【摘要】 本文研究了仙人掌中多酚氧化酶(PPO)的特性以及一些抑制剂对其活性的影响。结果表明:仙人掌中PPO的最适温度为50℃,最适pH有两个,分别为pH4.0和pH7.0,因而在仙人掌中的PPO存在同工酶。柠檬酸、抗坏血酸及EDTA对仙人掌PPO均有一定的抑制效果,抑制能力顺序为:柠檬酸>抗坏血酸>EDTA。对各种抑制剂的作用机理进行了探讨。EDTA主要是通过螯合PPO中的辅酶因子Cu2+而起作用,抗坏血酸螯合Cu2+的能力比EDTA弱,但抗坏血酸的还原能力较强,而柠檬酸则是通过降低pH和螯合作用抑制PPO。更多还原

【Abstract】 This paper studied the characteristics and inhibition of polyphenoloxidase(PPO) in Opuntia dillenii. The resultsshowed: the optimum temperature of PPO was 50℃ and the optimum pHs were 4.0 and 7.0 respectively, so as to display thatthere were two isoenzymes. All citric acid, ascorbic acid and ethylene diamine tetraacetic acid(EDTA) had certain inhibitoryeffects., Their inhibiting capability to the PPO was in the order as follows: citric acid>ascorbic acid>EDTA. It had inhibitoryeffect on the PPO that EDTA mainly chelated the Cu2+ as co-enzyme factory of PPO. The chelating ability of ascorbic acid toCu2+ was weaker than EDTA, but the reducing ability of ascorbic acid was stronger than EDTA, while citric acid inhibited thePPO through both reducing pH and chelating Cu2+.更多还原