电子束辐照对多酚氧化酶活性及结构的影响

Effects of electron beam irradiation on the activity and structure of tyrosine oxidase

应用圆二色谱及SDS-PAGE技术分析电子束辐照对多酚氧化酶(Polyphenol oxidase,PPO)活性及结构的影响。结果发现:电子束辐照可在一定程度上降低PPO酶活性;圆二色谱分析发现电子束辐照处理后,PPO酶蛋白质二级结构相对含量发生改变,但a螺旋、b折叠和b转角总含量在吸收剂量<4.83 kGy时总量变化不大,当吸收剂量>4.83 kGy时,随着剂量的增加含量不断下降,无规则卷曲呈上升趋势。SDS-PAGE电泳实验结果表明,辐照处理下PPO酶同时发生交联和降解反应。上述结果提示电子束辐照对PPO酶活性有一定的抑制作用。

The influence of electron beam irradiation on the activity and structure of PPO （Polyphenol oxidase） was analyzed. The results showed that electron beam irradiation can reduce PPO enzyme activity to a certain extent at a dose lower than 4.83 kGy. Analysis by circular dichroism （CD） showed that PPO protein＇s relative content of secondary structure affected by electron beam irradiation and total content of alpha helix, beta, and beta folding angle changed slightly. In contrast, at a dose higher than 4.83 kGy, the total content of the alpha helix, beta folding, and beta angle declined, and the random curl content increased. SDS-PAGE results showed that simultaneous cross-linking and degradation of the PPO enzyme occurred during irradiation. The experimental results indicate that electron beam irradiation can inhibit the activity of PPO.