三(2-苯并咪唑甲基)胺-锌(Ⅱ)配合物模拟水解酶催化酯类水解研究

Hydrolytic Metalloenzyme Activity of Zinc(Ⅱ) Complex of Tris (2-benzimidazylmethyl) amine

研究了三（2-苯并咪唑甲基）胺-锌（II）配合物作为水解酶模拟物催化乙酸对硝基苯酯（NA）水解动力学．结果表明，催化水解速率对NA及配合物浓度呈一级反应．水解速率遵循速率方程v=（kcat[Zn]＋kOH[OH－]＋k0）[NA]．在298K，I=0．10mol／LKNO3，0．02mol／LTris，40％CH3CN水溶液中，二级反应速率常数kcat和kOH分别为0．12、1．45mol－1·L·S－1，k0为NA溶剂解的速率常数，其值为3．70×10－6s－1．与10％CH3CN溶液中的k0值相比，40％CH3CN水溶液中的k0值明显降低．本研究表明三（2-苯并咪唑甲基）胺-锌（II）配合物能有效地催化NA的水解．配合物对NA水解的催化作用受酸碱平衡控制．根据实验结果提出了催化反应的机理．

The hydrolytic kinetics of p-nitrophenol acetate(NA) catalyzed by zinc(II) com-plex of Tris (2-benzimidazylmethyl)amine (NTB) has been studied. It was shown that the catalytic hydrolytic rate is of first-order to both zinc(II) complex and NA concentrations.The second-order rate constant is kcat=0.12mol-1·L·s-1 (T=298K, I=0.10mol/L KNO3,0.02mol/L Tris buffer, 40% CH3CN aqueous solution).This is one of the most efficient hydrolytic metalloenzyme model compounds reported up to now. The increase of CH3CN contents in the solution greatly decreased the hydrolytic activity of the nucleophiles.