The unique hydrogen bonded water in the reduced form of Clostridium pasteurianum rubredoxin and its possible role in electron transfer.
The unique hydrogen bonded water in the reduced form of Clostridium pasteurianum rubredoxin and its possible role in electron transfer.
复制标题
巴氏梭菌红氧还蛋白还原形式中独特的氢键水及其在电子转移中的可能作用。
DOI：
10.1007/s00775-004-0542-3
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Kang,ChulHee
中科院分区：
文献类型：
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作者：
Park,IlYeong;Youn,Buhyun;Harley,JillL;Eidsness,MarlyK;Smith,Eugene;Ichiye,Toshiko;Kang,ChulHee
红氧还蛋白是一种参与氧化还原反应的小铁硫（FeS4）蛋白。Leu41靠近铁硫中心的侧链有两个构象，我们之前提出在电子转移过程中充当水分子的门。为了确定残基41在电子转移中的作用，构建了巴氏梭菌的[L41A]突变体，并在两种氧化态下结晶。尽管该蛋白中缺乏门链，但还原的[L41A]红霉素的结构显示出与还原的野生型红霉素相同位置的特定水分子。相比之下，野生型和[L41A]氧化态的红霉素在这个位置都没有水分子。[L41A]突变体的还原电位比野生型高出约50 mV。基于这些观察，我们提出Cys9的s - γ周围的位点作为电子受体的端口。最后，还原后的红氧还蛋白的Fe-S距离扩大，而半胱氨酸的s - γ与主酰胺氮之间的氢键与氧化产物相比缩短。Fe(II)/Fe（III）跃迁中的这种小的结构扰动与小的能量差密切相关，这在有效的电子转移剂中是重要的。
Rubredoxin is a small iron-sulfur (FeS4) protein involved in oxidation–reduction reactions. The side chain of Leu41 near the iron-sulfur center has two conformations, which we suggested previously serve as a gate for a water molecule during the electron transfer process. To establish the role of residue 41 in electron transfer, an [L41A] mutant ofClostridium pasteurianumrubredoxin was constructed and crystallized in both oxidation states. Despite the lack of the gating side chain in this protein, the structure of the reduced [L41A] rubredoxin reveals a specific water molecule in the same position as observed in the reduced wild-type rubredoxin. In contrast, both the wild-type and [L41A] rubredoxins in the oxidized state do not have water molecules in this location. The reduction potential of the [L41A] variant was ~50 mV more positive than wild-type. Based on these observations, it is proposed that the site around the Sγ of Cys9 serves as a port for an electron acceptor. Lastly, the Fe–S distances of the reduced rubredoxin are expanded, while the hydrogen bonds between Sγ of the cysteines and the backbone amide nitrogens are shortened compared to its oxidized counterpart. This small structural perturbation in the Fe(II)/Fe(III) transition is closely related to the small energy difference which is important in an effective electron transfer agent.