波尔多液对土壤过氧化氢酶活性与构象的影响

Effects of Bordeaux Mixture on Soil Catalase Activity and Conformation Characteristics

为初步探讨波尔多液对土壤过氧化氢酶的作用机理及变化规律,采用人工模拟和荧光光谱法研究了波尔多液对土壤过氧化氢酶活性特征及构象的影响.结果表明:1)不同浓度波尔多液对土壤过氧化氢酶活性总体呈现低浓度激活、高浓度抑制作用.不同配制方式波尔多液对土壤过氧化氢酶活性抑制效应顺序为多倍量式>倍量式>半量式>等量式.浓度为200mg·kg-1左右的等量式波尔多液处理对土壤过氧化氢酶活性的影响最小.2)24h培养时间下,随波尔多液浓度的增加,酶促反应米氏常数Km和最大反应速率Vmax均呈先减小后增大趋势.统计分析表明,Km和Vmax均与波尔多液浓度呈显著正相关(p<0.01),土壤过氧化氢酶Km值可表征波尔多液对土壤过氧化氢酶活性的影响程度,其作用机理为反竞争性抑制类型.3)波尔多液对离体过氧化氢酶的内源荧光有较强的猝灭作用,Cu(Ⅱ)和离体过氧化氢酶的结合常数K及结合位点数n分别为69.1831mol·L-1和0.6878.

In order to explore the mechanism and rule of action of Bordeaux mixture to soil catalase activity, effects of Bordeaux mixture on characteristic parameters and conformation of soil catalase were investigated using simulating method and fluorescence spectrum method. Results showed that 1）Soil catalase activity was stimulated by the low Bordeaux mixture concentrations and inhibited by the high Bordeaux mixture concentrations. The order of inhibition effect on the soil catalase with different Bordeaux mixture proportioning was multi-times〉double-times〉half-times〉equal-times. The treatment which had the smallest effect on the soil catalase was the Bordeaux mixture treatment of 200mg·kg-1 and equal-times. 2）Under the culture time of 24h, Km and Vmax of enzymatic reaction were decreased at first and then increased with the increase of Bordeaux mixture concentrations. Statistical analysis indicated that Km and Vmax had significantly positive correlations with Bordeaux mixture concentrations, which implied that the Km values could reflect the degree of Bordeaux mixture affecting on soil catalase and Bordeaux mixture behaves as a typical uncompetitive inhibitor to soil urease in this experiment. 3）The influence of Bordeaux mixture on in vitro catalase was studied by molecular fluorescence spectrum. The Bordeaux mixture had a strong ability to quench the endogence fluorescence of in vitro catalase. According to the fluorescence quenching results between Cu （Ⅱ）and in vitro catalase, the binding constant K was 69.1831mol·L-1 and the number of binding site n was 0.6878.