Monitoring of Biological One-Electron Reduction by 19F NMR Using Hypoxia Selective Activation of an 19F-Labeled Indolequinone Derivative
Monitoring of Biological One-Electron Reduction by 19F NMR Using Hypoxia Selective Activation of an 19F-Labeled Indolequinone Derivative
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DOI：
10.1021/ja904953b
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发表时间：
2009-11-11
影响因子：
15
通讯作者：
Nishimoto, Sei-ichi
中科院分区：
文献类型：
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作者：
Tanabe, Kazuhito;Harada, Hiroshi;Nishimoto, Sei-ichi
利用F-19 NMR对氟标记吲哚醌衍生物（IQ-F）的生物还原进行了表征，以定量了解其分子结构。F-19 NMR中的化学位移变化允许监测IQ-F的酶促还原。缺氧处理后的IQ-F与NADPH：细胞色素P450还原酶，IQ-F被激活，通过催化单电子还原，释放壬基-叔丁醇（F-OH），而F-OH的形成显着抑制有氧条件下。在表达NADPH：细胞色素P450还原酶的A549细胞内发生了类似的IQ-F低氧选择性还原。动力学分析也进行了建议的反应机理。分子氧轻微地阻止IQ-F与还原酶的结合，而净反应速率由于IQ-F的单电子还原产生的半醌阴离子自由基中间体的氧化而降低。通过F-19快速自旋回波成像IQ-F的消失和F-OH的出现，从而通过MR成像可视化IQ-F的缺氧选择性降低。
Biological reduction of fluorine-labeled indolequinone derivative (IQ-F) was characterized by F-19 NMR for quantitative molecular understanding. The chemical shift change in F-19 NMR allowed monitoring of the enzymatic reduction of IQ-F. Upon hypoxic treatment of IQ-F with NADPH:cytochrome P450 reductase, IQ-F was activated via catalytic one-electron reduction to release nonafluoro-tert-butyl alcohol (F-OH), while the formation of F-OH was significantly suppressed under aerobic conditions. Similar hypoxia-selective reduction of IQ-F occurred within A549 cells, which expresses NADPH:cytochrome P450 reductase. The kinetic analysis was also performed to propose a reaction mechanism. The molecular oxygen slightly prevents the binding of IQ-F to reductase, while the rate of net reaction was decreased due to oxidation of a semiquinone anion radical intermediate generated by one-electron reduction of IQ-F. The disappearance of IQ-F and appearance of F-OH were imaged by F-19 fast spin echo, thus visualizing the hypoxia-selective reduction of IQ-F by means of MR imaging.