含新型亲核体大环多胺锌(II)配合物对水解酶的模拟研究

本文探讨苯酚功能化的大环多胺配体6-(2'-羟基-3', 5'-二溴)-苄基-1, 4, 8, 11-四氮杂环十四烷(L)锌(II)配合物作为水解酶模拟物催化4-硝基苯酚醋酸酯(NA)水解的动力学。研究表明催化水解速率对NA及配合物浓度皆呈一级反应。水解速率遵循速率方程V=(kcatZn]+kOHOH^-]+k0)NA]。其二级反应速率常数kcat在一定范围内随着pH值的增加而增加, kcat的最大值(k)和kOH分别为0.12, 8.55mol^-^1.L.s^-^1。k0为NA的溶剂解速率常数, 其值为1.122×10^-^5s^-^1(298K, I=0.10,0.02mol.L^-^1tris缓冲溶液)。kcat值较以前报道的配合物更大, 催化活性更高。显示配位酚羟基可作为一种新型亲核体有效地催化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。

Hydrolytic metalloenzyme activity of zinc(II) complex of macrocyclic polyamines

The hydrolytic kinetics of p-nitrophenol acetate (NA) catalysized by zinc(II) complex of 6-(2'-hydroxyl-3', 5'-dibromo)-benzyl-1, 4, 8, 11-tetraazacyclotetradecane has been studied. It was shown that the catalytic hydrolytic rate was of first-order to both zinc(II) complex and NA concentrations. The second-order rate constant kcat=0.12 mol^-^1. L. s^-^1 (298K, I=0.10, 0.02 mol.L^-^1 tris buffer). This is one of the most efficient hydrolytic metalloenzyme model compounds reported up to now. The present results show that coordinated phenolate can serve as a new nucleophile that effectively catalyzes the hydrolysis of NA.