宣木瓜多酚氧化酶酶学特性与抑制剂研究

研究宣木瓜不同部位的多酚氧化酶(PPO)的活性及其温度、pH值、底物专一性等特性和抑制方法。结果表明：果心中的PPO活性明显高于果皮和果肉，宣木瓜组织的褐变主要是由多酚氧化酶引起；PPO最适底物为邻苯二酚；最适温度20℃，在80℃处理5min即可钝化PPO的活性；最适pH5.5，在酸性条件下稳定性优于碱性；抗坏血酸、L-半胱氨酸、亚硫酸氢钠、柠檬酸和氯化钠均能有效的抑制PPO的活性。

Enzymatic Characteristics and Inhibitors of Polyphenol Oxidase from Chaenomeles speciosa Nakai Fruits

Effects of temperature, pH, substrate, ascorbic acid, L-cysteine, sodium bisulfite, citric acid and sodium chloride on the activity of polyphenol oxidase (PPO) from Chaenomeles speciosa Nakai were studied. Results showed that PPO activity was obviously higher in core than in the peel and flesh. The browning of C. speciosa fruit was significantly correlated to PPO activity. The PPO from C. speciosa fruit had the optimum substrate of catechol, with the optimum temperature 20 ℃ and pH 5.5. The enzyme lost its activity substantially after exposure to 80 ℃ for 5 min. Its activity was suppressed effectively by ascorbic acid, L-cysteine, sodium bisulfite, citric acid and sodium chloride.