Purification and Properties of Polyphenol Oxidase from Loquat Fruit

Abstract

Polyphenol oxidase (PPO) was purified to homogeneity from loquat (Eriobotrya japonica Lindl. cv. Mogi) fruit. The enzyme was purified 422-fold with a total yield of 35.6%. The molecular weight was estimated to be about 58 000 and 55 000 by SDS-PAGE and FPLC gel filtration chromatography, respectively, indicating that PPO is a monomer. The optimum pH and temperature of the enzyme activity were found to be pH 4.5 and 30 °C, respectively, and the enzyme was stable in the range of pH 4-8. In substrate specificity, a maximum activity was shown with epicatechin, followed by chlorogenic acid, neochlorogenic acid, 4-methylcathechol, and pyrocatechol, and no activity was apparent toward monophenol and p-diphenol. The K m values for chlorogenic and neochlorogenic acids were 0.105 and 0.425 mM, respectively. The enzyme activity was markedly inhibited by sodium ascorbate, diethyldithiocarbamate, metabisulfide, dithiothreitol, mercaptoethanol, NaF, NaN 3 , L-cysteine, and reduced glutathione.

Characterization of polyphenol oxidase during three ripening stages of an eggplant (Solanum melongena L.) fruit: a local type in northeast Anatolia

“…Results show that the most effective inhibitors of PPO activity were sodium metabisulfite and ascorbic acid. These findings are consistent with earlier reports, such as loquat [26], mamey [31] and mulberry [32]. Thiourea and sodium azide were ineffective inhibitors at all stages of eggplant fruit maturation.…”

“…Despite many investigations of the optimum temperatures related to species-and substrate-dependent PPO [11 25], there is little information available on the effect of developmental stage on PPO activity [12]. Optimal temperatures for PPO activity have been reported by other authors [6,20,23,26]. While the values of optimum temperatures related to plant sources range from 18°C to 40°C, there are some exceptional differences in the literature.…”

Distribución, Localización E Inhibidores De Las Polifenol Oxidasas en Frutos Y Vegetales Usados Como Alimento

“…La polifenol oxidasa se ha descrito en diversos tejidos de plantas como raíces (Pérez-Gilabert et al, 2001;Gandía-Herrero et al, 2004), semillas (Paul y Gowda, 2000), hojas (Robinson y Dry, 1992;Sánchez-Ferrer et al, 1993;Chazarra et al, 1996;Mazzafera y Robinson, 2000;Chazarra et al, 2001;Shi et al, 2002) y frutos (Fraignier et al, 1995;Murata et al, 1992;Ding et al, 1998a;Serradell et al, 2000;Casado et al, 2005, Sellés et al, 20062007).…”

Influência de três diferentes embalagens de PVC na vida pós-colheita de nêspera

“…mento, menos no controle, no qual não foi observada variação significativa (Tabela 4), divergindo do comportamento de elevação observado por Ding et al (1998aDing et al ( , 1998bDing et al ( , 1998c. Pode-se inferir que nos frutos sob atmosfera modificada houve, no início do armazenamento, aumento das reações metabólicas, com utilização dos açúcares redutores no processo respiratório, com vista à produção da energia.…”

“…Também se torna evidente uma maior concentração na sacarose nos 20 primeiros dias de armazenamento, decrescendo logo em seguida até os 50 dias. Os resultados obtidos divergem, em parte, dos encontrados por Ding et al (1997aDing et al ( , 1997b e Ding et al (1998bDing et al ( , 1998c, segundo os quais os teores de sacarose decresceram rapidamente no decorrer do armazenamento.…”