献
29.
G. L. Morgans S. M. Scalzullo M. A. Fernandes J. P. Michael W. A. L. van Otterlo 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(5):o309-o311
The title compound, C20H19NO5S2, crystallizes as an almost 2:1 mixture of two molecular orientations (described as Orient‐A and Orient‐B). The consequences of these two orientations is the formation of three types of N—H...O hydrogen‐bonded dimers in which the (Orient‐A + Orient‐A) dimers are likely to be the most stable, while the mixed (Orient‐A + Orient‐B) dimers are more frequent. Extra interactions in the form of C—H...O and C—H...π interactions act to further stabilize these dimers and probably allow the less energetically favourable (Orient‐A + Orient‐B) and (Orient‐B + Orient‐B) hydrogen‐bonded dimers to exist by preventing their conversion to (Orient‐A + Orient‐A)‐only hydrogen‐bonded dimers during the crystal‐growth process. 相似文献
30.
de Farias Robson Fernandes Martínez Leandro Airoldi Claudio 《Transition Metal Chemistry》2002,27(7):748-750
This paper describes the synthesis, characterization and a thermogravimetric (t.g.) study of 11 adducts of general formula MCl2·nL (M = Cu, Co and Sn; n = 1 and 2 for Sn, and 2 for Cu and Co; L = ethyleneurea eu, ethylenethiourea etu, and propyleneurea pu). The i.r. results shows that the eu and pu adducts are coordinated through oxygen, whereas for etu nitrogen is the coordination site. The (C=O) or (C=S) trend is: Cu > Co > Sn. The t.g. curves show that the adducts release ligand molecules in a single mass loss step. As regards considering adducts with the same stoichiometry, the observed thermal stability trend is: etu > pu > eu. 相似文献