Aldehyde oxidase functions as a superoxide generating NADH oxidase: an important redox regulated pathway of cellular oxygen radical formation.
Aldehyde oxidase functions as a superoxide generating NADH oxidase: an important redox regulated pathway of cellular oxygen radical formation.
复制标题
DOI：
10.1021/bi3000879
复制
发表时间：
2012-04-03
期刊：
影响因子：
2.9
通讯作者：
Zweier JL
中科院分区：
文献类型：
--
作者：
Kundu TK;Velayutham M;Zweier JL
醛氧化酶（AO）是钼羟化酶家族的一员，该家族包括黄嘌呤氧化还原酶（XOR）;然而，其生理底物和功能仍不清楚。此外，关于其在细胞氧化还原应激中的作用知之甚少。利用电子顺磁共振自旋捕集技术研究了AO在NADH氧化产生活性氧（ROS）过程中的作用，以及AO抑制剂对NADH介导的超氧化物（ROS）产生的影响。发现NADH是AO的良好底物，表观Km和Vmax值分别为29μM和12 nmol min−1 mg−1。从 通过细胞色素c还原的代测量，AO的NADH的表观Km和Vmax值分别为11 μM和15 nmol min−1 mg−1。在AO氧化NADH的情况下，≥65%的总电子通量导致 一代联苯碘鎓完全抑制AO介导的 生产确认这发生在FAD现场。这种NADH衍生的抑制剂 在100 μM的浓度下，amidone的抑制作用最强，而150 μM的甲萘醌、雷洛昔芬或β-雌二醇的抑制作用分别为81%、46%和26%。从动力学数据，AO和NADH的水平， 在肝脏和心脏中的产量估计分别为~89和~4 nM/s，远高于在类似条件下对XOR的估计。由于NADH、醛和其他内源性AO底物的普遍分布，预测AO在细胞氧化还原应激和相关疾病发病机制中具有重要作用。
The enzyme aldehyde oxidase (AO) is a member of the molybdenum hydroxylase family that includes xanthine oxidoreductase (XOR); however, its physiological substrates and functions remain unclear. Moreover, little is known about its role in cellular redox stress. Utilizing electron paramagnetic resonance spin trapping we measured the role of AO in the generation of reactive oxygen species (ROS) through the oxidation of NADH, and the effects of inhibitors of AO on NADH-mediated superoxide ( ) generation. NADH was found to be a good substrate for AO with apparent Km and Vmax values of 29μM and 12 nmol min−1 mg−1, respectively. From generation measurements by cytochrome c reduction the apparent Km and Vmax values of NADH for AO were 11 μM and 15 nmol min−1 mg−1, respectively. With NADH oxidation by AO, ≥65% of the total electron flux led to generation. Diphenyleneiodonium completely inhibited AO-mediated production confirming that this occurs at the FAD site. Inhibitors of this NADH-derived generation were studied with amidone the most potent exerting complete inhibition at 100 μM concentration, while 150 μM menadione, raloxifene or β-estradiol led to 81%, 46% or 26% inhibition, respectively. From the kinetic data, the levels of AO and NADH, production was estimated to be ~89 and ~4 nM/s in liver and heart, respectively, much higher than that estimated for XOR under similar conditions. Owing to the ubiquitous distribution of NADH, aldehydes, and other endogenous AO substrates, AO is predicted to have an important role in cellular redox stress and related disease pathogenesis.