Jack Kessler, Júlio Xandro Heck, Stuart W. Tanenbaum, Michael Flashner,
Neuraminidase from A . sialophilus was induced and purified asThe abbreviations used are: AcNeu, N-acetylneuraminic acid (I); AcNeu methyl ester, N-acetylneuraminic acid methyl ester (11); AcNeu-a-Me, N-acetylneuraminyl-a-methylglycoside (111); AcNeu-P-Me, N-acetylneuraminyl-P-methylglycoside (IV); AcNeu-a-4-MU, N-acetylneuraminyl-a-4-methylumbelliferylglycoside (V
Tópico(s): Enzyme function and inhibition
1982 - Elsevier BV | Journal of Biological Chemistry
Produção Nacional
Revisado por pares
Giandra Volpato, Marco Filice, Rafael C. Rodrigues, Júlio Xandro Heck, José M. Guisán, César Mateo, Marco Antônio Záchia Ayub,
This research describes the immobilization on glyoxyl, cyanogen bromide or octyl agarose beads of a purified lipase from Staphylococcus warneri strain EX17 (SWL), and the effect on its properties. The immobilization on glyoxyl-agarose at pH 10 and 25 °C, conditions in which the enzyme is readily inactivated, required the stabilization of the soluble enzyme. This was attained by the addition of 25% glycerol. Using this additive, immobilization on glyoxyl-agarose beads proceeded very quickly with good ...
Tópico(s): Electrochemical sensors and biosensors
2009 - Elsevier BV | Journal of Molecular Catalysis B Enzymatic
Produção Nacional
Revisado por pares
Giandra Volpato, Rafael C. Rodrigues, Júlio Xandro Heck, Marco Antônio Záchia Ayub,
Tópico(s): Innovative Microfluidic and Catalytic Techniques Innovation
2009 - Springer Science+Business Media | Biotechnology and Bioprocess Engineering
Produção Nacional
Revisado por pares
Júlio Xandro Heck, Plinho Francisco Hertz, Marco Antônio Záchia Ayub,
In Brazil, a large amount of a fibrous residue is generated as result of soybean (Glycine max) protein production. This material, which is rich in hemicellulose and cellulose, can be used in solid state cultivations for the production of valuable metabolites and enzymes. In this work, we studied the bioconversion of this residue by bacteria strains isolated from water and soil collected in the Amazon region. Five strains among 87 isolated bacteria selected for their ability to produce either celullases ...
Tópico(s): Enzyme Catalysis and Immobilization
2002 - Springer Nature | Brazilian Journal of Microbiology
Produção Nacional
Revisado por pares
Giandra Volpato, Rafael C. Rodrigues, Júlio Xandro Heck, Marco Antônio Záchia Ayub,
Abstract BACKGROUND: In this work we used Plackett–Burman statistical design and central composite design in order to optimize culture conditions for lipase production by Staphylococcus caseolyticus strain EX17 growing on raw glycerol, which was obtained as a by‐product of the enzymatic synthesis of biodiesel. The stability of lipase was verified over several organic solvents, such as methanol, ethanol and n ‐hexane. RESULTS: Optimal culture conditions for lipase production were found to be 36 °C, ...
Tópico(s): Biofuel production and bioconversion
2008 - Wiley | Journal of Chemical Technology & Biotechnology
Produção Nacional
Revisado por pares
Júlio Xandro Heck, Luís Henrique de Barros Soares, Plinho Francisco Hertz, Marco Antônio Záchia Ayub,
Xylanase from Amazon isolate Bacillus circulans BL53 grown on solid-state cultivation was purified to apparent homogeneity by ammonium sulphate fractioning, cation-exchange and gel filtration chromatography. A purification factor of 428-fold was achieved, with the purified enzyme presenting a specific activity of about 37 U mg−1 protein. The xylanase molecular weight was calculated as 38 kDa by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and its isoeletric point was determined ...
