核糖核酸还原酶中间体X的质子化氧联结体的鉴定
Muralidharan Shanmugam1, Peter E Doan, Nicholas S Lees
1Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
Journal of the American Chemical Society
|February 18, 2009
概括
这项研究证实,中间X,是核酸减少酶的前体,含有终端水联体和mu-oxo桥,但没有mu-hydroxo桥. 这些发现适用于该酶的野生类型和突变形式.
科学领域:
- 生物化学 生物化学
- 生物有机化学 生物有机化学
- 频谱学是一种光谱学方法.
背景情况:
- 介质X是埃舍里希亚大肠杆菌核糖核酸减少酶 (RNR) 中不同基-铁基辅因子的直接前体.
- 之前使用电子核双共振 (ENDOR) 的研究提出了中介X的[{H}{x}{O}{Fe}{III}{O}{Fe}{IV}}]片段,缺少mu-hydroxo桥.
- 关于介质X的无机核心结构,已经提出了相互矛盾的模型.
研究的目的:
- 重新检查介质X的Fe (III) /Fe (IV) 集群中的氧联体的质子化状态.
- 使用 (2) H脉冲ENDOR光谱直接探测可交换的质子.
- 为了澄清关于中间X的无机核心的结构差异.
主要方法:
- 使用了先进的35GHz脉冲ENDOR光谱学.
- 采用 (2) H 脉冲的 ENDOR 来研究可交换的质子在氧联体上.
- 进行了 (14)N ENDOR测量对西提连接剂的测量.
主要成果:
- 证实了在中间X.中存在一个与Fe (III) 结合的终端水联体 (H (x) O).
- 没有观察到任何光谱特征表明桥梁基质子.
- 证明这些发现在野生类型和Y122F-β2 RNR突变中一致.
- 检测到两种变体之间的终端氧质子特性或基结合体结合没有差异.
结论:
- 介质X包含一个终端水联体和一个或两个mu-oxo桥,绝对不包括一个mu-hydroxo桥.
- 结构性结论是强大的,适用于野生类型和Y122F-β2 RNR.
- 这项研究解决了关于中间X的无机核心的结构模两可.
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