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21.
Rodrigo O.M.A. de Souza Lilian M.C. Matos Ingrid C.R. Costa Selma G.F. Leite O.A.C. Antunes 《Tetrahedron letters》2009,50(17):2017-1605
The present Letter details our findings on the lipase-catalyzed Michael reactions between primary or secondary amines and acrylonitrile. Several lipases were evaluated, and good results were obtained leading to the formation of Michael adducts in shorter reaction times than the uncatalyzed reactions. 相似文献
22.
Mahmut Erzengin Ismet Basaran Umit Cakir Aynur Aybey Selma Sinan 《Applied biochemistry and biotechnology》2012,168(6):1540-1548
Human serum paraoxonase 1 (PON1; EC 3.1.8.1) is a high-density lipoprotein associated, calcium-dependent enzyme that hydrolyses aromatic esters, organophosphates and lactones and can protect the low-density lipoprotein against oxidation. In this study, in vitro inhibition effect of some dihydroxy coumarin compounds namely 6,7-dihydroxy-3-(2-methylphenyl)-2H-chromen-2-one (A), 6,7-dihydroxy-3-(3-methylphenyl)-2H-chromen-2-one (B) and 6,7-dihydroxy-3-(4-methylphenyl)-2H-chromen-2-one (C) on purified PON1 were investigated by using paraoxon as a substrate. PON1 was purified using two-step procedures, namely ammonium sulphate precipitation and Sepharose-4B-l-tyrosine-1-naphthylamine hydrophobic interaction chromatography. The purified enzyme had a specific activity of 11.76?U/mg. The dihydroxy coumarin derivatives of A and B compounds inhibited PON1 enzyme activity in a noncompetitive inhibition manner with K i of 0.0080?±?0.256 and 0.0003?±?0.018?mM values, respectively. C compound exerted an uncompetitive inhibition of PON1 enzyme activity with K i of 0.0010?±?0.173?mM. Moreover, dihydroxy coumarin derivatives of A, B and C compounds were effective inhibitors on purified human serum PON1 activity with IC50 of 0.012, 0.022 and 0.003?mM values, respectively. IC50 value of unsubstituted 6,7 dihydroxy coumarin was found as 0.178?mM. The present study has demonstrated that PON1 activity is very highly sensitive to studied coumarin derivatives. 相似文献
23.
Luciana A. I. de Azeredo Leda R. Castilho Selma G. F. Leite Rosalie R. R. Coelho Denise M. G. Freire 《Applied biochemistry and biotechnology》2003,108(1-3):749-755
Streptomyces are important microorganisms because of their capacity to produce numerous bioactive molecules. In the present work protease
production, by Streptomyces sp. 594 isolated from a Brazilian Cerrado soil, was maximized by optimizing a low-cost culture medium composition (casitone
and sugarcane molasses) using statistical experimental design. The final protease activity (56 U/mL) was 2.8-fold and 58-fold
higher than that obtained in the beginning of this study, and in a previous work, using an actinomycete selection medium,
respectively. Protease production, not growth associated, appeared to be modulated by an inducer system, whereby the C/N ratio
seemed to play a significant role. 相似文献
24.
Electrochemical investigations of [bis(triphenylphosphoranylidene)ammonium)][tris(2-(diphenylphosphino)thiaphenolato)ruthenate(II)], PPN[Ru(DPPBT)(3)] (1), and [(bis(2-(diphenylphosphino)thiaphenolato)methane)(2-(diphenylphosphino)thiaphenolato)ruthenium(II)] chloride, [Ru((DPPBT)(2)CH(2))(DPPBT)]Cl (2) are reported. Complex 1 is oxidized reversibly in a metal-centered event by one electron at a potential of +455 mV (vs Ag/AgCl) to the ruthenium(III) derivative [tris(2-(diphenylphosphino)thiaphenolato)ruthenium(III)], 3. Complex 3 can also be prepared by iodine oxidation of 1 in acetonitrile. Oxidation of 3 in acetonitrile is reversible on a cyclic voltammetry time scale but irreversible upon bulk oxidation yielding Ru-X. Monitoring the oxidation of 3 by UV-visible spectroscopy reveals a proposed metal-coordinated thiyl radical intermediate with a maximum absorbance at 850 nm. This intermediate decays at a temperature of -20 degrees C with a rate constant of (5.82 +/- 0.73) x 10(-)(3) s(-)(1) with a small, positive deltaH and a large, negative deltaS. Ru-X can be oxidized reversibly to Ru-Y at a potential of +806 mV but cannot be reduced. Complex 2 is reversibly oxidized by one electron in a metal-centered event to 4 at a potential of +767 mV. 相似文献
25.
