A Simple and Fast Method for the Production and Characterization of Methylic and Ethylic Biodiesels from Tucum Oil via an Alkaline Route

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Thermostable conidial and mycelial alkaline phosphatases from the thermophilic fungus Scytalidium thermophilum

An extracellular (conidial) and an intracellular (mycelial) alkaline phosphatase from the thermophilic fungus Scytalidium thermophilum were purified by DEAE-cellulose and Concanavalin A-Sepharose chromatography. These enzymes showed allosteric behavior either in the presence or absence of MgCl2, BaCl2, CuCl2, and ZnCl2. All of these ions increased the maximal velocity of both enzymes. The molecular masses of the conidial and mycelial enzymes, estimated by gel filtration, were 162 and 132 kDa, respectively. Both proteins migrated on SDS-PAGE as a single polypeptide of 63 and 58.5 kDa, respectively, suggesting that these enzymes were dimers of identical subunits. The best substrate for the conidial and mycelial phosphatases was p-nitrophenylphosphate, but,beta -glycerophosphate and other phosphorylated compounds also served as substrates. The optimum pH for the conidial and mycelial alkaline phosphatases was 10.0 and 9.5 in the presence of AMPOL buffer, and their carbohydrate contents were about 54% and 63%, respectively. The optimum temperature was 70-75 degreesC for both activities. The enzymes were fully stable up to 1 h at 60 degreesC. These and other properties suggested that the alkaline phosphatases of S. thermophilum might be suitable for biotechnological applications.

Petrological and geochemical evolution of the alkaline Valle Chico Massif, southeastern Uruguay

The Valle Chico Massif is a member of the Early Cretaceous alkaline magmatic suite of rocks distributed around the Parana Basin. Three magmatic associations are recognized: (1) the Plutonic Association, characterized by syenites, quartz syenites, and syenogranites; (2) the Volcanic Association, mainly composed of porphyritic quartz trachytes; and (3) the Porphyritic Dike Association consisting of rhyolites and trachytes. Judging by their geochemical behavior, the rhyolites exhibit a weak peralkaline affinity, and are genetically connected by progressive melting processes, whereas the other lithologies have a metaluminous nature, and are products of mineral fractionation. An enriched mantle of Transamazonian age, geochemically similar to OIB, is postulated as a possible source.

MECHANISM OF ACTION OF COBALT IONS ON RAT OSSEOUS PLATE ALKALINE-PHOSPHATASE

Polidocanol-solubilized osseous plate alkaline phosphatase was modulated by cobalt ions in a similar way as by magnesium ions. For concentrations up to 1 mu M, the Chelex-treated enzyme was stimulated by cobalt ions, showing K-d = 6.0 mu M, V = 977.5 U/mg, and site-site interactions (n = 2.5). Cobalt-enzyme was highly unstable at 37 degrees C, following a biphasic inactivation process with inactivation constants of about 0.0625 and 0.0015 min(-1). Cobalt ions stimulated the enzyme synergistically in the presence of magnesium ions (K-d = 5.0 mu M; V = 883.0 U/mg) or in the presence of zinc ions (K-d = 75.0 mu M; V = 1102 U/mg). A steady-state kinetic model for the modulation of enzyme activity by cobalt ions is proposed.

Dependence of divalent metal ions on phosphotransferase activity of osseous plate alkaline phosphatase

Kinetic evidence for the role of divalent metal ions in the phosphotransferase activity of polidocanol-solubilized alkaline phosphatase from osseous plate is reported. Ethylenediamine tetreacetate, 1,10-phenanthrolin, and Chelex-100 were used to prepare metal-depleted alkaline phosphatase. Except for Chelex-100, either irreversible inactivation of the enzyme or incomplete removal of metal ions occurred. After Chelex-100 treatment, full hydrolase activity of alkaline phosphatase was recovered upon addition of metal ions. on the other hand, only 20% of transferase activity was restored with 0.1 mu M ZnCl2, in the presence of 1.0 M diethanolamine as phosphate acceptor. In the presence of 0.1 mM MgCl2, the recovery of transferase activity increased to 63%. Independently of the phosphate acceptor used, the transferase activity of the metal-depleted alkaline phosphatase was fully restored by 8 mu M ZnCl2 plus 5 mM MgCl2. In the presence of diethanolamine as phosphate acceptor, manganese, cobalt, and calcium ions did nor stimulate the transferase activity. However, manganese and cobalt-enzyme catalyzed the transfer of phosphate to glycerol and glucose. (C) 1997 Elsevier B.V.

ALLOSTERIC MODULATION BY ATP, CALCIUM AND MAGNESIUM-IONS OF RAT OSSEOUS PLATE ALKALINE-PHOSPHATASE

Alkaline phosphatase from rat osseous plate is allosterically modulated by ATP, calcium and magnesium at pH 7.5. At pH 9.4, the hydrolysis of ATP and PNPP follows Michaelis-Menten kinetics with K0.5 values of 154 muM and 42 muM, respectively. However, at pH 7.5 both substrates exhibit more complex saturation curves, while only ATP exhibited site-site interactions. Ca2+-ATP and Mg2+-ATP were effective substrates for the enzyme, while the specific activity of the enzyme for the hydrolysis of ATP at pH 7.5 was 800-900 U/mg and was independent of the ion species. ATP, but not PNPP, was hydrolyzed slowly in the absence of metal ions with a specific activity of 140 U/mg. These data demonstrate that in vitro and at pH 7.5 rat osseous plate alkaline phosphatase is an active calcium or magnesium-activated ATPase.

