MODELS FOR FERREDOXINS - ELECTRONIC-STRUCTURES OF IRON SULFUR CLUSTERS WITH ONE, 2, AND 4 IRON ATOMS
MODELS FOR FERREDOXINS - ELECTRONIC-STRUCTURES OF IRON SULFUR CLUSTERS WITH ONE, 2, AND 4 IRON ATOMS
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DOI：
10.1021/ja00298a004
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发表时间：
1985-01-01
影响因子：
15
通讯作者：
CASE, DA
中科院分区：
文献类型：
--
作者：
NOODLEMAN, L;NORMAN, JG;CASE, DA
X.Alpha的结果。本文报道了模拟Fe-S蛋白质活性中心的各种簇的价键散射波(X.α-VB-Sw)计算：Fe(SR)41-，2-(R=H，CH3)，Fe2S2(SH)42-，3-和Fe4S4(SCH3)42-，3-。重点是各种团簇之间的比较，包括还原时电子分布的变化，从低自旋到高自旋时的变化，以及团簇几何结构的变化。根据穆斯堡尔异构体位移和四极分裂的计算给出了估计值，这导致了对许多实验观测的一致解释。计算预测Fe(桥联S)键比Fe与末端S原子之间的键更强；这具有有趣的结构和光谱意义。在很好的近似下，氧化的4-Fe络合物可以被看作是2个高自旋还原的2-Fe团簇，尽管几何结构不同。讨论了这些结果对解决铁-S蛋白结构-功能问题的一些意义。
Results of X.alpha. valence bond scattered wave (X.alpha.-VB-SW) calculations were reported for a variety of clusters that mimic the active sites in Fe-S proteins: Fe(SR)41-,2- (R = H, CH3), Fe2S2(SH)42-,3-, and Fe4S4(SCH3)42-,3-. Emphasis is placed on comparisons among the various clusters, including changes in the electron distribution upon reduction, upon going from low spin to high spin, and upon changes in cluster geometry. Estimates are presented based on the calculations of Mossbauer isomer shifts and quadrupole splittings, which lead to a consistent account of many experimental observations. The calculations predict the Fe (bridgingg S) bonds to be stronger than those between Fe and the terminal S atoms; this has interesting structural and spectroscopic implications. To a good approximation, the oxidized 4-Fe complex can be viewed as 2 high-spin reduced 2-Fe clusters, despite the differences in geometry. Some of the implications of these results for structure-function problems in Fe-S proteins are discussed.