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dc.contributor.authorNeves, Valdir Augusto-
dc.contributor.authorda Silva, Maraiza Aparecida-
dc.identifier.citationJournal of Agricultural and Food Chemistry. Washington: Amer Chemical Soc, v. 55, n. 6, p. 2424-2430, 2007.-
dc.description.abstractPolyphenol oxidase (E.C. (PPO) extracted from yacon roots (Smallanthus sonchifolius) was partially purified by ammonium sulfate fractionation and separation on Sephadex G-100. The enzyme had a molecular weight of 45 490 +/- 3500 da and K-m values of 0.23, 1.14, 1.34, and 5.0 mM for the substrates caffeic acid, chlorogenic acid, 4-methylcatechol, and catechol, respectively. When assayed with resorcinol, DL-DOPA, pyrogallol, protocatechuic, p-coumaric, ferulic, and cinnamic acids, catechin, and quercetin, the PPO showed no activity. The optimum pH varied from 5.0 to 6.6, depending on substrate. PPO activity was inhibited by various phenolic and nonphenolic compounds. p-Coumaric and cinnamic acids showed competitive inhibition, with K-i values of 0.017 and 0.011 mM, respectively, using chlorogenic acid as substrate. Heat inactivation from 60 to 90 degrees C showed the enzyme to be relatively stable at 60-70 degrees C, with progressive inactivation when incubated at 80 and 90 degrees C. The E-a (apparent activation energy) for inactivation was 93.69 kJ mol(-1). Sucrose, maltose, glucose, fructose, and trehalose at high concentrations appeared to protect yacon PPO against thermal inactivation at 75 and 80 degrees C.en
dc.publisherAmer Chemical Soc-
dc.sourceWeb of Science-
dc.subjectyacon rootspt
dc.subjectSmallanthus sonchifoliuspt
dc.subjectpolyphenol oxidasept
dc.subjectthermal inactivationpt
dc.subjectsugar protectionpt
dc.titlePolyphenol oxidase from yacon roots (Smallanthus sonchifolius)en
dc.contributor.institutionUniversidade Estadual Paulista (UNESP)-
dc.description.affiliationUniv Estadual Paulista, UNESP, FCF Ar, Dept Alimentos & Nutr,Lab Bioquim Alimentos, BR-14801902 Araraquara, SP, Brazil-
dc.description.affiliationUnespUniv Estadual Paulista, UNESP, FCF Ar, Dept Alimentos & Nutr,Lab Bioquim Alimentos, BR-14801902 Araraquara, SP, Brazil-
dc.rights.accessRightsAcesso restrito-
dc.relation.ispartofJournal of Agricultural and Food Chemistry-
Appears in Collections:Artigos, TCCs, Teses e Dissertações da Unesp

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