Purification, characterization, and specificity determination of a new serine protease secreted by penicillium waksmanii

The purpose of this work was to purify a protease from Penicillium waksmanii and to determine its biochemical characteristics and specificity. The extracellular protease isolated that was produced by P. waksmanii is a serine protease that is essential for the reproduction and growth of the fungus. The protease isolated showed 32 kDa, and has optimal activity at pH 8.0 and 35 C towards the substrate Abz-KLRSSKQ-EDDnp. The protease is active in the presence of CaCl2, KCl, and BaCl, and partially inhibited by CuCl2, CoCl2 and totally inhibited by AlCl3 and LiCl. In the presence of 1 M urea, the protease remains 50 % active. The activity of the protease increases 60 % when it is exposed to 0.4 % nonionic surfactant-Triton X-100 and loses 10 % activity in the presence of 0.4 % Tween-80. Using fluorescence resonance energy transfer analysis, the protease showed the most specificity for the peptide Abz-KIRSSKQ-EDDnp with k cat/K m of 10,666 mM-1 s-1, followed by the peptide Abz-GLRSSKQ-EDDnp with a k cat/K m of 7,500 mM -1 s-1. Basic and acidic side chain-containing amino acids performed best at subsite S1. Subsites S2, S3, S′ 2, and S′ 1, S ′ 3 showed a preference for binding for amino acids with hydrophobic and basic amino acid side chain, respectively. High values of k cat/K m were observed for the subsites S2, S3, and S′ 2. The sequence of the N-terminus (ANVVQSNVPSWGLARLSSKKTGTTDYTYD) showed high similarity to the fungi Penicillium citrinum and Penicillium chrysogenum, with 89 % of identity at the amino acid level. © 2012 Springer Science+Business Media New York.

On the electrochemical behavior of Cu-16%Zn-6.5%Al alloy containing the β'-phase (martensite) in borate buffer

In this work, the electrochemical behavior of Cu-16(wt.%)Zn-6.5(wt.%)Al alloy containing the β'-phase (martensite) was studied in borate buffer solution (pH 8.4) by means of open-circuit potential (EOC), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The alloy EOC was -0.29 V vs. Hg/HgO/OH-, similar to that of pure copper in this medium, indicating that the processes which occur on the alloy surface are mainly governed by copper. EIS response was related to the dielectric and transmission properties of the complex oxide layer. The CVs showed peaks concerning the redox reactions for copper and zinc. These peaks were assigned to the formation and reduction of copper and zinc species. Furthermore, they showed that the copper oxidation was suppressed by the presence of zinc and aluminum in the alloy composition. The copper and zinc oxidation to form complex oxide layers and the reduction of the different metallic oxides generated in the anodic potential scan suggest that a solid state reaction could determine the metallic oxide formation. © 2013 Elsevier Ltd. All rights reserved.

Participação da ORF XAC3629 na regulação do operon de resistência a cobre copAB em Xanthomonas citri subsp. citri

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Construção de genossensor amperométrico para diagnóstico da hepatite C baseado em monocamadas auto montadas e detecção não marcada

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Metallo-chemotherapy of plant diseases /

Mode of access: Internet.

Facile conversion of electron rich benzylic hydrocarbons to carbonyl compounds by peroxydisulphate and copper ions

A convenient method for the conversion of electron rich benzylic hydrocarbons to carbonyl compounds is reported.

A XANES study of the K-absorption edge of copper in some of its compounds and use of the same in the determination of bond length

XANES in the K-edge of copper in the systems CuO, Cu(OH)2, La2CuO4, Cu3AsO4 and CuOHF have been investigated and transitions have been assigned to the observed structures. The measurements have been used for calculating the first coordination bond distance in the above systems. It is observed that the values so determined agree fairly well with crystallographic values.

Effects of silicon addition on the electrical and magnetic properties of copper-doped (La,Ca)MnO3 compounds

In this paper we report about the electrical properties of La 0.7Ca0.3MnO3 compounds substituted by copper on the manganese site and/or deliberately contaminated by SiO2 in the reactant mixture. Several phenomena have been observed and discussed. SiO2 addition leads to the formation of an apatite-like secondary phase that affects the electrical conduction through the percolation of the charge carriers. On the other hand, depending on the relative amounts of copper and silicon, the temperature dependence of the electrical resistivity can be noticeably modified: our results enable us to compare the effects of crystallographic vacancies on the A and B sites of the perovskite with the influence of the copper ions substituted on the manganese site. The most original result occurs for the compounds with a small ratio Si/Cu, which display double-peaked resistivity vs. temperature curves. © 2003 Elsevier B.V. All rights reserved.

