Human paraoxonases (PON1, PON2, and PON3) are lactonases with overlapping and distinct substrate specificities
Human paraoxonases (PON1, PON2, and PON3) are lactonases with overlapping and distinct substrate specificities
复制标题
DOI：
10.1194/jlr.m400511-jlr200
复制
发表时间：
2005-06-01
影响因子：
6.5
通讯作者：
La Du, BN
中科院分区：
文献类型：
--
作者：
Draganov, DI;Teiber, JF;La Du, BN
人类对氧磷酶(PON)基因家族有三个成员：PON1、PON2和PON3。它们的生理作用(S)和天然底物尚不确定。我们开发了一种杆状病毒介导的表达系统，适用于所有三个人的脑桥，并优化了它们的纯化程序。重组的桥本是用高甘露糖型糖进行糖基化的，高甘露糖型糖对蛋白质的稳定性很重要，但对它们的酶活性不是必需的。对纯化的Pons的酶学鉴定表明，它们是内酯酶/内酯酶，有一些重叠的底物(如芳香族内酯)，但也具有独特的底物特异性。这三种桥本均能高效代谢花生四烯酸和二十二碳六烯酸的内源底物5-羟基二十碳四烯酸1，5-内酯和4-羟基二十二碳六烯酸，它们分别是花生四烯酸和二十二碳六烯酸的酶和非酶氧化产物，可能是桥本的内源底物。有机磷几乎完全被PON1水解，而大型药物底物，如洛伐他汀和螺内酯只被PON3水解。特别令人感兴趣的是人类脑桥，特别是PON2，水解N-酰基高丝氨酸内酯的能力，从而使其失活，这是病原菌的群体感应信号。在体外，重组桥蛋白对铜诱导的低密度脂蛋白氧化均无保护作用。
The paraoxonase (PON) gene family in humans has three members, PON1, PON2, and PON3. Their physiological role(s) and natural substrates are uncertain. We developed a baculovirus-mediated expression system, suitable for all three human PONs, and optimized procedures for their purification. The recombinant PONs are glycosylated with high-mannose-type sugars, which are important for protein stability but are not essential for their enzymatic activities. Enzymatic characterization of the purified PONs has revealed them to be lactonases/lactonizing enzymes, with some overlapping substrates (e. g., aromatic lactones), but also to have distinctive substrate specificities. All three PONs metabolized very efficiently 5-hydroxy-eicosatetraenoic acid 1,5-lactone and 4-hydroxy-docosahexaenoic acid, which are products of both enzymatic and nonenzymatic oxidation of arachidonic acid and docosahexaenoic acid, respectively, and may represent the PONs' endogenous substrates. Organophosphates are hydrolyzed almost exclusively by PON1, whereas bulky drug substrates such as lovastatin and spironolactone are hydrolyzed only by PON3. Of special interest is the ability of the human PONs, especially PON2, to hydrolyze and thereby inactivate N-acyl-homoserine lactones, which are quorum-sensing signals of pathogenic bacteria. None of the recombinant PONs protected low density lipoprotein against copper-induced oxidation in vitro.