高强脉冲电场处理对木瓜蛋白酶的影响

Inactivation of Papain by the Treatment of Pulsed Electric Fields

用高强脉冲电场处理木瓜蛋白酶,研究了电场强度、脉冲数目、温度、剪切效应等因素对酶活性的影响。结果表明:高强脉冲电场可致木瓜蛋白酶失活,且失活率与电场强度和脉冲数目呈正比。还原剂、温度和不同流速产生的剪切效应对酶活的影响很小。由此推论酶的失活并非活性部位半胱氨酸的氧化、电化学反应等外部因素引起而是酶的结构或活性部位的构象等内部因素在脉冲电场作用下变化的结果。

The effects of pulsed electric fields （PEF） on the activity of papain were studied. Some affective factors such as the electric field strength, number of pulses, treatment temperature and shearing effects were changed. Results showthat： the treatment of PEF （up to 50 kV/cm） can cause the inactivity of papain, and the inactivity rate increases with the increasing of the electric field strength and number of pulses. The maximum inactive rate （88. 5%） can be observed at 50 kV/em when the number of puises is 20 000. Reducing agents, temperature and shearing strength have little effect on the activity of papain. So some mechanisms can be deduced that structural change while the oxidation of papain active site may not be the major reason of papain inactivation by PEF but a cyteine residue.