title: Partial purification and characterization of polyphenol oxidase from persimmon.
abstract: Activity of polyphenol oxidase (PPO) from "Rojo Brillante" persimmon (Diospyros kaki L.) fruits was characterized. Crude extracts were used for characterization of enzyme activity and stability at different temperatures (60, 70 and 80 °C), pHs (from 3.5 to 7.5) and substrate concentrations (catechol from 0 to 0.5M). Maximum enzyme activity was reached at pH 5.5 and 55 °C. Enzyme stability was higher than PPO activities found in other natural sources, since above pH 5.5 the minimum time needed to achieve an enzyme inactivation of 90% was 70 min at 80 °C. However, at pH 4.0 the enzyme stability decreased, reaching inactivation levels above 90% after 10 min even at 60 °C. Thus it was concluded that acidification can circumvent browning problems caused by PPO activity. Moreover, polyacrylamide gel electrophoresis of the enriched extract revealed the presence of at least four bands with strong oxidase activity, suggesting the existence of different PPO isoforms.
authors.affiliation: Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Avda. Agustín Escardino, 7, 46980 Paterna, Valencia, Spain. Electronic address: jlnavarro@iata.csic.es.
authors.forename: José L
authors.initials: JL
authors.lastname: Navarro
authors.affiliation: Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Avda. Agustín Escardino, 7, 46980 Paterna, Valencia, Spain.
authors.forename: Amparo
authors.initials: A
authors.lastname: Tárrega
authors.affiliation: Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Avda. Agustín Escardino, 7, 46980 Paterna, Valencia, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Sentandreu
authors.affiliation: Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Avda. Agustín Escardino, 7, 46980 Paterna, Valencia, Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Sentandreu
mesh_terms: D004156:Catechol Oxidase / Q000378:metabolism*; D029788:Diospyros / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods*; D005638:Fruit / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*
chemical_list: D010636:Phenols; D004156:Catechol Oxidase
keywords: Diospyros kaki; Enzyme isoforms; Enzyme purification; Persimmons; Polyacrylamide gel electrophoresis; Polyphenol oxidase characterization