在Fe2 (III/IV) 中介物X中A 2.8 Å的Fe-Fe分离,来自大肠杆菌的核糖核酸还原酶
Laura M K Dassama1, Alexey Silakov, Courtney M Krest
1Departments of †Chemistry and ‡Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Journal of the American Chemical Society
|October 8, 2013
概括
研究人员改进了在核糖核酸减少酶 (RNR) 酶中含铁的关键中间体 (X) 的结构. 这种对Fe-Fe距离的更好理解阐明了RNR如何启动DNA合成和修复.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 生物有机化学 生物有机化学
背景情况:
- 一级Ia核糖核酸减少酶 (RNRs) 是DNA合成和修复的必要酶.
- 这些酶利用一种独特的μ-oxo-Fe2 ((III/III) /tyrosyl基因辅因子来降低基质.
- 一种高价值的铁中间体,称为X,对于激活辅因子至关重要.
研究的目的:
- 解决中间X的Fe-Fe距离的实验模型和计算模型之间的差异.
- 改进中间X的Fe2 (III/IV) 集群的结构特征.
- 提供有关Ia类RNR产生的铁基生成机制的见解.
主要方法:
- 使用扩展的X射线吸收细结构 (EXAFS) 光谱法来确定Fe-Fe分离.
- 开发了一种使用化物和化物脱酶的现场方法,以在更高度 (~2.0mM) 产生中间X.
- 将实验EXAFS数据与铁硫团的计算和合成模型进行比较.
主要成果:
- 确定了中间X的2.78 Å的Fe-Fe分离,解决了之前的差异.
- 这一距离与 (μ-oxo) 2-Fe2 ((III/IV) 核心结构一致,使实验和计算结果一致.
- 这种精细的结构为了解Y122基因形成的机制提供了基础.
结论:
- 在中间X中修订的Fe-Fe距离使实验数据与理论模型相协调.
- 这种结构改进提高了我们对Ia类RNRs激活机制的理解.
- 这些发现有助于更广泛地了解高价值非血红素铁酶机制.
相关概念视频
01:46Electron Transport Chain: Complex I and II
The mitochondrial electron transport chain (ETC) is the main energy generation system in the eukaryotic cells. However, mitochondria also produce cytotoxic reactive oxygen species (ROS) due to the large electron flow during oxidative phosphorylation. While Complex I is one of the primary sources of superoxide radicals, ROS production by Complex II is uncommon and may only be observed in cancer cells with mutated complexes.
ROS generation is regulated and maintained at moderate levels necessary...
ROS generation is regulated and maintained at moderate levels necessary...
01:43Electron Transport Chain: Complex III and IV
During the electron transport chain, electrons from NADH and FADH2 are first transferred to complexes I and II, respectively. These two complexes then transfer the electrons to ubiquinol, which carries them further to complex III. Complex III passes the electrons across the intermembrane space to Cyt c, which carries them further to complex IV. Complex IV donates electrons to oxygen and reduces it to water. As electrons pass through complexes I, III, and IV, the energy released aids the pumping...
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...