香蕉果肉过氧化物酶初步纯化及特性研究

目的]为控制香蕉POD引起的酶促褐变提供理论依据。方法]采用饱和度70%硫酸铵盐析和DEAE-Toyopearl 650M离子交换柱层析分离纯化果肉POD,测定香蕉酶液中POD活性和蛋白质含量。结果]香蕉提取酶液中POD被纯化了约7.3倍,回收率为33.8%。香蕉果肉POD对愈创木酚的Km值为5.98 mmol/L,其最适pH值为6.5,pH值稳定性为pH 6.0~10.0,最适反应温度为35℃。盐酸-L-半胱氨酸、抗坏血酸能显著地抑制香蕉果肉POD的活性,亚硫酸氢钠、植酸、柠檬酸也能有效地抑制该酶活性;而Cu2+对香蕉果肉POD则有明显的激活作用。结论]香蕉果肉POD的热稳定性低于香蕉PPO热稳定性,其有效的化学抑制剂与香蕉PPO基本一致。

Partial Purification and Characteristic Study of Peroxidase from Banana(Musa spp.)

Objective]The research aimed to provide theory references for the control of browning in banana(Musa spp.)caused by peroxidase(POD).Method]Peroxidase in banana was partially purified with 70% ammonium sulfate fractionation and chromatography on DEAE-Toyopearl 650M column,and its activity was identified together with protein content. Result]Peroxidase was purified to 7.3-fold with a recovery of 33.8% from banana extracts.The Km value of the enzyme for substrate guaiacol was 5.98 mmol/L.The optimum pH value was at 6.5,and the enzyme activity was stable in the range of pH 6.0-10.0.The enzyme had an optimum temperature of 35℃.The strongest inhibitors of the enzyme activity were L-ascorbic acid and hydrochloric acid-L-cysteine,followed by NaHSO3,phytic acid,citric acid.The enzyme was strongly activated by Cu2+.Conclusion]The heat stability of banana POD was lower than that of banana PPO,and the effective inhibitors of banana POD were similar to those of banana PPO.