EFFECT OF THE ADDITION OF CR AND NB ON THE MICROSTRUCTURE AND ELECTROCHEMICAL CORROSION OF HEAT-TREATABLE AL-ZN-MG ALLOYS

The effect of the addition of Cr and Nb on the microstructure and the electrochemical corrosion of the weldable, high-strength and stress corrosion cracking (SCC) resistant Al-5%Zn-1.67%Mg-0.23%Cu alloy (H) has been studied. Combined additions of the alloying elements, J (with Nb), L (with Cr) and O (with Cr and Nb) and different heat treatments, ST (cold-rolled), A (annealed), F (quenched), B (quenched and aged) and C (quenched in two steps and aged), to obtain different microstructures and hardness have been performed. To correlate the electrochemical corrosion with the microstructure of the specimens, corrosion potential (E(cor)) measurements in different chloride solutions were performed and optical microscopy, SEM, TEM and EDX were applied. In chloride solutions containing dissolved O-2 or H2O2, the present alloys were polarized up to the pitting attack. It was shown that the E(cor) measurements were very sensitive to the alloy composition and heat treatment, increasing in the order H < J < L < O < Al (for a given heat treatment) and F < A approximate to ST < B < C (for a given alloy). The MgZn2 precipitates of the annealed (A) and cold-rolled (ST) specimens were dissolved in chloride solutions containing oxidizing agents and pitting attack was shown to develop in the cavities where the precipitates were present. In the specimens B and C, the compositions of the precipitate free zones was found to be equal to that of the matrix solid solution and preferential intergranular attack was not evident, this being in agreement with their SCC resistance. The addition of Cr and Nb increased the pitting corrosion resistance. The effects of Cr and Nb were additive, that of Cr being predominant, either, in the E(cor) shift or in the increase in the pitting corrosion resistance.

The hydrogen evolution reaction on codeposited Ni-hydrogen storage intermetallic particles in alkaline medium

The hydrogen evolution reaction (HER) was studied on Ni-LaNi5 and Ni-MmNi(3.4)Co(0.8)Al(0.8) electrode materials in 1 mol dm(-3) NaOH solution. The steady-state polarization curves and electrochemical impedance spectroscopy experimental data showed a pronounced improvement in HER kinetics when these electrode materials were used. The electrochemical results are in accordance with the Volmer-Heyrovsky mechanism. The kinetic results indicate a more effective improvement in the Heyrovsky step, suggesting an electrocatalytic synergistic effect of the hyper-electronic character of the Ni and the hypo-electronic character of the rare-earth element on the electrode surface. (C) 2000 International Association for Hydrogen Energy. Published by Elsevier B.V. Ltd. All rights reserved.

Application of voltammetric technique to the analysis of indanthrene dye in alkaline solution

The Indanthrene Olive Green B (C.I. Vat Green 3; C.I. 69500), VG3 dye, a vat dye bearing an anthraquinonoid group and a ketonic group, can be detected by differential pulse voltammetry in alkaline solution using glassy carbon electrode. on the adsorbed form the dyes are reduced into three cathodic steps at -0.54 V, -0.65 V and -0.93 V vs Ag/AgCl. The leuco form generated after previous electrolysis at controlled potential of -1 V can be detected by voltammetry due to its reoxidation peak at -0.08 V. An analytical method is proposed for determining the vat dye using modified glassy carbon electrode by electrochemical activation in alkaline medium. Linear relationship was observed between l(Pu) vs concentration from I X 10(-5) mol L-1 to 6.0 X 10(-4) mol L-1. The detection limit was calculated to be 9.3 X 10(-6) mol L-1. (c) 2005 Elsevier Ltd. All rights reserved.

PRODUCTION OF MICROBIAL ALKALINE CELLULASE AND STUDIES OF THEIR CHARACTERISTICS

In order to obtain cellulases that improve the detergency of laundry detergent products, two alkalophilic microorganims, Bacillus sp B38-2 and Streptomyces sp S36-2, were isolated from soil and compost by incubating samples in enrichment culture medium containing CMC and Na2CO3 at pH9.6. It was found that they secrete a constitutive extracellular alkaline carboxymethyl cellulase (CMCase) in high quantity. The maximum enzyme activity was observed between 48hr to 72 hr at 30-degrees-C for the Streptomyces and between 72hr to 96hr at 35-degrees-C for the Bacillus. The optimum pH and temperature of the crude enzyme activities ranged from 6.0 to 7.0 at 55-degrees-C for the Streptomyces and 7.0 to 8.0 at 60-degrees-C for the Bacillus. Two crude CMCases activities were termostable at 45-degrees-C for 1hr and the both crude enzyme activities of the Bacillus as of the Streptomyces were stable at pH 5.0 to 9.0 after pH treatments in various buffer solutions at 30-degrees-C for 24hr.