血清及高密度蛋白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J（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270nm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、pH、激活剂Ca^2 、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5mmol/L，最适pH为8．0，必需激活剂Ca^2 浓度为2mmol/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]

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 Ca2+, and inhibitor EDTA, we found the best conditions of reaction to be: substrate concentration 5 mmol/L, pH8.0, and Ca2+ 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.