The effect of homocysteine thiolactone on paraoxonase and aryl esterase activity of human serum purified paraoxonase 1 in vitro experiments.

IF 0.5 Q4 CARDIAC & CARDIOVASCULAR SYSTEMS
Elham Moshtaghie, Hashem Nayeri, Ali Asghar Moshtaghie, Sedigheh Asgary
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引用次数: 0

Abstract

Background: The important role of lipoproteins, particularly low-density lipoprotein (LDL) and high-density lipoprotein (HDL), has been highly regarded among the known causes of cardiovascular disease (CVD). A wide range of risk factors may cause structural and functional changes in lipoprotein particles, resulting in deposition and formation of atherosclerotic plaques. Homocysteine is one of the most important risk factors in heart disease, and its atherosclerotic properties appear to be related to its intermediate metabolite called homocysteine thiolactone (HCTL). The major aim of the present investigation was to study the effect of HCTL in different concentrations (10, 50, and 100 μM) on paraoxonase and aryl esterase activities of purified human serum paraoxonase 1 (PON1) antioxidant enzyme related to HDL, as an extracellular hydrolyzing enzyme of HCTL.

Methods: In order to purify PON1 enzyme from human serum, three-step chromatographic methods including DEAE Sephadex A50, Sephadex G100, and DEAE Sephadex A50 were used. Protein concentration and paraoxonase and aryl esterase activities of each fraction were measured separately and the highest activities fractions were collected and subsequently pooled together for the next steps. Ultimately, both activities of PON1 in the presence of different concentrations of HCTL were measured in triplicate by spectrophotometry technique.

Results: HCTL at concentrations of 50 and 100 μM decreased both paraoxonase and aryl esterase activities (P < 0.05) in comparison with the control group, which is directly related to the increase in HCTL concentration. However, at a concentration of 10 μM HCTL, no significant difference was observed in both paraoxonase and aryl esterase activities compared to the control group.

Conclusion: HCTL is a highly toxic and reactive compound that is produced in all cells. Extracellular enzyme PON1 causes its hydrolysis with high efficiency. The results obtained from the present study showed that paraoxonase and aryl esterase activities decreased in vitro in the presence of HCTL and therefore, HCTL may cause changing in the protein structure of this enzyme. Previous in vivo studies have also shown decrease of PON1 activity in patients with hyperhomocysteinemia.

Abstract Image

Abstract Image

Abstract Image

同型半胱氨酸硫内酯对人血清纯化对氧磷酶1的对氧磷酶和芳基酯酶活性的影响。
背景:脂蛋白,特别是低密度脂蛋白(LDL)和高密度脂蛋白(HDL)的重要作用,在已知的心血管疾病(CVD)的病因中受到高度重视。多种危险因素可能导致脂蛋白颗粒的结构和功能改变,从而导致动脉粥样硬化斑块的沉积和形成。同型半胱氨酸是心脏病最重要的危险因素之一,其动脉粥样硬化特性似乎与其中间代谢物同型半胱氨酸硫内酯(HCTL)有关。本研究主要目的是研究不同浓度(10 μM、50 μM和100 μM)的HCTL对纯化人血清中与HDL相关的对氧磷酶1 (PON1)抗氧化酶和芳基酯酶活性的影响,PON1是HCTL的胞外水解酶。方法:采用DEAE Sephadex A50、Sephadex G100、DEAE Sephadex A50三步色谱法从人血清中纯化PON1酶。分别测定各馏分的蛋白质浓度、对氧磷酶和芳基酯酶活性,并收集活性最高的馏分,汇总后进行下一步处理。最后,用分光光度法测定了PON1在不同浓度HCTL存在下的活性。结果:与对照组相比,HCTL浓度为50 μM和100 μM时对氧磷酶和芳基酯酶活性均降低(P < 0.05),这与HCTL浓度升高有直接关系。然而,在10 μM HCTL浓度下,对氧磷酶和芳基酯酶活性与对照组相比无显著差异。结论:HCTL是一种在所有细胞中产生的高毒性活性化合物。胞外酶PON1使其水解效率高。本研究结果表明,在体外,HCTL存在时,对氧磷酶和芳基酯酶活性降低,因此,HCTL可能引起该酶的蛋白质结构改变。先前的体内研究也显示高同型半胱氨酸血症患者的PON1活性降低。
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来源期刊
ARYA Atherosclerosis
ARYA Atherosclerosis CARDIAC & CARDIOVASCULAR SYSTEMS-
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