Tópico(s): Enzyme Catalysis and Immobilization
2006 - Elsevier BV | Biochemical Engineering Journal
Produção Nacional
Revisado por pares
Júlio Xandro Heck, Simone Hickmann Flôres, Plinho Francisco Hertz, Marco Antônio Záchia Ayub,
A 22 factorial design was performed to find the best conditions of pH and temperature for xylanolytic activity of Bacillus circulans BL53 isolated from the Amazon environment. Solid-state cultivation was carried out on an inexpensive, abundant agro-industrial soybean residue. The central composite design (CCD) used for the analysis of treatment combinations showed that a second-order polynomial regression model was in good agreement with experimental results, with R2 = 0.9369 (P < 0.05). The maximum activity ...
Tópico(s): Enzyme Catalysis and Immobilization
2005 - Elsevier BV | Bioresource Technology
Produção Nacional
Revisado por pares
Júlio Xandro Heck, Plinho Francisco Hertz, Marco Antônio Záchia Ayub,
The extraction optimization of xylanases produced in solid-state cultivations of a strain of Bacillus circulans recently isolated from Amazon basin was examined, with the purpose of reducing enzyme losses in order to obtain crude extracts as concentrated as possible. Substrate for growth and enzyme production was an industrial fibrous soy residue, rich in protein and hemicellulose. Several extraction solvents and temperatures were tested. A 23 factorial design was performed to find the best conditions ...
Tópico(s): Enzyme Catalysis and Immobilization
2005 - Elsevier BV | Process Biochemistry
Produção Nacional
Revisado por pares
Júlio Xandro Heck, Luís Henrique de Barros Soares, Marco Antônio Záchia Ayub,
A 23 central composite design (CCD) was applied to determine the optimal conditions of cultivation time, aeration and temperature to xylanase and mannanase production by Bacillus circulans BL53, a strain isolated from the Amazonian environment. The results suggest that xylanase production by B. coagulans BL53 is higher at a moderate cultivation aeration and at low temperatures and following CCD modeled conditions, we were able to increase 2.5-fold enzyme activities previously obtained and published ...
Tópico(s): Enzyme Catalysis and Immobilization
2005 - Elsevier BV | Enzyme and Microbial Technology
Produção Nacional
Revisado por pares
Júlio Xandro Heck, Simone Hickmann Flôres, Plinho Francisco Hertz, Marco Antônio Záchia Ayub,
A 22 factorial design was performed to find the best pH and temperature for xylonolytic activity of cellulase-free Bacillus coagulans isolated from the Amazon environment. Solid-state cultivation was carried out on an inexpensive and abundant agro-industrial soybean residue. The central composite design (CCD) used for the analysis of treatment combinations showed that a second order polynomial regression model was in good agreement with experimental results, with R2=0.8319 (P<0.05). The maximum activity ...
Tópico(s): Enzyme Catalysis and Immobilization
2004 - Elsevier BV | Process Biochemistry
Rosa Montes, Josu Aguirre, Xandro Vidal, Rosario Rodil, R. Cela, José Benito Quintana,
The presence of persistent and mobile organic contaminants (PMOC) in aquatic environments is a matter of high concern due to their capability of crossing through natural and anthropogenic barriers, even reaching drinking water. Most analytical methods rely on reversed-phase liquid chromatography (RPLC), which is quite limited for the detection of very polar chemicals. Thus, many of these PMOCs may have not been recognized as water pollutants yet, due to the lack of analytical methods capable to detect ...
Tópico(s): Analytical chemistry methods development
2017 - American Chemical Society | Environmental Science & Technology
Xandro Vidal, José L. Mascareñas, Moisés Gulı́as,
Benzyl and allyltriflamides can engage in Pd-catalyzed oxidative (4+2) annulations with allenes, to produce highly valuable tetrahydroisoquinoline or dihydropyridine skeletons. The reaction is especially efficient when carried out in the presence of designed N-protected amino acids as metal ligands. More importantly, using this type of chiral ligands, it is possible to perform desymmetrizing, annulative C–H activations of prochiral diarylmethylphenyl amides, and thus obtain the corresponding isoquinolines ...
Tópico(s): Synthesis and Catalytic Reactions
2019 - American Chemical Society | Journal of the American Chemical Society
Xandro Vidal, José L. Mascareñas, Moisés Gulı́as,
Cycloaddition reactions are among the most practical strategies to assemble cyclic products; however, they usually require the presence of reactive functional groups in the reactants. Here, we report a palladium-catalyzed formal (4 + 2) cycloaddition that involves the activation of C(sp3)–H bonds and provides a direct, unconventional entry to tetrahydroquinoline skeletons. The reaction utilizes amidotolyl precursors and allenes as annulation partners, and is catalyzed by Pd(II) precursors in combination ...
