甘蔗多酚氧化酶酶学特性及应用研究

Enzymatic characterization and application of a polyphenol oxidase from sugarcane

对甘蔗多酚氧化酶(PPO)进行提取和部分纯化,研究了PPO的酶学特性。结果表明:以邻苯二酚为底物,甘蔗PPO酶促反应米氏常数Km为54.4 mmol/L,米氏方程:V=1250[S]/(54.4+[S])。蔗汁中邻位多酚类物质是甘蔗PPO的最适反应底物。最适反应条件为:pH值6.2,40℃;该酶在pH5.8和温度低于30℃时较稳定。试验了6种甘蔗PPO抑制剂:单独使用柠檬酸、草酸、乙二胺四乙酸(EDTA)对PPO活力抑制效果不明显;70 mg/L亚硫酸氢钠、110 mg/L抗坏血酸、120 mg/L硫代硫酸钠可完全抑制PPO活力。现行甘蔗提汁的浸渗工艺较适合蔗汁酶促褐变反应,应作相应的调整。

Experiments were performed to extract and purify the polyphenoloxidase （PPO） in sugarcane. The characteristics Of PPO were also studied. The result showed that using catechol as the substrate, the kinetic equation of PPO was V = 1250[S]/ （54. 4 ＋ IS] ） and Km was 54. 4 mmol/L.The O-polyphenols in sugarcane was the optimum substrates. The optimum pH value and temperature were 6.2 and 40℃ respectively. Enzyme was relatively stable at pH5.8 and temperature below 30%. Six kinds of sugarcane PPO inhabitants were tested. The inhibited effects of citric acid, oxalic acid, ethylenediaminetetraacetic acid （EDTA） on PPO were not obvious. 70 mg/L sodium bisulfite, 110 mg/L ascorbic acid, 120 mg/L sodium thiosulfate could inhibit PPO activity completely. The imbibition technology of the current extraction process was suitable for juice enzymatic browning reaction, so it should be adjusted accordingly.