Oxidative Stress Research Laboratory, MIGAL-Galilee Technology Center, Kiryat Shmona 11016, Israel.
Free Radic Biol Med. 2011 Jan 1;50(1):148-56. doi: 10.1016/j.freeradbiomed.2010.10.708. Epub 2010 Oct 29.
Paraoxonase 1 (PON1) is an HDL-associated lactonase with antiatherogenic properties. These include dampening the oxidation properties of human carotid lesion lipid extract (LLE), which in turn inactivates the enzyme. The aims of this study were to identify the PON1 inhibitor in LLE and explore the mechanism of inhibition. LLE inhibited both recombinant PON1 and HDL-PON1 lactonase activity in a dose- and time-dependent manner. Addition of antioxidants or electrophiles to LLE did not prevent PON1 inhibition. LLE was unable to inhibit a PON1 mutant lacking Cys284, whereas it did inhibit all other PON1 mutants tested. The inhibitor in the LLE was identified as linoleic acid hydroperoxide (LA-OOH) and inhibition was specific to this hydroperoxide. During its inhibition, PON1 acted like a peroxidase enzyme, reducing LA-OOH to LA-hydroxide via its Cys284. A similar reaction occurred with external thiols, such as DDT or cysteine, which also prevented PON1 inhibition and restored enzyme activity after inhibition. Thus, the antiatherogenic properties of HDL could be, at least in part, related to the sulfhydryl-reducing characteristics of its associated PON1, which are further protected and recycled by the sulfhydryl amino acid cysteine.
对氧磷酶 1（PON1）是一种具有抗动脉粥样硬化特性的高密度脂蛋白相关内酯酶。这些特性包括抑制人颈动脉病变脂质提取物（LLE）的氧化特性，进而使酶失活。本研究的目的是鉴定 LLE 中的 PON1 抑制剂并探讨其抑制机制。LLE 以剂量和时间依赖的方式抑制重组 PON1 和 HDL-PON1 内酯酶活性。向 LLE 中添加抗氧化剂或亲电试剂并不能预防 PON1 抑制。LLE 不能抑制缺乏半胱氨酸 284 的 PON1 突变体，但它可以抑制所有其他测试的 PON1 突变体。LLE 中的抑制剂被鉴定为亚油酸氢过氧化物（LA-OOH），并且抑制作用是特异性的。在抑制过程中，PON1 充当过氧化物酶，通过其半胱氨酸 284 将 LA-OOH 还原为 LA-氢氧化物。类似的反应发生在外部硫醇（如 DDT 或半胱氨酸）上，这也可以防止 PON1 抑制，并在抑制后恢复酶活性。因此，HDL 的抗动脉粥样硬化特性至少部分与与其相关的 PON1 的巯基还原特性有关，巯基氨基酸半胱氨酸进一步保护和循环利用了该特性。
