A kinetic model linking protein conformational motions, interflavin electron transfer and electron flux through a dual-flavin enzyme-simulating the reductase activity of the endothelial and neuronal nitric oxide synthase flavoprotein domains.
A kinetic model linking protein conformational motions, interflavin electron transfer and electron flux through a dual-flavin enzyme-simulating the reductase activity of the endothelial and neuronal nitric oxide synthase flavoprotein domains.
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通过双黄素酶将蛋白质构象运动、黄素间电子转移和电子通量联系起来的动力学模型，模拟内皮和神经元一氧化氮合酶黄素蛋白结构域的还原酶活性。
DOI：
10.1111/j.1742-4658.2011.08310.x
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
Stuehr,DennisJ
中科院分区：
文献类型：
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作者：
Haque,MohammadM;Kenney,Claire;Tejero,Jesús;Stuehr,DennisJ
NADPH依赖性双黄素酶在许多氧化还原反应中提供电子，尽管负责调节其电子通量的机制仍不清楚。我们最近提出了一个四态动力学模型，该模型将通过双黄素酶的电子通量与其黄素间电子转移速率和FMN结构域构象运动联系起来[Stuehr DJet等人。（2009）[6]FEBS J276，3959-3974]。在本研究中，我们运行了动力学模型的计算机模拟，以确定它是否可以通过神经元和内皮型一氧化氮合酶黄素蛋白（神经元型一氧化氮合酶和内皮型一氧化氮合酶的还原酶结构域，分别）拟合实验确定的，前稳态和稳态的电子通量的痕迹细胞色素。我们发现，动力学模型准确地拟合实验数据。模拟估计的合奏速率的interflavin电子转移和FMN结构域的构象运动的还原酶结构域的神经元型一氧化氮合酶和内皮型一氧化氮合酶，提供了最小速率边界值，并预测的浓度的四种酶的催化过程中循环。本研究的结果表明，interflavin的电子转移和FMN域构象运动的速率是平衡的，这两个过程可能会限制通过酶的电子通量。这样的平衡将允许稳健的电子通量，同时将黄素间电子转移和FMN结构域构象运动的速率保持在相对低的水平。
NADPH‐dependent dual‐flavin enzymes provide electrons in many redox reactions, although the mechanism responsible for regulating their electron flux remains unclear. We recently proposed a four‐state kinetic model that links the electron flux through a dual‐flavin enzyme to its rates of interflavin electron transfer and FMN domain conformational motion [Stuehr DJet al.(2009)[6]FEBS J276, 3959–3974]. In the present study, we ran computer simulations of the kinetic model to determine whether it could fit the experimentally‐determined, pre‐steady‐state and steady‐state traces of electron flux through the neuronal and endothelial NO synthase flavoproteins (reductase domains of neuronal nitric oxide synthase and endothelial nitric oxide synthase, respectively) to cytochromec. We found that the kinetic model accurately fitted the experimental data. The simulations gave estimates for the ensemble rates of interflavin electron transfer and FMN domain conformational motion in the reductase domains of neuronal nitric oxide synthase and endothelial nitric oxide synthase, provided the minimum rate boundary values, and predicted the concentrations of the four enzyme species that cycle during catalysis. The findings of the present study suggest that the rates of interflavin electron transfer and FMN domain conformational motion are counterbalanced such that both processes may limit electron flux through the enzymes. Such counterbalancing would allow a robust electron flux at the same time as keeping the rates of interflavin electron transfer and FMN domain conformational motion set at relatively slow levels.