A comparison of Fe 4 S 4 clusters in high-potential iron protein and in ferredoxin.
A comparison of Fe 4 S 4 clusters in high-potential iron protein and in ferredoxin.
复制标题
高电位铁蛋白和铁氧还蛋白中 Fe 4 S 4 簇的比较。
DOI：
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发表时间：
1972
影响因子：
11.1
通讯作者：
L. H. Jensen
中科院分区：
文献类型：
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作者：
C. Carter;J. Kraut;S. Freer;R. A. Alden;L. Sieker;E. Adman;L. H. Jensen
氧化的（HP（ox））和还原的（HP（red））高电位铁蛋白以及氧化的铁氧还蛋白（Fd（ox））的结构已经通过与应用于蛋白质红氧还蛋白的方法类似的方法在2.0-A分辨率下部分精制[Watenpaugh，K. D、锡克湖C.的方法，赫里奥特&詹森，L. H. 1971年：冷泉港会议。定量36，359-367]。HP（红色）和Fd（ox）Fe（4）S（4）（*）簇中的平均键长和键角相同，在每个平均值的均方根（rms）偏差内。两种HiPIP氧化态的初步比较表明，HP（ox）簇在几何上类似于HP（red）簇，但在某些维度上小0.1-0.2 A。HiPIP和铁氧还蛋白簇的几何形状也与最近报道的合成类似物的几何形状几乎相同[Herskovitz，T.，阿弗里尔，B。一、霍尔姆河一、Ibers，J. A.，菲利普斯，W. D. & Wother，J. F.（1972）Proc. Nat. Acad. Sci. USA 69，2437-2441]。由HiPIP和铁氧还蛋白电极电位之间的巨大差异所呈现的明显矛盾可以通过假设Fe（4）S（4）（*）簇具有不是两个而是三个氧化态来解决。完全氧化的（HP（ox））和完全还原的（Fd（red））团簇是顺磁性的，并且中间状态是自旋配对的[Tsibris，J. C. M. Woody，R. W. 04 The Dog（1970）Rev.5，417-458]。这一假设得到了结构和光谱证据的支持，即HP（red）和Fd（ox）中都存在“成对自旋”状态。
The structures of both oxidized (HP(ox)) and reduced (HP(red)) high-potential iron protein and of oxidized ferredoxin (Fd(ox)) have been partially refined at 2.0-A resolution by methods similar to those applied to the protein rubredoxin [Watenpaugh, K. D., Sieker, L. C., Herriott, J. R. & Jensen, L. H. (1971) Cold Spring Harbor Symp. Quant. Biol. 36, 359-367]. Average bond lengths and angles in the HP(red) and Fd(ox) Fe(4)S(4) (*) clusters are the same to within the root-mean square (rms) deviation of each mean value. A preliminary comparison of the two HiPIP oxidation states indicates that the HP(ox) cluster is geometrically similar to the HP(red) cluster, but that it is smaller by 0.1-0.2 A in certain dimensions. The HiPIP and ferredoxin cluster geometry is also nearly identical to that reported recently for a synthetic analog [Herskovitz, T., Averill, B. A., Holm, R. A., Ibers, J. A., Phillips, W. D. & Weither, J. F. (1972) Proc. Nat. Acad. Sci. USA 69, 2437-2441]. An apparent paradox presented by the large difference between the HiPIP and ferredoxin electrode potentials can be resolved by the assumption that the Fe(4)S(4) (*) cluster has not two but three oxidation states. The fully oxidized (HP(ox)) and fully reduced (Fd(red)) clusters are paramagnetic, and the intermediate state is spin-paired [Tsibris, J. C. M. and Woody, R. W. (1970) Coord. Chem. Rev. 5, 417-458]. This hypothesis is supported by structural and spectroscopic evidence that the "paired-spin" state exists in both HP(red) and Fd(ox).