重金属汞对土壤酸性磷酸酶的影响及其机理

Studies on the effects and corresponding mechanism of Hg^(2+) on the activity of soil acid phosphatase

通过土壤培养试验、紫外吸收光谱和荧光光谱技术 ,研究了重金属汞对土壤酸性磷酸酶催化活性、动力学性质的影响及机理 .结果表明 ,汞对土壤酸性磷酸酶活性、酶促反应动力学性质均具有显著影响 .汞对土壤酸性磷酸酶的作用可能为非竞争与反竞争混合的抑制类型 .而汞对麦芽酸性磷酸酶的抑制作用为反竞争性抑制 .重金属汞通过改变土壤酸性磷酸酶分子色氨酸、酪氨酸残基的微环境致使酶活性中心的构象发生变化 。

By fluorescence and differential UV-absorption spectra, the effects of Hg^(2+) on the activity and kinetic property of soil acid phosphatase were studied in soil culture under laboratory conditions, the corresponding mechanism was discussed as well. The obtained results revealed that Hg^(2+) had significant influences on the above characteristics of soil acid phosphatase. Data for kinetic studies suggested that the interaction between Hg^(2+) and soil acid phosphatase probably be mixed types of non-and anti-competitive inhibition interactions, whereas Hg^(2+) was an anti-competitive inhibitor of acid phosphatase from wheat germ. In addition, Hg^(2+) changed the microenvironment of tryptophan and tyrosine groups of soil acid phosphatase, which were active sites of the enzyme and consequently inhibited the activity of the enzyme.