Human Paraoxonase 1 Is the Enzyme Responsible for Pilocarpine Hydrolysis
Human Paraoxonase 1 Is the Enzyme Responsible for Pilocarpine Hydrolysis
复制标题
DOI：
10.1124/dmd.111.038141
复制
发表时间：
2011-08-01
影响因子：
3.9
通讯作者：
Yokoi, Tsuyoshi
中科院分区：
文献类型：
--
作者：
Hioki, Tomomi;Fukami, Tatsuki;Yokoi, Tsuyoshi
匹罗卡品已被广泛用于治疗青光眼的眼科制剂和治疗放射性口干症和干燥综合征的口服制剂。匹罗卡品在人体内的主要代谢途径是水解和羟化。研究发现，3-羟基化反应是由细胞色素P450 2A6负责的，但负责3-羟基化反应的酶还没有确定。在这项研究中，我们试图确定与匹罗卡品水解有关的酯酶。加入CaCl2后，人肝微粒体和血浆中的毛果芸香碱水解酶活性升高，提示钙依赖的酯酶对氧磷酶(PON)参与了毛果芸香碱的水解酶活性。为了验证这一假说，用本研究中建立的重组人PON1、PON2和PON3测定了匹罗卡品水解酶的活性，结果表明只有PON1具有匹罗卡品水解酶活性。利用重组人PON1 192Q和192R以及50名志愿者的血浆，分析了PON1基因(Q192R)多态性对匹罗卡品水解酶活性的影响。结果表明，重组PON1 192R的催化效率明显高于PON1 192Q。在人血浆中，R/R基因型的活性(117.0+/-25.2pmol.分钟(-1)。Mu L(-1，n=23)显著高于Q/R型和Q/Q型(97.3+/-21.0pmol)。分钟(-1)。Mu L(-1)，n=20和90.4+/-26.2pmo.分钟(-1)。穆L(-1)，n=7)。提示该基因多态性对毛果芸香碱水解酶活性有影响。在本研究中，我们发现人PON1是影响匹罗卡品水解酶催化效率的主要酶。
Pilocarpine has been widely used in ophthalmic preparations for the treatment of glaucoma and in oral preparations for the treatment of radiation-induced xerostomia and Sjogren syndrome. The major metabolic pathways of pilocarpine in human are hydrolysis and hydroxylation. It was found that CYP2A6 is responsible for the 3-hydroxylation, but the enzymes responsible for the hydrolysis have not been characterized. In this study, we attempted to identify esterases responsible for pilocarpine hydrolysis. Pilocarpine hydrolase activities in human liver microsomes and plasma were stimulated by the addition of CaCl(2), suggesting that the calcium-dependent esterase, paraoxonase (PON), was responsible for pilocarpine hydrolysis. To confirm this hypothesis, the pilocarpine hydrolase activity was measured using the recombinant human PONs (PON1, PON2, and PON3) established in this study, and the result was that only PON1 showed pilocarpine hydrolase activity. The effect of PON1 polymorphism (Q192R) on pilocarpine hydrolase activity was analyzed using recombinant human PON1 192Q and 192R and human plasma from 50 volunteers. The results showed that recombinant PON1 192R revealed significantly higher catalytic efficiency than PON1 192Q. In human plasma, the activity of the R/R genotype (117.0 +/- 25.2 pmol . min(-1) . mu l(-1), n = 23) was significantly higher than those of the Q/R and Q/Q genotypes (97.3 +/- 21.0 pmol . min(-1) . mu l(-1), n = 20 and 90.4 +/- 26.2 pmol . min(-1) . mu l(-1), n = 7, respectively). It is suggested that this polymorphism affects pilocarpine hydrolase activity. In this study, we found that human PON1 is the major enzyme for the catalytic efficiency of pilocarpine hydrolysis.