用乙酰胆碱酯酶和硫代黄素T体系的荧光猝灭测定有机磷农药

Determination of Organophosphorus Pesticide Residues by using Fluorescence Quench in the System of Acetylcholinesterase-Thioflavin T

在pH7．0的磷酸盐缓冲溶液中，硫代黄素T与乙酰胆碱酯酶相互作用，酶的内源荧光被硫代黄素T猝灭，而在490nm处产生硫代黄素T的特征荧光发射峰。在该体系中加入有机磷农药对氧磷后，硫代黄素T的特征荧光峰被猝灭，荧光猝灭强度AF与对氧磷浓度CP2存在线性关系，其线性浓度范围为0．20～2．40mg／L，回归方程为△F=0．041CP2（μg／L）＋84．17，相关系数为0．9984，检出限（3σ）为7．87μg／L。对检测原理的探讨表明，硫代黄素T使乙酰胆碱酯酶内源荧光静态猝灭，二者形成了超分子复合物，产生了特征荧光峰；但是，有机磷农药对氧磷可破坏此复合物，因而硫代黄素T的特征荧光峰被猝灭。相比利用酶的抑制原理来检测农药残留的方法，该方法具有简便、快速、不需要消耗酶的底物的优点。

In pH 7.0 phosphate buffer solution, the acetylcholinesterase（ACHE） intrinsic fluorescence was quenched by thioflavin T, and a new florescence peak of thioflavin T presented at 490nm. When paraoxon was added, the peak decreased sharply. The results showed that the intensity of fluorescence quenching at 490nm （AF） was linear to the paraoxon concentration C P2 in the range of 0.20 - 2.40mg/L. The regression equation was △F = 0.041 CP2 （μg/L） ＋ 84.17, and the correlation coefficient was 0. 9984. The detection limit （3 σ ） was 7.87μg/L for paraoxon. The study demonstrated that static quenching existed in the AChE-thioflavin T supramolecular complex. Addition of paraoxon to the AChE-thioflavin T complex leads to in a decrease in fluorescence intensity at 490nm due to displacement of the thioflavin T from the acetylcholinesterase. The results showed that the method was accurate, rapid, simple and zero consumption of substrate of enzyme comparing with conventional method by theory of inhibition.