Redox-dependent sodium binding by the Na+-Translocating NADH:: Quinone oxidoreductase from Vibrio harveyi
Redox-dependent sodium binding by the Na+-Translocating NADH:: Quinone oxidoreductase from Vibrio harveyi
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DOI：
10.1021/bi700440w
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发表时间：
2007-09-04
期刊：
影响因子：
2.9
通讯作者：
Verkhovsky, Michael I.
中科院分区：
文献类型：
--
作者：
Bogachev, Alexander V.;Bertsova, Yulia V.;Verkhovsky, Michael I.
利用Na-23核磁化弛豫特性研究了哈氏弧菌（Vibrioharveyi，NQR）中Na+转位型NADH：醌氧化还原酶（NQR）的钠结合特性。Na+对氧化酶的解离常数为24 mM，对还原酶的解离常数约为30 μ M。NQR对钠离子的亲和力的这种大的（3个数量级）氧化还原依赖性表明，分子机制被设计为使用氧化还原能量的下降来产生电化学钠梯度。通过在2 mM Na+下Na-23 NMR信号的线宽变化监测的NQR的氧化还原滴定显示，对于E-m约为-300 mV（相对于SHE）的单电子载体，酶对钠离子的亲和力遵循能斯特定律。这些数据表明，能量守恒NQR涉及的机制调节离子亲和力的氧化还原状态的酶的氧化还原辅因子。
Relaxation characteristics of the Na-23 nuclei magnetization were used to determine the sodium-binding properties of the Na+-translocating NADH:quinone oxidoreductase from Vibrio harveyi (NQR). The dissociation constant of Na+ for the oxidized enzyme was found to be 24 mM and for the reduced enzyme about 30 mu M. Such large (3 orders in magnitude) redox dependence of the NQR affinity to sodium ions shows that the molecular machinery was designed to use the drop in redox energy for creating an electrochemical sodium gradient. Redox titration of NQR monitored by changes in line width of the Na-23 NMR signal at 2 mM Na+ showed that the enzyme affinity to sodium ions follows the Nernst law for a one-electron carrier with E-m about -300 mV (vs SHE). The data indicate that energy conservation by NQR involves a mechanism modulating ion affinity by the redox state of an enzyme redox cofactor.