Continuous-Wave and Pulsed EPR Characterization of the [2Fe-2S](Cys)3(His)1 Cluster in Rat MitoNEET
Continuous-Wave and Pulsed EPR Characterization of the [2Fe-2S](Cys)3(His)1 Cluster in Rat MitoNEET
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DOI：
10.1021/ja903228w
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发表时间：
2009-09-30
影响因子：
15
通讯作者：
Dikanov, Sergei A.
中科院分区：
文献类型：
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作者：
Iwasaki, Toshio;Samoilova, Rimma I.;Dikanov, Sergei A.
哺乳动物mitoNEET可溶性结构域还原[2Fe-2S](Cys)(3)(His)(1)团簇的连续波EPR谱似乎产生了两个相邻团簇电子自旋相互作用的特征，这可以用局部自旋模型来解释。该模型倾向于His87和Cys83配体对最外层铁的还原，这得到了取向选择超精细亚能级相关（HYSCORE）表征的支持，该表征显示了一个来自His87 n- δ配体的强耦合氮，具有超精细耦合（15）a = 8 MHz。N-14和N-15 HYSCORE光谱在（++）象限的对角线附近也表现出至少两个不同的交叉峰，频率类似于2.8和2.4 MHz (N2)，另一个类似于4.0和3.5 MHz (N1)，但没有显示任何类似于先前在Rieske蛋白中看到的1.1-1.4 MHz的较大分裂。对部分N-15(3)- his标记蛋白的进一步分析表明，His87 N-epsilon交叉峰在N-14光谱中产生分解特征（N2），但在N-15光谱中对（++）象限的贡献远小于弱偶联肽氮。这些定量数据可用于哺乳动物mitoNEET [2Fe-2S]簇系统的功能和理论研究。
CW EPR spectra of reduced [2Fe-2S](Cys)(3)(His)(1) clusters of mammalian mitoNEET soluble domain appear to produce features resulting from the interaction of the electron spins of the two adjacent clusters, which can be explained by employing the local spin model. This model favors the reduction of the outermost iron with His87 and Cys83 ligands, which is supported by orientation-selected hyperfine sublevel correlation (HYSCORE) characterization of the uniformly N-15-labeled mitoNEET showing one strongly coupled nitrogen from the His87 N-delta ligand with hyperfine coupling (15)a = 8 MHz. The N-14 and N-15 HYSCORE spectra also exhibit at least two different cross-peaks located near diagonal in the (++) quadrant, with frequencies similar to 2.8 and 2.4 MHz (N2), and the other similar to 4.0 and 3.5 MHz (N1), but did not show any of the larger splitting similar to 1.1-1.4 MHz previously seen with Rieske proteins. Further analysis with partially N-15(3)-His-labeled protein indicates that His87 N-epsilon cross-peaks produce resolved features (N2) in the N-14 spectrum but contribute much less than weakly coupled peptide nitrogen species to the (++) quadrant in the N-15 spectrum. It is suggested that these quantitative data may be used in future functional and theoretical studies on the mammalian mitoNEET [2Fe-2S] cluster system.