Self-Assembly from Two-Dimensional Layered Networks to Tetranuclear Structures: Syntheses, Structures, and Properties of Four Copper-Thiacalix[4]arene Compounds

Two new copper-thiacalix[4]arene compounds, [Cu-2(1)-Cl-2(H(4)TC4A)](CH3OH) (1) and [Cu(I)2Cl(2)(H(4)PTC4A)](CH3OH)(CHCl3)(0.5) (2) (where H(4)TC4A = p-tert-butylthiacalix[4]arene and H(4)PTC4A = p-phenylthiacalix[4]arene), were synthesized by the solvothermal method in the mixed CH3OH/CHCl3 (1: 1) solvent and reassembled in air at room temperature to two other structures, [(Cu4Cl3)-Cl-II(HCO2)(TC4A)(CH3-OH)(2)(H2O)](CHCl3)(CH3OH)(2.7) (3) and [(Cu4Cl4)-Cl-II(PTC4A)(CH3OH)(4)] (4), respectively. All these four compounds were characterized by TG analyses, FTIR spectroscopy, and singlecrystal X-ray diffraction analyses. Compounds 1 and 2 feature two-dimensional layered networks, while compounds 3 and 4 are assembled by some tetranuclear units.

PH-Dependent syntheses and structures of two Copper(II)/Phenanthroline/p-Sulfonatocalix[4]arene supramolecular compounds with 1D water-filled channels

Two copper-organic framework supramolecular assemblies of p-sulfonatocalix[4]arene and 1,10-phenanthroline Cu-2[C12H8N2][C28H20S4O16][H2O](23.5) (1) and Cu-3[C12H8N2](3)[C28H19S4O16]Cl[H2O](17.6) (2) were obtained by pH-dependent synthesis at room temperature. Both structures show ID water-filled channels (rectangular shape in I and triangular in 2) with the solvent-accessible volume occupying 30.8% (1) and 24.2% (2) of the unit-cell volume, respectively. The calixarene molecules in both structures assume analogous cone shapes of C-2 nu symmetry instead of the conventional C-4 nu symmetry. Their connecting to different amounts of copper/phenanthroline cations leads to the formation of different structures.

A study of catalysis of copper-aluminium hydrotalcite-like compounds in the phenol hydroxylation

Copper-Aluminium Hydrotalcite-like compounds are synthesized by coprecipitation and characterized with XRD and IR. Catalysis of the above mentioned HTLcs are investigated in the phenol hydroxylation, good results are obtained. Meanwhile, the effects of the ratio of Cu/Al, reaction temperature, reaction medium and pH of reaction system are discussed, The reaction mechanism is also proposed.

Catalysis of copper-containing transition metal hydrotalcite-like compounds in the phenol hydroxylation with hydrogen peroxide

Hydrotalcite-like compounds containing carbonate ion as the interlayer anion were prepared by coprecipitation under low supersaturation condition by mixing an aqueous solution of metal nitrates with an aqueous solutions of NaOH and Na2CO3, at room temperature, maintaining pH = 8-10 with vigorous stirring, Following the mixing, the resulting heavy slurry was aged at 353 K for 18 h with vigorous stirring, The precipitate was then filtered, washed several times with hot distilled water and dried in air at 353 K overnight, In this way, CuMI AlCO3-HTLcs and M-I AlCO3-HTLcs were synthesized and characterized by means of XRD and IR, The catalysis of the above mentioned HTLcs were investigated in the phenol hydroxylation with H2O2. The results indicated that all of the copper-containing HTLcs had a higher catalytic activity in the reaction, However, those catalysts that did not contain copper had no catalytic activity in this reaction, This means that copper was the active center in the phenol hydroxylation. Meanwhile, the mechanism was also proposed, which could be used to explain the main reason for higher activity for CuCuAlCO3-HTLcs in the phenol hydroxylation and the effect of Mg2+, Zn2+, Co2+, Ni2+ on activity of CuMI AlCO3-HTLcs.