DOMAT ZEYTİNİ POLİFENOL OKSİDAZININ BİYOKİMYASAL ÖZELLİKLERİNİN BELİRLENMESİ

Abstract

Enzymatic browning of damaged tissues of fruits and vegetables occurs from the oxidation of phenolic compounds and contributes significantly to quality loss. The primary enzim responsible for the browning reaction is polyphenol oxidase (PPO). PPO from Domat olives was extracted and purified through (NH4)2SO4 precipitation, dialysis and ion exchange chromatography. Optimum pH and temperature for olive PPO were found to be 4.5 and 30 °C, respectively, using 4-methyl catechol as substrate. Km and Vmax values for olive PPO using 4-methyl catechol as substrate were found to be 14.52 mM (r2= 0.985) and 1.78 Abs/min, respectively. Of the inhibitors tested, the most potent inhibitors were L-cysteine and sodium disulfite. The Z and Ea values obtained in this study were 18.6 °C (r2 = 0.953) and 121.0 kj/mol (r2= 0.950), respectively

Özet

Zarar görmüş meye ve sebzelerdeki enzimatik esmerleflme fenolik bilefliklerin oksidasyonu sonucu meydana gelir ve önemli kalite kay›plar›na neden olur. Esmerleflme reaksiyonuna neden olan en önemli enzim polifenol oksidaz (PFO)’d›r. Domat zeytininden polifenol oksidaz enzimi ekstrakte edilmifl ve amonyum sülfat çökeltmesi, dializ ve iyon de¤iflim kromatografisi ile saflaflt›r›lm›flt›r. Zeytin PFO’sunun optimum pH ve s›cakl›¤› s›ras›yla 4-metil kateflol substrat› kullan›larak 4.5 ve 30 °C bulunmufltur. Zeytin PFO’su Km ve Vmax de¤erleri s›ras›yla 4-metil kateflol substrat› kullan›larak 14.52 mM (r2= 0.985) ve 1.78 Abs/dak bulunmufltur. Test edilmifl inhibitörlerin en etkili olanlar› sistein ve sodyum disülfittir. Bu çal›flmada elde edilmifl Z ve Ea de¤erleri s›ras›yla 18.6 °C (r2 = 0.953) ve 121.0 kj/mol (r2= 0.950) bulunmufltur.