Navegando por Autor "Queiróz, José H. de"

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    Characterization of an exoinulinase produced by Aspergillus terreus CCT 4083 grown on sugar cane bagasse
    (Journal of Agricultural and Food Chemistry, 2010-02-07) Coitinho, Juliana B.; Guimarães, Valéria M.; Almeida, Maíra N. de; Falkoski, Daniel L.; Queiróz, José H. de; Rezende, Sebastião T. de
    Exoinulinase (β- D -fructan fructohydrolase, EC 3.2.1.80) secreted by Aspergillus terreus CCT4083 was obtained using sugar cane bagasse, an agroindustrial residue, as a carbon source. It was further purified from the supernatant culture in a rapid procedure. The enzyme presented 57 kDa on SDS-PAGE and 56 kDa on gel filtration chromatography. Inulin was hydrolyzed by the purified enzyme, yielding D -fructose as the main product. This enzyme showed maximum activity at pH 4.0 and 60 °C and maintained more than 90 and 75% of its original activity at 40 and 50 °C, respectively, after 3.5 h of preincubation. The K M values for inulin, sucrose, and raffinose were 11, 4.20, and 27.89 mM, respectively, and D -fructose was a competitive inhibitor (K i = 47.55 mM). The activation energies for sucrose, raffinose, and inulin were 10.4, 5.61, and 4.44 kcal/mol, respectively. The characteristics of A. terreus exoinulinase were compared to those of inulinases isolated from other organisms. The exoinulinase traits presented especially good thermostability and the ability to produce pure D -fructose, suggesting its application to the production of high-fructose syrup.
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    Potencial da palha de cana-de-açúcar para produção de etanol
    (Química Nova, 2012-01-13) Santos, Fernando A.; Queiróz, José H. de; Colodette, Jorge L.; Fernandes, Sergio A.; Guimarães, Valéria M.; Rezende, Sebastião T.
    Sugarcane straw biomass accounts for 1/3 of the energy potential of sugarcane and represents a rich source of sugars. Studies have been intensified for the use of this biomass along with bagasse for the production of cellulosic ethanol. Development of this technological path will allow for taking full advantage of sugarcane, increasing ethanol production without expanding the area cultivated. However, in order for this technology to be viable certain challenges must be overcome, including establishment of appropriate conditions of pretreatment and hydrolysis of these materials for release of fermentable sugars.