芦荟多酚氧化酶特性的研究

研究了芦荟多酚氧化酶的基本性质。以邻苯二酚为底物,采用分光光度法在4 10nm处测定芦荟多酚氧化酶的活性,研究了温度、pH值、底物浓度以及酶浓度对其活性的影响,并建立了酶促褐变反应动力学方程。实验结果表明,芦荟多酚氧化酶的最适温度为4 0℃,最适pH值为6 5 ,其酶促褐变反应动力学符合米氏方程所描述的单底物酶促反应动力学,相应的动力学参数Km=0 2 8mol/L ,Vmax=2 32×10 -2 U/min。文中还研究了利用蛋白酶抑制褐变的方法,以芦荟多酚氧化酶液(mL)∶木瓜蛋白酶(mL ,浓度0 5mg/mL) =5∶1的比例向芦荟多酚氧化酶粗酶液中添加木瓜蛋白酶,在5 5℃、pH5 7条件下,水解10min可较好地抑制多酚氧化酶的活性,从而抑制芦荟的酶促褐变。

Study on Characteristics of Polyphenol Oxidase from Aloe

The properties of polyphenol oxidase extracted from aloe were investigated in this paper. The aloe polyphenol oxidase activities were spectrophotometrically determined at 410nm with catechol as substrate in different pH, temperature, substrate concentration and enzyme concentration. The reaction kinetic equation was also established in this study. Our results showed that the optimum temperature and pH of aloe polyphonel oxidase's was 40℃ and pH6.5, respectively. The reaction kinetic of enzymatic browning is accordant with Michaelis equation, the K m and V max were 0.28?mol/L and 2.32×10 -2 U/min, respectively.This paper also studied the inhibition effect of aloe polyphenol oxidase with proteases. Adding papain to aloe polyphenol oxidase with the proportion of polyphenol oxidase (mL):papain(mL,1mg papain in 1?mL phosphate buffer)=5∶1, thus resulted in the inhabitation of the aloe enzymatic browning.