Flavo-diiron enzymes: nitric oxide or dioxygen reductases?
Flavo-diiron enzymes: nitric oxide or dioxygen reductases?
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DOI：
10.1039/b710047g
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发表时间：
2007-01-01
影响因子：
4
通讯作者：
Kurtz, Donald M., Jr.
中科院分区：
文献类型：
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作者：
Kurtz, Donald M., Jr.
黄素二铁酶是最近公认的非血红素二铁蛋白亚类之一。黄素二铁酶的活性位点由黄素辅因子和组氨酸、谷氨酸、天冬氨酸连接、溶剂桥联的二铁位点的独特并置组成。黄素二铁酶最初被认为具有清除分子氧还原酶 (s-O(2)Rs) 的功能，因为它们能够催化分子氧还原成水，从而保护对空气敏感的细菌和古细菌免受“氧化应激”。然而，遗传和生化证据强烈表明，至少在某些细菌中，黄素二铁酶起到清除一氧化氮还原酶（s-NOR）的作用，催化一氧化氮还原为一氧化二氮，从而防止厌氧生长条件下的“亚硝化应激”。尚未解决的关键问题包括：应该。黄酮二铁酶可分为 s-NOR 和 s-O2R 类别，如果是这样，活性位点的哪些特征可以区分这两种活性？如果不是，活动站点如何容纳和优化这些活动的相对水平？系统研究了几种的结构和催化机制。黄素二铁酶是回答这些问题的一种方法。本文回顾了当前的知识状况和为此取得的进展。
Flavo-diiron enzymes are among the most recently recognized sub-class of non-heme diiron proteins. The active sites of flavo-diiron enzymes consist of a unique juxtaposition of a flavin cofactor and a histidine, glutamate, aspartate-ligated, solvent-bridged diiron site. Flavo-diiron enzymes were initially thought to function as scavenging dioxygen reductases (s-O(2)Rs), based on their ability to catalyze the reduction of dioxygen to water, thus protecting air-sensitive bacteria and archaea against "oxidative stress". However, genetic and biochemical evidence strongly suggests that, at least in some bacteria, flavo-diiron enzymes function as scavenging nitric oxide reductases (s-NORs), catalyzing the reduction of nitric oxide to nitrous oxide, thus, protecting against "nitrosative stress" under anaerobic growth conditions. Key unsettled questions include: should. flavo-diiron enzymes be divided into s-NOR and s-O2R categories, and, if so, what features of the active sites distinguish the two activities? If not, how does the active site accommodate and optimize the relative levels of these activities? Systematic investigations of the structures and catalytic mechanisms of several. flavo-diiron enzymes constitute an approach to answer these questions. The current state of knowledge and progress toward this end is reviewed here.