Tópico(s): Cyclopropane Reaction Mechanisms
2021 - American Chemical Society | Organic Letters
José Manuel González, Xandro Vidal, Manuel Á. Ortuño, José L. Mascareñas, Moisés Gulı́as,
We report the first examples of the use of a new class of ligands (NOBINAc) for performing asymmetric C-H activations using palladium catalysts. These ligands combine the axial chirality of binaphthyl scaffolds with the bifunctional and bidentate coordination properties of mono-N-protected amino acids (MPAAs), which are well-known to favor Pd-promoted C-H activations via concerted metalation-deprotonation mechanisms. We demonstrate that our new ligands enable substantially higher enantioselectivities ...
Tópico(s): Cyclopropane Reaction Mechanisms
2022 - American Chemical Society | Journal of the American Chemical Society
Produção Nacional
Revisado por pares
Daniele Misturini Rossi, Simone Hickmann Flôres, Júlio Xandro Heck, Marco Antônio Záchia Ayub,
The use of mechanically deboned poultry meat (MDPM) as a source of raw protein for the enzymatic preparation of hydrolysates was investigated using commercial proteases Alcalase and Flavourzyme. Hydrolysis conditions were optimized by response surface methodology, and the influence of temperature, pH, and enzyme concentration were evaluated to determine the hydrolysis index. For Alcalase, optimal values of temperature, pH, and enzyme concentration were found to be 50°C, 7.5%, and 2.5%, respectively, ...
Tópico(s): Proteins in Food Systems
2009 - Taylor & Francis | Food Biotechnology
Produção Nacional
Revisado por pares
Giandra Volpato, Marco Filice, Blanca de las Rivas, Rafael C. Rodrigues, Júlio Xandro Heck, Roberto Fernandéz‐Lafuente, José M. Guisán, César Mateo, Marco Antônio Záchia Ayub,
Staphylococcus warneri strain EX17 produces three lipases with different molecular weights of 28, 30, and 45 kDa. The 45 kDa fraction (SWL-45) has been purified from crude protein extracts by one chromatographic step based on the selective adsorption of this lipase by interfacial activation on different hydrophobic supports at low ionic strength. The adsorption of SWL-45 on octyl-Sepharose increased the enzyme activity by 60%, but the other lipases were also adsorbed on this support. Using butyl- ...
Tópico(s): Microbial Metabolic Engineering and Bioproduction
2011 - American Chemical Society | Biotechnology Progress
Produção Nacional
Revisado por pares
Cláucia Fernanda Volken de Souza, Débora Jung Luvizetto Faccin, Omar Mertins, Júlio Xandro Heck, Nádya Pesce da Silveira, Argimiro R. Secchi, Marco Antônio Záchia Ayub,
Abstract BACKGROUND: This paper describes the modeling of the kinetics of thermal inactivation of transglutaminase (TGase) from a newly isolated Bacillus circulans BL32, isolated from the Amazon environment. The purified enzyme was incubated at temperatures ranging from 30 to 70 °C and values of the thermodynamic inactivation parameters, such as activation energy (Δ E ), activation enthalpy (Δ H ), activation entropy (Δ S ), and free energy (Δ G ) for thermal inactivation, were calculated. RESULTS: The kinetics ...
Tópico(s): Proteins in Food Systems
2009 - Wiley | Journal of Chemical Technology & Biotechnology
Rafael Reisenhofer, Xandro Bayer, Nikolaus Hautsch,
Despite the impressive success of deep neural networks in many application areas, neural network models have so far not been widely adopted in the context of volatility forecasting. In this work, we aim to bridge the conceptual gap between established time series approaches, such as the Heterogeneous Autoregressive (HAR) model (Corsi, 2009), and state-of-the-art deep neural network models. The newly introduced HARNet is based on a hierarchy of dilated convolutional layers, which facilitates an exponential ...
