杨桃多酚氧化酶粗酶液经过DEAE-Toyopearl650M离子交换柱层析,Butyl-Toyopearl650M疏水柱层析后,被纯化了21.6倍,回收率为45.2%。该酶能迅速地催化焦性没食子酸的酶促氧化反应,而对邻苯二酚、间苯二酚、对苯二酚和绿原酸则完全无催化活性。该酶对焦性没食子酸的Km值为7.92mmol/L,其最适pH为8.0,pH稳定性范围在pH4.0-11.0,最适温度为60℃,热稳定性相对较高,在≥90℃加热30min后仍残留约9%的酶活性。该酶的最佳抑制剂是抗坏血酸,其次是NaHSO3和盐酸-L-半胱氨酸,Cu2+、Zn2+、Ca2+等金属离子对该酶也有一定的抑制作用。

Polyphenol oxidase in carambola was partially purified to 21.6-fold with a recovery of 45.2% through chromatographies on DEAE-Toyopearl 650M and Butyl-Toyopearl 650M columns.The purified enzyme quickly oxidized pyrogallic acid,and had no activity towards catechol,resorcinol,hydroquinone and chlorogenic acid.The Km value of the enzyme for pyrogallic acid was 7.92mmol/L.The optimum pH was 8.0,and the enzyme activity was stable with pH in the range of 4.0-11.0.The enzyme had an optimum temperature of 60℃ and was relatively stable at higher temperature:9% of the PPO activity remained after a heat treatment at 90℃ for 30 min.The strongest inhibitors of the enzyme activity were ascorbic acid,followed by NaHSO3 and hydrochloride-L-cysteine.The enzyme was also inhibited by metal ion such as Cu2+,Zn2+ and Ca2+.