摘要
为解决生物酶在战场应用环境中易失活且环境耐受性差的问题,我们合成了大环多胺双锌模拟酶配合物-2,6-双{[双(2-羟乙基)氨基]甲基}-4-甲基酚(Zn L2).Zn L2对GD(Soman,梭曼)具有较高的催化活性,能够实现多次催化循环,并且在Zn L2与GD化学计量比为(0.56∶1)的条件下水解率为100%.使用高效液相色谱-质谱与核磁共振确定催化产物为甲氟膦酸酯、甲氟膦酸、甲基膦酸频哪酯与甲基膦酸,说明Zn L2水解GD为双平行反应,反应途径分别为GD的P—F与P—O键的断裂.建立在实验的基础上,使用密度泛函理论(DFT)的B3LYP方法,从P—O与P—F键断裂这两个平行反应方向对催化过程进行计算.计算结果表明:Zn L2上Ot末端醇盐作为一个碱试剂去激活水分子,使其成为羟基并作为亲核试剂进攻中心磷原子,形成一个五配位的磷酰中间体,通过进一步亲核进攻水解中间体形成最终P—O与P—F键断裂产物.Zn L2催化GD水解的活化能为分别为5.6 kcal/mol(P—F键断裂)和11.5 kcal/mol(P—O键断裂),说明P—O键断裂过程是GD酶促水解反应的速控步骤.
For solving the problems of inactivation and weak endurance of natural enzymes in battlefield environment,this paper reported that a binuclear zinc artificial enzyme（ Zn L2）,i. e. a complex of two Zn（ II） ions with a macrocyclic ployamino ligand（ 2,6-bis{ [bis（ 2-hydroxyethyl） amino]methyl}-4-methylphenol,Zn L2）,has a high catalytic activity for cyclic catalyzing of GD（ Soman）,with a 100% conversion obtained at a stoichiometry ratio of 0. 56∶ 1（ Zn L2∶ GD）. Using in-situ NMR and HPLC-MS,the products from the Zn L2-catalyzed hydrolysis of GD have been verified to include methyl phosphonic acid,pinayl methylphosphate,fluorophosphonic acid and fluorophosphate. This indicates that there are two parallel reactions in the hydrolysis of GD,respectively involving the cleavages of the P—F and P—O bonds in the GD substrate. The experimental results were validated by the subsequent B3 LYP method of DFT,which proposed a similar step-wise mechanism for the parallel reactions,i. e. a nucleophilic attack on the substrate phosphor by a water activated by a ligand alkoxide leading to a penta-coordinated phosphoryl intermediate,followed by the hydrolysis of phosphoryl intermediate（ the dissociation of the P—F or P—O bond）. The activation energy of the hydrolysis of GD by Zn L2 catalysis were 5. 6 kcal / mol（ P—F breakdown） and 11. 5 kcal / mol（ P—O breakdown）,respectively. Thus the P—O breakdown is the rate-determining step of GD enzymatic hydrolization.
出处
《分子催化》
EI
CAS
CSCD
北大核心
2015年第6期575-585,共11页
Journal of Molecular Catalysis(China)
基金
国家自然科学基金(21373027)~~
关键词
大环多胺金属模拟酶
催化水解
梭曼
密度泛函理论
亲核进攻
macrocyclic ployamino metal artificial enzyme
catalytic hydrolysis
GD
density functional theory（DFT） calculation
nucleophilic attack
