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Provedor de dados:  BABT
País:  Brazil
Título:  Ionically Bound Peroxidase from Peach Fruit
Autores:  Neves,Valdir Augusto
Data:  2002-03-01
Ano:  2002
Palavras-chave:  Peach peroxidases
Heat stability
Resumo:  Soluble, ionically bound peroxidase (POD) and polyphenoloxidase (PPO) were extracted from the pulp of peach fruit during ripening at 20°C. Ionically bound form was purified 6.1-fold by DEAE-cellulose and Sephadex G-100 chromatography. The purified enzyme showed only one peak of activity on Sephadex G-100 and PAGE revealed that the enzyme was purified by the procedures adopted. The purified enzyme showed a molecular weight of 29000 Da, maximum activity at pH 5.0 and at 40ºC. The calculated apparent activation energy (Ea) for the reaction was10.04 kcal/mol. The enzyme was heat-labile in the temperature range of 60 to 75ºC with a fast inactivation at 75ºC. Measurement of residual activity showed a stabilizing effect of sucrose at various temperature/sugar concentrations (0, 10, 20 %, w/w), with an activation energy (Ea) for inactivation increasing with sucrose concentration from 0 to 20% (w/w). The Km and Vmax values were 9.35 and 15.38 mM for 0-dianisidine and H2O2, respectively. The bound enzyme was inhibited competitively by ferulic, caffeic and protocatechuic acids with different values of Ki,. L-cysteine, p-coumaric and indolacetic acid and Fe++ also inhibited the enzyme but at a lower grade. N-ethylmaleimide and p-CMB were not effective to inhibit the enzyme demonstrating the non-essentiality of SH groups.
Tipo:  Info:eu-repo/semantics/article
Idioma:  Inglês
Editor:  Instituto de Tecnologia do Paraná - Tecpar
Relação:  10.1590/S1516-89132002000100002
Formato:  text/html
Fonte:  Brazilian Archives of Biology and Technology v.45 n.1 2002
Direitos:  info:eu-repo/semantics/openAccess

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