Kinetic model of the inhibition of respiration by endogenous nitric oxide in intact cells
Kinetic model of the inhibition of respiration by endogenous nitric oxide in intact cells
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DOI：
10.1016/j.bbabio.2010.01.033
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发表时间：
2010-05-01
影响因子：
4.3
通讯作者：
Cadenas, Susana
中科院分区：
文献类型：
--
作者：
Aguirre, Enara;Rodriguez-Juarez, Felix;Cadenas, Susana
一氧化氮（NO）通过降低细胞色素c氧化酶（CcO）对氧的表观亲和力来抑制线粒体呼吸。使用iNOS转染的HEK 293细胞，以实现调节细胞内NO的产生，我们确定了NO和O-2的浓度和线粒体O-2的消耗，通过高分辨率呼吸测定法在一个范围内的O-2浓度下降到纳摩尔。呼吸抑制NO是可逆的，完全去除NO恢复细胞呼吸高于其常规参考值。即使在高NO浓度下也观察到呼吸，并且IC 50对[O-2]的依赖性表现出特征性但令人困惑的抛物线形状;这两个特征都意味着CcO被NO保护免于完全失活，并且可能是生理相关的。我们提出了一个动力学模型CcO抑制NO，有效地预测实验确定的呼吸在生理O-2和NO浓度和缺氧，并准确地预测呼吸反应下高氧。该模型调用竞争性和非竞争性抑制NO的还原和氧化形式的CcO，分别结合，并建议从还原CcO的NO的解离可能涉及其O-2依赖性氧化。这也解释了IC 50对O-2浓度的非线性依赖性，以及c（50）作为NO浓度的函数的双曲线增加。(C)2010 Elsevier B. V.保留所有权利。
Nitric oxide (NO) inhibits mitochondrial respiration by decreasing the apparent affinity of cytochrome c oxidase (CcO) for oxygen. Using iNOS-transfected HEK 293 cells to achieve regulated intracellular NO production, we determined NO and O-2 concentrations and mitochondrial O-2 consumption by high-resolution respirometry over a range of O-2 concentrations down to nanomolar. Inhibition of respiration by NO was reversible, and complete NO removal recovered cell respiration above its routine reference values. Respiration was observed even at high NO concentrations, and the dependence of IC50 on [O-2] exhibits a characteristic but puzzling parabolic shape; both these features imply that CcO is protected from complete inactivation by NO and are likely to be physiologically relevant. We present a kinetic model of CcO inhibition by NO that efficiently predicts experimentally determined respiration at physiological O-2 and NO concentrations and under hypoxia, and accurately predicts the respiratory responses under hyperoxia. The model invokes competitive and uncompetitive inhibition by binding of NO to the reduced and oxidized forms of CcO, respectively, and suggests that dissociation of NO from reduced CcO may involve its O-2-dependent oxidation. It also explains the non-linear dependence of IC50 on O-2 concentration, and the hyperbolic increase of c(50) as a function of NO concentration. (C) 2010 Elsevier B.V. All rights reserved.