Tópico(s): Market Dynamics and Volatility
2022 - RELX Group (Netherlands) | SSRN Electronic Journal
Produção Nacional
Revisado por pares
Cláucia Fernanda Volken de Souza, Rafael C. Rodrigues, Júlio Xandro Heck, Marco Antônio Záchia Ayub,
Abstract BACKGROUND: This paper reports investigations of the extraction of transglutaminase (TGase) produced by Bacillus circulans BL32 on solid‐state cultivation in order to obtain a crude extract with the highest possible specific activity. The optimization of downstream processing parameters for the effective recovery of the enzyme was carried out using response surface methodology based on the central composite rotatable design (CCRD) to reduce losses in the cultivated solids and to obtain a ...
Tópico(s): Enzyme Production and Characterization
2008 - Wiley | Journal of Chemical Technology & Biotechnology
Produção Nacional
Revisado por pares
Róber Bachinski, Thales de Astrogildo e Tréz, Gutemberg Gomes Alves, Rita de Cássia Maria Garcia, Simone Tostes de Oliveira, Luciano da Silva Alonso, Júlio Xandro Heck, Claudia M.C. Dias, João Moreira Costa Neto, Alexandro Aluísio Rocha, Valeska Regina Reque Ruiz, Rita Leal Paixão,
Humane education and the debate on alternatives to harmful animal use for training is a relatively recent issue in Brazil. While animal use in secondary education has been illegal since the late 1970s, animal use in higher science education is widespread. However, alternatives to animal experiments in research and testing have recently received attention from the Government, especially after the first legislation on animal experiments was passed, in 2008. This article proposes that higher science ...
Tópico(s): Science Education and Perceptions
2015 - SAGE Publishing | Alternatives to Laboratory Animals
Guillermo Díaz‐Agras, Juan Moreira, Ramiro Tato, Xandro García Regueira, Victoriano Urgorri,
Tópico(s): Marine Ecology and Invasive Species
2010 - Springer Science+Business Media | Thalassas An International Journal of Marine Sciences
Tópico(s): Digital Games and Media
2004 - Belltown Media | Linux journal
2004 - Belltown Media | Linux journal
Xandro García Regueira, Ramiro Tato, Juan Moreira, Victoriano Urgorri,
Tópico(s): Isotope Analysis in Ecology
2010 - Springer Science+Business Media | Thalassas An International Journal of Marine Sciences
... Aires 1940), 65. 7. Ibid., 68–70. Mauricio Xandró, in Blasco Ibáñez (Madrid 1971), 29, distorts Blasco' ...
Tópico(s): Comparative Literary Analysis and Criticism
1976 - Liverpool University Press | Bulletin of Hispanic Studies
Produção Nacional
... do Nascimento (Instituto Federal de Brasília, Brasil)Júlio Xandro Heck (Instituto Federal do Rio Grande do Sul, ...
2017 - Associação Sul-Rio-Grandense de Pesquisadores em História da Educação (ASPHE) | ScientiaTec
Mercy Liliana Borbón Hoyos, Mario Heimer Flórez Guzmán, Rodrigo Alberto Plazas Estepa,
... grafología descriptiva y emocional de Max Pulver, Mauricio Xandró y Augusto Vels, los cuales afirman que la ...
Tópico(s): Criminal Justice and Penology
2018 - Universidad Santo Tomás | IUSTA
PHOTO: XANDRO VANDEWALLE/UNSPLASH editor’s pick Sigrid Nunez The Friend Riverhead Books D o the books we need ...
Tópico(s): Cultural Studies and Interdisciplinary Research
2018 - University of Oklahoma | World Literature Today
Marta Cernuda-Aspe, Francisco Pérez Fernández,
... de extroversión mediante la prueba proyectiva grafológica de Xandró, y la medición cuantitativa propuesta por el modelo ...
Tópico(s): Stress and Burnout Research
2018 - | Edupsykhé Revista de Psicología y Educación
PHOTO: XANDRO VANDEWALLE/UNSPLASH editor's pick Sigrid Nunez The Friend Riverhead Books D o the books we need ...
Tópico(s): Cultural Studies and Interdisciplinary Research
2019 - University of Oklahoma | World Literature Today