2羟-基-4-甲氧基苯甲醛和2羟-基-4-甲氧基苯甲酸对菜粉蝶多酚氧化酶的抑制作用

Inhibitory effects of 2-hydroxy-4-methoxy-benzaldehyde and 2-hydroxy-4-methoxy-benzoic acid on polyphenoloxidase of Pieris rapae(L.)

测定了2羟-基-4-甲氧基苯甲醛和2羟-基-4-甲氧基苯甲酸两种效应物对菜粉蝶多酚氧化酶(po lypheno lox idase,简称PPO,EC.1.14.18.1)催化L-多巴(L-DOPA)氧化活力的抑制作用。结果表明,这两种效应物对该酶的活性均有明显的抑制作用,抑制中浓度(IC50)分别为2.71和5.66 mm o l/L,抑制常数分别为2.82和3.35 mm o l/L;2羟-基-4-甲氧基苯甲醛对该酶的抑制作用显著高于2羟-基-4-甲氧基苯甲酸的;这两种抑制剂对酶的抑制作用机理完全不同,2羟-基-4-甲氧基苯甲醛对酶的作用表现为混合型抑制,而2羟-基-4-甲氧基苯甲酸对酶的作用表现为竞争性抑制。研究结果为设计以该酶为靶标的杀虫剂提供理论依据。

Inhibitory effects of 2-hydroxy-4-methoxy-benza[dehyde and 2-hydroxy-4-metnoxybenzoic acid on polyphenoloxidase （PPO） from larvae of Pieris rapae （L.） were studied. The results showed that both compounds could obviously inhibit enzyme activity for oxidation of L-DOPA, and their IC50 （inhibitor concentration leading to 50% activity lost） were 2.71 and 5.66 mmol/L, respectively. Their inhibition constants were 2.82 and 3. 35 mmol/L. Inhibitory ability of 2-hydroxy- 4-methoxy-benzaldehyde was much higher than that of 2-hydroxy-4-methoxy-benzoic acid. Inhibitory mechanisms of the two compounds were very different. The inhibition of 2-hydroxy-4-methoxy-benzaldehyde was mixed type while that of 2-hydroxy-4-methoxy-benzoic acid was competitive type.