Oxygen Sensitivity of Mitochondrial Reactive Oxygen Species Generation Depends on Metabolic Conditions
Oxygen Sensitivity of Mitochondrial Reactive Oxygen Species Generation Depends on Metabolic Conditions
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DOI：
10.1074/jbc.m809512200
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发表时间：
2009-06-12
影响因子：
4.8
通讯作者：
Brookes, Paul S.
中科院分区：
文献类型：
--
作者：
Hoffman, David L.;Brookes, Paul S.
活性氧（ROS）的线粒体生成在许多细胞信号传导途径中起着核心作用，但争论仍然围绕其受底物可用性、[O-2]和代谢状态等因素的调节。以前，我们表明，在孤立的线粒体呼吸琥珀酸，ROS的产生是一个双曲线函数的[O-2]。在目前的研究中，我们使用了各种各样的底物和抑制剂来探测在不同代谢条件下线粒体ROS产生的O-2敏感性。根据这些数据，线粒体内推定ROS生成位点的O-2表观Km估计如下：复合物I黄素位点、复合物I电子回流、复合物IIIQ（O）位点和电子转移黄素蛋白醌氧化还原酶β-氧化分别为0.2、0.9、2.0和5.0 μ M O-2。在不同的[O-2]条件下，还观察到呼吸抑制剂对ROS生成的不同影响。基于这些数据，我们假设，在生理[O-2]，复合物I是ROS的重要来源，而电子转移黄素蛋白醌氧化还原酶可能只有助于ROS的产生在非常高的[O-2]。此外，我们认为，以前的差异分配抑制剂对ROS的影响可能是由于实验[O-2]的差异。最后，数据集（见补充材料）可能是有用的线粒体代谢的数学建模。
The mitochondrial generation of reactive oxygen species (ROS) plays a central role in many cell signaling pathways, but debate still surrounds its regulation by factors, such as substrate availability, [O-2] and metabolic state. Previously, we showed that in isolated mitochondria respiring on succinate, ROS generation was a hyperbolic function of [O-2]. In the current study, we used a wide variety of substrates and inhibitors to probe the O-2 sensitivity of mitochondrial ROS generation under different metabolic conditions. From such data, the apparent K-m for O-2 of putative ROS-generating sites within mitochondria was estimated as follows: 0.2, 0.9, 2.0, and 5.0 mu M O-2 for the complex I flavin site, complex I electron backflow, complex IIIQ(O) site, and electron transfer flavoprotein quinone oxidoreductase of beta-oxidation, respectively. Differential effects of respiratory inhibitors on ROS generation were also observed at varying [O-2]. Based on these data, we hypothesize that at physiological [O-2], complex I is a significant source of ROS, whereas the electron transfer flavoprotein quinone oxidoreductase may only contribute to ROS generation at very high [O-2]. Furthermore, we suggest that previous discrepancies in the assignment of effects of inhibitors on ROS may be due to differences in experimental [O-2]. Finally, the data set (see supplemental material) may be useful in the mathematical modeling of mitochondrial metabolism.