Catechol oxidases, endogenous substrates and browning in developing apples

Harel, E.; Mayer, Alfred M.; Shain, Y.

doi:10.1002/jsfa.2740170901

Cited by 59 publications

(27 citation statements)

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“…4 The amount of odiphenols which can serve as substrates for catechol oxidase often declines during fruit development. [8][9][10] The olive undergoes considerable changes in fruit texture and chemical composition during ripening and subsequent transition to the black friiit.ll We followed the level, properties and location of catechol oxidase and the content of o-diphenols during fruit development in an attempt to understand the factors which contribute to the browning of olives. Some properties of the enzyme from green and black olives were compared with those of the enzyme purified from an acetone powder of green olives.12…”

Section: Introductionmentioning

confidence: 99%

Olive catechol oxidase ‐ changes during fruit development

et al. 1977

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Changes were recorded in the subcellular location of catechol oxidase. In the green olive the enzyme is tightly bound to the chloroplast whereas in the black fruit it is essentially soluble. During fruit development, enzyme activity per fruit declines while the o-diphenolic content rises steadily. Some properties of catechol oxidase from green and black olives are compared with those reported for the partially purified enzyme prepared from the green fruit.

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Section: Introductionmentioning

confidence: 99%

Olive catechol oxidase ‐ changes during fruit development

et al. 1977

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“…The rates of formation of phenolics and of catechol oxidase are quite different and peak at different times. Such differences have frequently been reported in plant tissues, for example in apples and peaches (3,4).…”

Section: Resultsmentioning

confidence: 79%

Changes in Catechol Oxidase and Permeability to Water in Seed Coats of Pisum elatius during Seed Development and Maturation

Marbach¹,

Mayer²

1975

Plant Physiol.

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In the developing seed coat of Pisum elatius, o-dihydroxyphenols are present in appreciable amounts at all stages of development. However, catechol oxidase activity rises sharply during the later stages of development, shows a further abrupt rise during dehydration of the seed coat, and then decreases. It is suggested that a tanning reaction is induced by the contact of enzyme with its substrate while cell membranes are ruptured, and that this reaction renders the seed coats impermeable. The entire chain of events does not occur in Pisum sativum which has permeable seed coats.The germination of many species of seeds, especially of the Leguminoseae, is controlled by "hard seededness" (10,11,13). Conditions during seed storage (7) and environmental conditions during seed development and maturation may affect "hard seededness" (1) and permeability (7). For some seeds of the Leguminoseae it has been shown that there is a connection between the color of the seed coats and their permeability to water (1, 9).In a previous paper (9) we hypothesized that during dehydration of seeds, oxidation of phenolic compounds in seed coats catalyzed by catechol oxidase might render the seed coat impermeable to water. In order to test this hypothesis, we followed the content of catechol oxidase activity and of phenolic compounds during development and maturation of pea seeds. We have used wild peas, Pisum elatius, which have an impermeable seed coat and cultivated peas P. sativum, which have a permeable seed coat. We will show that changes in seed coat permeability are correlated with a change in the level of catechol oxidase, and suggest a mechanism by which permeability is changed. MATERIALS AND METHODSSeeds of Pisum sativum var. Alaska and Pisum elatius were grown outdoors in Jerusalem. Pods and seeds were collected at different stages of seed development and maturation as described in Tables I and II. Samples of seed coats, cotyledons, and whole seeds were taken for determination of fresh and dry weight (10 samples of 10 seeds were taken for each determination).Catechol oxidase activity was determined in homogenates of the seed coats, cotyledons, and entire seed. Usually, 3 g of seed coats or 5 g of cotyledons or whole seeds were used for preparing the homogenates which were prepared as previously described (8). The homogenate was fractionated by centrifugation to give a particulate-20,000g precipitate-and a supernatant fraction. The precipitate was resuspended in the same buffer used for preparing the homogenate, using 1 ml buffer per gram original fresh weight.Catechol oxidase activity was determined according to Harel and Mayer (2), using 5 nm 4-methylcatechol as substrate at pH 7.3. Only the activity of the particulate fraction at pH 7.3 is given, because previous results (8) showed that activity in the soluble cell fraction is negligible. This result was reconfirmed in the present investigation.The o-diphenol content of the tissue was measured according to Mapson et al. (8) using the sodium molybdate method. The tot...

