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

Abstract

Characterization of polyphenol oxidase during three ripening stages of an eggplant (Solanum melongena L.) fruit: a local type in northeast Anatolia[Patlıcan (Solanum melongena L.) meyvesinin polifenol oksidazının üç olgunlaşma safhası boyunca karakterizasyonu: Doğu Anadolu' da yerel bir tip] ABSTRACT Objective: A relatively new local type of eggplant, Solanum melongena L. 'Kadife' is widely consumed in Turkey because of its economic availability and good nutritional qualities. However, the high polyphenol content of eggplant renders it susceptible to unattractive oxidative browning catalyzed by polyphenol oxides (PPOs). Therefore, the main aim of this study was to characterize PPO in this eggplant cultivar at three stages of its development. Methods: In this study, we determined substrate specificity, optimum pH and temperature, and optimum substrate concentration of the partial purified eggplant fruits PPO during ripening. Results: L-DOPA was proved to be the preferred PPO substrate in all three stages of ripening. Optimum activity was observed at pH 7.0 for PPO in extracts of ripening and overly-ripe eggplant, while activity in extracts of immature eggplant exhibited a broad pH optimum between, pH 5.0 and 7.0. In general, at all ripening stages, PPO was most active at 30°C and was most sensitive to inhibition by sodium metabisulphite and ascorbic acid. The metal ions (Hg ÖZETAmaç: Kısmen yeni bir yerel tip patlıcan çeşidi Solanum melongena L. 'Kadife', ekonomik uygunluğu ve iyi besin kalitesinden dolayı Türkiye'de yaygın olarak tüketilir. Bununla birlikte, patlıcanın yüksek polifenol içeriği, bu meyveyi polifenol oksidaz (PFO) tarafından katalizlenen istenmeyen oksidatif esmerleşmeye karşı duyarlı kılar. Dolayısıyla, bu çalışmanın temel amacı, gelişiminin üç safhasında bu patlıcan kültivarındaki PFO'yu karakterize etmektir. Metod: Bu çalışmada, olgunlaşma boyunca patlıcan meyvelerinden elde edilen kısmi saflaştı-rılmış PFO'nun substrat özgünlüğünü, optimum pH ve sıcaklığını, ve optimum substrat konsantrasyonunu belirledik. Bulgular: Olgunlaşmanın her üç safhasında, L-DOPA'nın tercih edilen PFO substratı olduğu ortaya konuldu. Olgunlaşmamış patlıcan özütlerinde optimum pH 5.0 ile 7.0 arasında geniş bir aktivite gösterirken olgun ve aşırı olgun patlıcan özütlerindeki PFO aktivitesi için optimum pH'nın 7.0 olduğu gözlendi. Genel olarak, tüm olgunlaşma safhalarında, PFO, 30°C'de en aktiftir ve inhibitör olarak sodyum metabisülfit ve askorbik aside oldukça duyarlıdır. 24, 2015] been named as "Kadife" for years by the local growers in northeast Anatolia (Turkey), at three different stages of maturation. The plant, with its light purple and white striped fruit is widely cultivated and consumed in Trabzon and elsewhere in the region compared to other species. Specifically, our aim was to determine PPO-specific activity from eggplants at time of flowering and at intervals of 2 weeks thereafter. In addition, we studied the effects of pH and temperature, as well as the effects of a variety of inhibitors and metal io...

A catecholase fromLaccaria laccataa wild edible mushroom and its catalytic efficiency in organic media

“…K m values for other substrates smoothly increased but V max decreased. K m values reported in previous studies in literature for mushroom (Colak et al, ; Espin, Leeuwen & Wichers, ; Kolcuoğlu et al, ) and other organisms (Liu et al, ; Torun et al, ) showed that Lac PPO has great substrate affinity. For most biotechnologically important enzymes, K m values varied within the range of 10 −1 –10 −5 M (Fullbrook, ).…”

“…K m values for other substrates smoothly increased but V max decreased. K m values reported in previous studies in literature for mushroom Espin, Leeuwen & Wichers, 1999;Kolcuoğlu et al, 2007) and other organisms (Liu et al, 2013;Torun et al, 2015) showed that…”

“…The acidic and neutral pH optima were reported in the literature for catecholase activity in the presence of different diphenolic substrates. Macrolepiota gracilenta showed optimum pH at 5.0 (Kolcuoğlu, ), Macrolepiota mastoidea between pH 4.0 and 5.0 (Kolcuoğlu et al, ), Hypholoma fasciculare at pH 7.0 (Colak et al, ), Malus domestica at pH 6.5 (Deirdre et al, ), Lonicera japonica at pH 7.5 (Liu, et al, ), and Solanum melongena at pH 7.0 (Torun et al, ).…”

“…There is a dearth of literature available on PPOs' characteristics, especially for mushroom PPOs, in the presence of DHPPA and L-DOPA substrates. , Malus domestica at pH 6.5 (Deirdre et al, 2006), Lonicera japonica at pH 7.5 (Liu, et al, 2013), and Solanum melongena at pH 7.0 (Torun et al, 2015).…”

Evaluating the Phoenix dactylifera L. Biochemical Changes Associated With Its Maturation

“…This catalytic characteristic assists in the fruit maturation. Similar is the effect produced in the amylase, pectinase, and cellulase reactions, which are often used for the conversion of polysaccharides into oligo and monosaccharides (Torun et al, 2015).…”