K^+对促进甲基对硫磷水解酶催化活性的影响  

Regulation of catalytic efficiency of methyl parathion hydrolase by K^+

作　　者：石诚 刘松 堵国成[2] SHI Cheng;LIU Song;DU Guocheng(Key Laboratory of Industrial Biotechnology,Ministry of Education,Jiangnan University,Wuxi 214122,China;School of Biotechnology,Jiangnan University,Wuxi 214122,China)

机构地区：[1]江南大学,粮食发酵工艺与技术国家工程实验室,江苏无锡214122 [2]江南大学生物工程学院,江苏无锡214122

出　　处：《食品与发酵工业》2020年第6期8-12,共5页Food and Fermentation Industries

基　　金：国家自然基金面上项目(31771913)。

摘　　要：甲基对硫磷水解酶(methyl parathion hydrolase,MPH)能催化甲基对硫磷等有机磷化合物中P-O、P-F、P-CN及P-S键的水解。该研究考查了K^+对MPH催化活性的影响,并分析了K+调控酶蛋白活性的作用位点。酶活分析显示,Pseudomonas sp.WBC-3 MPH催化活性随K+浓度增加而迅速提高,MPH在3 mol/L K^+溶液中的催化活性较无K+条件下提高13.39倍。基于MPH进行分子动力学分析,建立了MPH氨基酸残基临近区域K+分布概率的预测方法。预测结果表明,1 mol/L K^+溶液中K+倾向分布于MPH的Asp、Glu、Gln及Asn残基附近,并降低了A85-T95与V323-N329区域的柔性。将A85-T95与V323-N329柔性变化最大的E94与N329分别突变为Ala,使MPH相对活性(1 mol/L K^+溶液/0 mol/LK^+溶液)分别较野生酶降低26%与33%;两者同时突变为Ala,其催化活性降低53%。上述结果表明,K^+通过与E94、N329相互作用来调控MPH催化,为其催化活性的分子改造提供了靶点。Methyl parathion hydrolase(MPH)can catalyze the hydrolysis of P-O,P-F,P-CN and P-S bonds in organophosphorus compounds such as methyl parathion.In this study,the effect of K+on the catalytic activity of MPH was investigated,and the residues interacting with K+on the activity of MPH were also analyzed.Enzymatic activity analysis showed that the activity of MPH increased rapidly with the increase in ion concentration of potassium.The catalytic activity of MPH in 3 mol/L K^+solution was 13.39 times higher than that in the absence of K^+.Based on the molecular dynamic analysis of MPH,the prediction method of K+distribution in the vicinity of amino acid residues of MPH was established.The predicted results showed that K^+tends to distribute near Asp,Glu,Gln and Asn residues of MPH,and reduced the flexibility of A85-T95 and V323-N329 regions.The most flexible residues E94 and N329 in these two regions were mutated into Ala,which reduced the relative activity of MPH(1 mol/L K^+/0 mol/L K^+)by 26%and 33%respectively and mutating both the residues into Ala reduced the relative activity by 53%.These results indicated that K^+regulated MPH reaction by interacting with E94 and N329,which provides target residues for molecular modification to enhance MPH activity.

关 键 词：甲基对硫磷水解酶 K^+ 分子动力学 离子分布概率 调控位点 

分 类 号：Q55[生物学—生物化学]