莲雾果实多酚氧化酶的特性及抑制剂研究

研究了莲雾(Syzygium samarangense Merr.& Perry)果实多酚氧化酶的最适底物及活性的影响因素,并建立了酶促褐变反应动力学方程,探讨了亚硫酸氢钠、EDTA二钠、抗坏血酸、柠檬酸、硫酸钠等5种抑制剂对莲雾酶促褐变的抑制效果.结果表明,莲雾果实多酚氧化酶的最适底物为邻苯二酚,最适温度为40℃,最适pH为7.5;莲雾多酚氧化酶的单底物酶促反应动力学符合米氏方程,相应的动力学参数为Km=0.035 5 mol/L,Vmax=0.7789 U/min;5种不同抑制剂对该酶表现出不同的抑制作用,抑制效果由强到弱为亚硫酸氢钠、抗坏血酸、EDTA二钠、硫酸钠、柠檬酸.

Study on the Characteristic of Polyphenol Oxidase in Syzygium samarangense Fruit and Its Inhibitor

The optimum substrate and influencing factors of the activity of Syzygium samarangense polyphenol oxidase(PPO) were studied;and the reaction kinetic equation was also established.The inhibitory effect of sodium bisulfite,EDTA-2Na,ascorbic acid,citrate acid and sodium sulfate on enzymatic browning of S.samarangense was investigated.The result showed that the optimum substrate of PPO from S.samarangense was catechol;and the optimum temperature and pH for PPO was 40 ℃ and pH 7.5.The reaction kinetic of enzymatic browning was consistent with Michaelis equation;and corresponding kinetic parameters were Km = 0.035 5 mol/L and Vmax= 0.778 9 U/min.Five different inhibitor of the enzyme showed different inhibitory effects on S.samarangense PPO.The inhibitory effect decreased in the following order,sodium bisulfite,ascorbic acid,EDTA-2Na,sodium sulfate and citrate acid.