Spectroscopic approaches to elucidating novel iron-sulfur chemistry in the "Radical-SAM" protein superfamily
Spectroscopic approaches to elucidating novel iron-sulfur chemistry in the "Radical-SAM" protein superfamily
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DOI：
10.1021/ic0484811
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发表时间：
2005-02-21
影响因子：
4.6
通讯作者：
Broderick, JB
中科院分区：
文献类型：
--
作者：
Walsby, CJ;Ortillo, D;Broderick, JB
电子顺磁共振（EPR），电子-核双共振（ENDOR），穆斯堡尔谱和其他物理方法提供了重要的新见解自由基SAM超家族的蛋白质，使用铁硫簇和S-腺苷甲硫氨酸引发H原子提取反应。这种显著的化学反应涉及到产生活性极高的5 '-脱氧腺苷自由基，这是B-12依赖性反应中使用的相同自由基中间体。虽然早期的猜测集中在自由基SAM反应中的有机金属中间体的可能性，但目前的证据表明，新的化学物质涉及位点差异化的[4Fe-4S]簇。这篇论坛文章的重点是自由基SAM超家族的一个成员，丙酮酸甲酸裂解酶激活酶，以及物理方法，主要是EPR和ENDOR光谱，如何有助于我们理解其结构和机制。新的ENDOR数据支持SAM的甲硫氨酸部分与[4Fe-4S]（2+/+）簇的独特位点的配位。
Electron paramagnetic resonance (EPR), electron-nuclear double resonance (ENDOR), and Mossbauer spectroscopies and other physical methods have provided important new insights into the radical-SAM superfamily of proteins, which use iron-sulfur clusters and S-adenosylmethionine to initiate H atom abstraction reactions. This remarkable chemistry involves the generation of the extremely reactive 5'-deoxyadenosyl radical, the same radical intermediate utilized in B-12-dependent reactions. Although early speculation focused on the possibility of an organometallic intermediate in radical-SAM reactions, current evidence points to novel chemistry involving a site-differentiated [4Fe-4S] cluster. The focus of this forum article is on one member of the radical-SAM superfamily, pyruvate formate-lyase activating enzyme, and how physical methods, primarily EPR and ENDOR spectroscopies, are contributing to our understanding of its structure and mechanism. New ENDOR data supporting coordination of the methionine moiety of SAM to the unique site of the [4Fe-4S](2+/+) cluster are presented.