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在ribonucleotide还原酶R2的二铁 (II) 活性位点的可变协调几何学
Walter C Voegtli1, Monika Sommerhalter, Lana Saleh
1Departments of Biochemistry, Molecular Biology, and Cell Biology and of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
Journal of the American Chemical Society
|December 18, 2003
概括
研究人员研究了来自大肠杆菌核糖核酸减少酶的不同R2蛋白的结构. 他们发现,铁浸泡的R2结构与减少的形式不同,为氧激活机制提供了新的见解.
科学领域:
- 生物化学 生物化学
- 结构生物学 结构生物学
- 酶学 是一种酶学.
背景情况:
- 大肠杆菌核糖核酸减少酶的R2子单元对于DNA合成至关重要.
- 它含有二铁中心,对于产生氨基基基是必不可少的.
- 了解二铁 (II) 状态是阐明氧激活的关键.
研究的目的:
- 在生理条件下确定R2的反应物二铁 (II) 形式的结构.
- 为了研究铁浸的R2和化学/光降解的R2.2之间的结构差异.
- 为氧气激活机制研究提供与光谱学发现一致的结构数据.
主要方法:
- 在中性pH下注入Fe (II) 离子到Apo R2蛋白质 (野生型,R2-D84E,R2-D84E/W48F) 的晶体中.
- 进行X射线晶体学以确定所产生的不同R2状态的结构.
- 在中性pH下获得的结构与在较低pH下先前确定的结构进行比较.
主要成果:
- 铁浸的不同质R2-wt和R2-D84E的结构与减少的形式相比,显示出不同的活性部位几何形状.
- R2-wt和R2-D84E/W48F的结构在中性和低pH之间是相似的,表明pH不是观察到的差异的唯一因素.
- 确定的结构更好地与循环二元化和磁性循环二元化光谱数据保持一致.
结论:
- 铁浸的R2中的二铁 (II) 中心的结构与之前报告的减少形式有很大的不同.
- 这些发现挑战了现有的模型,并为了解O(2) 激活机制提供了新的结构性起点.
- 这项研究强调了在生理学上相关条件下结构确定的重要性.
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