Extraction, Partial Purification and Characterisation of Polyphenol Oxidase from Tea Leaf (Camellia sinensis) (in English)

Öz

Polyphenol oxidase (PPO) from tea leaves was extracted and partially purified through (NH4)2SO4 precipitation, dialysis and ion exchange chromatography. Of the substrates tested, 4-methylcatechol was the best substrate for PPO with a Km value of 127.8 mM. The optimum pH for PPO activity was found to be 6.02. The enzyme showed high activity over a broad pH range of 4.03-7.00. The optimum temperature for PPO activity was 30 °C. The enzyme had more than 70% of the maximum activity between 20-80 °C. Energy of activation (Ea) and Z values were found to be 58.301 kJ/mol (r2= 0.961) and 39.68°C (r2= 0.965), respectively. Of the inhibitors tested, L-cysteine was the least potent inhibitor.

Anahtar Kelimeler

• Inhibition, kinetics, purification, polyphenol oxidase, tea, thermal inactivation

Polifenol Oksidazın Çay (Camellia sinensis) Yaprağından Ekstraksiyonu, Kısmi Saflaştırılması ve Karakterizasyonu (İngilizce)

Öz

Polifenol oksidaz (PFO) çay yapraklarından ekstrakte edilip (NH4)2SO4 çökeltmesi, diyaliz ve iyon değişim kromatografisi ile kısmen saflaştırılmıştır. Test edilen substratlardan, 127.8 mM Km değeri ile 4-metilkateşol PFO için en iyi substrat olarak belirlenmiştir. PFO aktivitesi için optimum pH 6.02 olarak saptanmıştır. Enzim, 4.03-7.00 gibi geniş bir pH aralığında aktivite göstermiştir. PFO aktivitesi için optimum sıcaklık 30°C olarak bulunmuştur. 20-80 °C’ler arasında enzim maksimum aktivitesinin %70’den fazlasını korumuştur. Aktivasyon enerjisi (Ea) ve Z değerleri, sırasıyla, 58.301 kJ/mol (r2= 0.961) ve 39.68 °C (rr2= 0.965) olarak bulunmuştur. Test edilen inhibitörlerden L-sisteinin en düşük inhibisyon derecesine sahip olduğu belirlenmiştir.

Anahtar Kelimeler

• Çay, inhibisyon, kinetik, polifenol oksidaz, saflaştırma, termal inaktivasyon

Kaynakça

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