Selma Giorgio Edlaine Linares Margareth de L. Capurro Antonio G. de Bianchi Ohara Augusto 《Photochemistry and photobiology》1996,63(6):750-754
Peroxynitrite, the potent oxidant formed by the fast reaction between nitric oxide and superoxide anion, has been suggested to be the reactive intermediate responsible for some of the pathologies associated with an overproduction of nitric oxide. In this report, we demonstrate that both nitric oxide and peroxynitrite are formed during infection of the susceptible mouse strain, BALBk, with Leishmania amazonensis. Nitric oxide was detected as the nitrosyl hemoglobin complex by EPR analysis of blood drawn from mice at 35 , 64 and 148 days of infection. The levels of nitrosyl hemoglobin complex increased with disease evolution, which in the murine model used is characterized by skin lesions, ulceration and visceral-ization of the parasites. Peroxynitrite formation was inferred from immunoreaction of homogenates obtained from footpad lesions in the late stages of the infection with anti-nitrotyrosine antibody; homogenates from parasites drawn from the lesions were also immunoreactive, although to a lesser extent. Analysis of protein homogenates by gel electrophoresis and western blots suggests that peroxynitrite may degrade proteins in vivo, in addition to nitrating them. The results demonstrate that peroxynitrite is formed during murine leishmaniasis and may play a role in the aggravation of the disease. 相似文献
26.
Aline de Souza Ramos Joyce Benzaquem Ribeiro Leonardo Vazquez Selma Gomes Ferreira Leite Francisco Radler de Aquino Neto 《Tetrahedron letters》2009,50(52):7362-6129
The enantioselective reduction of ethyl benzoylacetate (EBA) into ethyl (S)-3-hydroxy-3-phenylpropanoate (S-HPPE) by nine yeast strains and three filamentous fungi strains is described. The conversion obtained was in the range 0-89% and the enantiomeric excess was 100% in many cases. Conversion levels were higher when the reduction was performed with microorganisms immobilized in calcium alginate and enantioselectivity remained excellent. Some reaction’s conditions of bioreduction by immobilized cells of Rhodotorula rubra were studied using a 25-2 fractional factorial design. 相似文献
27.
28.
Su Xudong Feng Meng Rogers Shane Holsen Thomas M. Thagard Selma Mededovic 《Plasma Chemistry and Plasma Processing》2019,39(3):577-596
Plasma Chemistry and Plasma Processing - This work investigates the effect of high voltage (HV) electrode material of a point-plane plasma reactor on the inactivation rate of E. coli in both direct... 相似文献
29.
Shakir Zahraa S. AL-Jawad Selma M. H. Ahmed Duha S. 《Journal of Sol-Gel Science and Technology》2021,100(1):115-131
Journal of Sol-Gel Science and Technology - In recent years, cobalt attracted large interest in biological application, due to its biocompatibility and low toxicity. The synthesis of Co... 相似文献
30.
AL-Jawad Selma M. H. Imran Natheer Jamal Aboud Kahlaa H. 《Journal of Sol-Gel Science and Technology》2021,100(3):423-439
Journal of Sol-Gel Science and Technology - Mn-CdS nanoflowers were successfully deposited using hydrothermal technique at 150 °C for 2 h. The effect of changing the dopant... 相似文献