血清及高密度脂蛋白中对氧磷酶活性的分光光度测定法

目的　在现有的实验条件下 ,获得稳定可靠的血清及高密度脂蛋白 (high density lipoprotein,HDL)中对氧磷酶 (paraoxonase,PON)活性的测定方法。方法　以乙酸苯酯为底物 ,在对氧磷酶的作用下水解 ,生成产物苯酚 ,测定 5分钟内反应体系中在 2 70 nm处苯酚特征性的紫外吸收 ,换算为酶促反应速度。结果　通过观测底物浓度、p H、激活剂 Ca2 + 、抑制剂 EDTA等对酶促反应的影响 ,得出最适的测定条件 :底物浓度为 5 m mol/ L ,最适 p H为 8.0 ,必需激活剂 Ca2 +浓度为 2 mmol/ L。结论　在该反应条件下 ,测定不同浓度 HDL 或血清中该酶的活性 ,重复性和稳定性均符合要求

Determination of Paraoxonase Activities in Serum and HDL Fu Qiang, Liu Bingwen. Apolipoproteins Research Unit, Institute of Biochemistry and Molecular Biology, WCUMS, Chengdu 610041, China

Objectvie To establish a reliable method of determining the activity of paraoxonase(PON) in serum and high density lipoprotein(HDL). Methods We used phenylacetate(PA) as substrate and investigated the hydrolysis of PA catalyzed by serum PON or HDL PON.The PON activities were calculated from the velocities of reaction that had been determined by the increasing absorbance of product p phenol within the first 5 minutes.Results Through the studies on the effects of substrate concentration, pH, activator Ca 2+ , and inhibitor EDTA, we found the best conditions of reaction to be: substrate concentration 5 mmol/L, pH8.0, and Ca 2+ concentration 2 mmol/L. And we established the method with good reproducibility and stability. Conclusion Under the above stated conditions, it is reliable to determine the activity of paraoxonase in serum and HDL.