[4Fe-4S]簇缺失的棕色固氮菌铁氧化还原蛋白I：一种新型的3Fe铁硫蛋白。
[4Fe-4S]-cluster-depleted Azotobacter vinelandii ferredoxin I: a new 3Fe iron-sulfur protein.
作者信息
Stephens P J, Morgan T V, Devlin F, Penner-Hahn J E, Hodgson K O, Scott R A, Stout C D, Burgess B K
出版信息
Proc Natl Acad Sci U S A. 1985 Sep;82(17):5661-5. doi: 10.1073/pnas.82.17.5661.
Fe(CN)6(-3) oxidation of the aerobically isolated 7Fe Azotobacter vinelandii ferredoxin I, (7Fe)FdI, is a degradative reaction. Destruction of the [4Fe-4S] cluster occurs first, followed by destruction of the [3Fe-3S] cluster. At a Fe(CN)6(-3)/(7Fe)FdI concentration ratio of 20, the product is a mixture of apoprotein and protein containing only a [3Fe-3S] cluster, (3Fe)FdI. This protein mixture, after partial purification, has been characterized by absorption, CD, magnetic CD, and EPR and Fe x-ray absorption spectroscopies. EPR and magnetic CD spectra provide strong evidence that the [3Fe-3S] cluster in (3Fe)FdI is essentially identical in structure to that in (7Fe)FdI. Analysis of the extended x-ray absorption fine structure (EXAFS) of (3Fe)FdI finds Fe scattering at an average Fe...Fe distance of approximately equal to 2.7 A. The structure of the oxidized [3Fe-3S] cluster in solutions of oxidized (3Fe)FdI, and, by extension, of oxidized (7Fe)FdI, is thus different from that obtained by x-ray crystallography on oxidized (7Fe)FdI. Possible interpretations of this result are discussed.
对需氧条件下分离得到的固氮菌铁氧化还原蛋白I（7Fe）FdI进行Fe(CN)₆⁻³氧化，这是一个降解反应。首先发生[4Fe - 4S]簇的破坏，随后是[3Fe - 3S]簇的破坏。当Fe(CN)₆⁻³与（7Fe）FdI的浓度比为20时，产物是脱辅基蛋白和仅含一个[3Fe - 3S]簇的蛋白（3Fe）FdI的混合物。该蛋白混合物经过部分纯化后，已通过吸收光谱、圆二色光谱、磁圆二色光谱、电子顺磁共振光谱和铁X射线吸收光谱进行了表征。电子顺磁共振光谱和磁圆二色光谱提供了有力证据，表明（3Fe）FdI中的[3Fe - 3S]簇在结构上与（7Fe）FdI中的基本相同。对（3Fe）FdI的扩展X射线吸收精细结构（EXAFS）分析发现，铁散射的平均Fe...Fe距离约等于2.7 Å。因此，氧化态（3Fe）FdI溶液中氧化态[3Fe - 3S]簇的结构，以及由此推断的氧化态（7Fe）FdI中氧化态[3Fe - 3S]簇的结构，与通过对氧化态（7Fe）FdI进行X射线晶体学分析得到的结构不同。本文讨论了该结果的可能解释。
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