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“…Algunos tratamientos pueden alterar la estructura y la conformación de la enzima provocando el paso de su forma inactiva o latente a su forma activa (Kenten, 1958), si bien la recuperación de la enzima nativa latente es posible mediante el uso de detergentes no iónicos suaves (Sánchez-Ferrer et al,, 1994). Esta solubilización también tiene lugar en condiciones naturales, como son la maduración de las frutas y el envejecimiento de los tejidos (Harel et al, 1966;Kidron et al, 1978).…”

Section: Ciencia Y Tecnología 2014 7(1):23-31unclassified

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

Carriel

Agnieszka-Obrebska

Bru-Martínez

et al. 2014

CyT

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. Quito km, 1.5 vía a Santo Domingo de los Tsáchilas. EC-120501. Quevedo, Ecuador. rpico@uteq.edu.ec resumen L as polifenol oxidasas (PPOs) son enzimas ubicuas que catalizan la reacción dependiente de oxígeno que transforma o-difenoles en o-quinonas. Estas quinonas son reactivas y capaces de modificar covalentemente un amplio abanico de especies nucleófilas, del interior de las células, que conduce a la formación de polímeros marrones, conocido como pardeamiento enzimático. El fenómeno de pardeamiento durante el crecimiento, recogida, almacenamiento y procesado de frutos y vegetales, es un problema de primera magnitud en la industria agroalimentaria y se reconoce como una de las principales causas de pérdidas de calidad y valor comercial. Produce cambios importantes tanto en la apariencia como en las propiedades organolépticas de frutos y vegetales comestibles, además suele ir asociado al desprendimiento de olores y efectos negativos sobre el valor nutricional. Aunque las PPOs se han descrito en diversos tejidos de plantas como raíces, semillas, hojas y frutos, el control de este fenómeno requiere un conocimiento bioquímico del tipo de sustratos fenólicos presentes en cada planta, el nivel de compuestos reductores, el nivel de accesibilidad del O 2 , de la naturaleza de los diferentes compuestos oxidables y de la polimerización y degradación de las o-quinonas. En este trabajo se presenta una revisión del efecto bioquímico, distribución, localización y posibles inhibidores de las PPOs en frutos y vegetales usados como alimento.Palabras clave: Polifenol oxidasas, pardeamiento enzimático, frutos y vegetales. abstract P olyphenol oxidases (PPOs) are ubiquitous enzymes that catalyze the oxygen-dependent reaction that transforms o-diphenols to o-quinones. These quinones are reactive and capable of covalently modifying a wide variety of nucleophilic species into cells leading to the formation of brown polymers, known as enzymatic browning. The phenomenon of browning during growth, collection, storage and processing of fruits and vegetables, is a major problem in the food industry and is recognized as one of the leading causes of commercial value and quality loss, since it produces important changes in the appearance and organoleptic properties of edible fruits and vegetables, and it is often associated to the release of odors and negative effects on nutritional value. Although PPOs have been described in various plant tissues such as roots, sedes, leaves and fruits, the control of this phenomenon requires biochemical knowledge of the type of phenolic substrates present in each plant, the level of reducing compounds, the level of O 2 accessibility, of the nature of the various oxidizable compounds and, finally, o-quinones polymerization and degradation. This paper present a review of the biochemical effect, distribution, location and potential inhitors of PPOs in fruits used for food.

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Catechol oxidases, endogenous substrates and browning in developing apples

Cited by 59 publications

References 19 publications

Olive catechol oxidase ‐ changes during fruit development

Olive catechol oxidase ‐ changes during fruit development

Changes in Catechol Oxidase and Permeability to Water in Seed Coats of Pisum elatius during Seed Development and Maturation

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

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