ศูนย์นวัตกรรมเทคโนโลยีหลังการเก็บเกี่ยว

Partial purification and some properties of polyphenol oxidase extracted from litchi fruit pericarp

Yue-Ming Jiang, Giora Zauberman and Yoram Fuchs

Postharvest Biology and Technology Vol: 10 Issue: 3 Pages: 221-228.

1997

บทคัดย่อ

Litchi (Litchi chinensis Sonn.) fruit peel polyphenol oxidase (PPO) was partially purified 21 fold by ammonium sulfate fractionation and gel filtration. Pyrogallol, catechol, and 4-methylcatechol were good substrates for the enzyme; with no activity observed with chlorogenic acid, p-cresol, resorcinol, or tyrosine. The optimal pH for PPO activity was 7.0 with 4-methylcatechol, with the enzyme being most stable at pH 7.4. The enzyme was relatively temperature stable with maximum activity at 70°C and requiring a little less than 10 min at 90°C for 50% loss of activity. The K_m and V_max for the enzyme, with 4-methylcatechol, were 10 mM and 1.47 × 10⁴ units/min per mg protein, respectively. The enzyme was not activated by SDS. Reduced glutathione,-cysteine, tropolone, thiourea, FeSO₄, and SnCl₂ markedly inhibited PPO activity, whereas MnSO₄ and CaCl₂ enhanced PPO activity. Data obtained in this study might help to better understand and control commercially, litchi fruit peel browning.