10 research outputs found
Síntese do 5-Acetóxi 7,7-Dimetóxi-Biciclo [2,2,1] hepta-2-eno enantiomericamente puro a partir do hexaclorociclopentadieno
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Síntese do 7,7-Dimetoxi- Biciclo [2,2,1] Hepta-2-Eno a partir do Hexaclorociclopenta-Dieno
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Variação percentual de produtos na reação de acetilação do isodrin em função da temperatura e tempo de reação
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Síntese do Endo-Exo Tetraciclico [6.2.1.33,6.02,7]dodec-9,10-Epoxi-4-Ona a partir do aldrin
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Steady-state kinetics of indole-3-glycerol phosphate synthase from Mycobacterium tuberculosis
No full textIndole-3-glycerol phosphate synthase (IGPS) catalyzes the irreversible ring closure of 1-(o-carboxyphenylamino)-1-deoxyribulose 5-phosphate (CdRP), through decarboxylation and dehydration steps, releasing indole-3-glycerol phosphate (IGP), the fourth step in the biosynthesis of tryptophan. This pathway is essential for Mycobacterium tuberculosis virulence. Here we describe the cloning, expression, purification, and kinetic characterization of IGPS from M. tuberculosis. To perform kinetic studies, CdRP was chemically synthesized, purified, and spectroscopically and spectrometrically characterized. CdRP fluorescence was pH-dependent, probably owing to excited-state intramolecular proton transfer. The activation energy was calculated, and solvent isotope effects and proton inventory studies were performed. pH-rate profiles were carried out to probe for acid/base catalysis, showing that a deprotonated residue is necessary for CdRP binding and conversion to IGP. A model to describe a steady-state kinetic sequence for MtIGPS-catalized chemical reaction is proposed.</p
Nickel-containing di-charged imidazolium ligand with high crystalline organization. Interception and characterization of a transient carbene/cation species
No full textInternational audienceNew nickel-containing di-charged imidazolium-based molten salt (2) was prepared by treatment of nickel chloride with bis-(2-(3-methylimidazolium-1-yl)ethyl)ether dichloride (1) in good yield. This compound has been fully characterized by elemental analysis, polarized optical microscopy (POM), differential scanning calorimetry (DSC), powder and single-crystal X-ray diffraction, and electrospray mass spectrometry. X-ray diffraction studies of 2 revealed a quite interesting 3D organization whereas cations and anions each arrange in individual chains, which are themselves connected in an extended, columnar-type network. Furthermore the presence of [NiCl4]2− unit in compound 2 induces a 3D crystalline arrangement much higher than that observed for compound 1. The ESI(+)-MS studies show the same set of fragments detected for both compound 1 and 2 displaying similar losses including the presence of a di-charged molecule. The fragmentation of nickel-containing compound 2 gave a very high intense cation-carbene ion of m/z 235, suggesting an additional stabilization by the presence of [NiCl4]2− unit in the structure of 2 related to the low intensity signal found for 1 in the same m/z
On the use of 2,1,3-benzothiadiazole derivatives as selective live cell fluorescence imaging probes
No full textNewly designed 2,1,3-benzothiadiazole-containing fluorescent probes with four excited state intramolecular proton transfer (ESIPT) sites were successfully tested in live cell-imaging assays using a confluent monolayer of human stem-cells (tissue). All tested dyes were compared with the commercially available DAPI and gave far better results. (c) 2010 Elsevier Ltd. All rights reserved.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPESCNPqConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Financiadora de Estudos e Projetos (FINEP)FINEPFinatecFinatecFAPESPFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPDFFAPD
Synthesis and enzymatic evaluation of the guanosine analogue 2-amino-6-mercapto-7-methylpurine ribonucleoside (MESG): insights into the phosphorolysis reaction mechanism based on the blueprint transition state: SN1 or SN2?
No full textA modified experimental procedure for the synthesis of MESG (2-amino-6-mercapto-7-methylpurine ribonucleoside) 1 has been successfully performed and its full characterization is presented. High resolution ESI(+)-MSMS indicates both the nucleoside bond cleavage as the main fragmentation in the gas phase and a possible SN1 mechanism. Ab initio transition state calculations based on the blue print transition state support this mechanistic rationale and discard an alternative SN2 mechanism. Assays using purine nucleoside phosphorylase (PNP) enzyme (human and M. tuberculosis sources) indicate its efficiency in the phosphorolysis of MESG and allow the quantitative determination of inorganic phosphate in real time assay
