The reduced [2Fe-2S] clusters in adrenodoxin and Arthrospira platensis ferredoxin share spin density with protein nitrogens, probed using 2D ESEEM
The reduced [2Fe-2S] clusters in adrenodoxin and Arthrospira platensis ferredoxin share spin density with protein nitrogens, probed using 2D ESEEM
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DOI：
10.1039/b904597j
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发表时间：
2009-01-01
影响因子：
3.3
通讯作者：
Huettermann, Juergen
中科院分区：
文献类型：
--
作者：
Dikanov, Sergei A.;Samoilova, Rimma I.;Huettermann, Juergen
我们使用 X 波段 ESEEM 研究了肾上腺氧还蛋白和钝节节旋藻铁氧还蛋白中还原的 [2Fe-2S] 簇。通过使用 2D 方法 (HYSCORE)，我们表明该簇参与与每个蛋白质中的多个氮的弱磁性相互作用。尽管各个交叉峰的形状和方向依赖性存在显着差异，但这两种蛋白质的主要光谱特征可归因于具有类似于 1.1 和类似于 0.70 MHz 的相似超精细耦合的两个肽氮（N1 和 N2）。确定的耦合代表通过氢键桥或半胱氨酸配体的共价键转移到这些氮的还原簇的不配对自旋密度的一小部分（0.0003-0.0005）。 HYSCORE 谱的模拟使我们能够估计 N1 和 N2 的核四极张量在 g 张量坐标系中的方向。通过将磁共振数据与氧化蛋白质的晶体结构进行比较，已经在蛋白质环境中确定了 N1 和 N2 最有可能发挥作用的候选者。使用两种氧化还原状态下相关蛋白质的可用结构分析了氧化还原相关的结构变化对 ESEEM 数据的可能影响。
We have used X-band ESEEM to study the reduced [2Fe-2S] cluster in adrenodoxin and Arthrospira platensis ferredoxin. By use of a 2D approach (HYSCORE), we have shown that the cluster is involved in weak magnetic interactions with several nitrogens in each protein. Despite substantial differences in the shape and orientational dependence of individual cross-peaks, the major spectral features in both proteins are attributable to two peptide nitrogens (N1 and N2) with similar hyperfine couplings similar to 1.1 and similar to 0.70 MHz. The couplings determined represent a small fraction (0.0003-0.0005) of the unpaired spin density of the reduced cluster transferred to these nitrogens over H-bond bridges or the covalent bonds of cysteine ligands. Simulation of the HYSCORE spectra has allowed us to estimate the orientation of the nuclear quadrupole tensors of N1 and N2 in the g-tensor coordinate system. The most likely candidates for the role of N1 and N2 have been identified in the protein environment by comparing magnetic-resonance data with crystallographic structures of the oxidized proteins. A possible influence of redox-linked structural changes on ESEEM data is analyzed using available structures for related proteins in two redox states.