Pulsed ELDOR spectroscopy measures the distance between the two tyrosyl dadicals in the R2 subunit of the E. coli ribonucleotide reductase.
Pulsed ELDOR spectroscopy measures the distance between the two tyrosyl dadicals in the R2 subunit of the E. coli ribonucleotide reductase.
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脉冲 ELDOR 光谱测量大肠杆菌核糖核苷酸还原酶 R2 亚基中两个酪氨酰基之间的距离。
DOI：
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发表时间：
2003
影响因子：
15
通讯作者：
J. Stubbe
中科院分区：
文献类型：
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作者：
M. Bennati;Axel Weber;J. Antonic;Deborah L. Perlstein;J. Robblee;J. Stubbe
大肠杆菌核糖核苷酸还原酶 (RNR) 催化核苷二磷酸 (NDP) 转化为脱氧核苷二磷酸 (dNDP)。该 RNR 由两个同源二聚体亚基组成：R1 和 R2。 R1 结合活性位点的 NDP，R2 包含必需的二铁酪氨酰自由基 (Y*) 辅因子。在本文中，我们使用PELDOR（一种检测弱电子-电子偶极耦合的方法）首次直接测量R2每个单体上两个Y*之间的距离。在 R2 的晶体结构中，Y* 被还原为酪氨酸，因此 R2 不活泼。在 R2 中，Y* 相对于蛋白质骨架呈现明确的几何形状，PELDOR 方法允许测量 33.1 +/- 0.2 A 的距离，该距离与结构中每个 R2 单体上每个 Y* 自旋密度分布的质心之间的距离 (32.4 A) 相当。这些实验为溶液中单个 R2 中存在两个 Y* 提供了第一个直接的实验证据。
Escherichia coli ribonucleotide reductase (RNR) catalyzes the conversion of nucleoside diphosphates (NDPs) to deoxynucleoside diphosphates (dNDPs). This RNR is composed of two homodimeric subunits: R1 and R2. R1 binds the NDPs in the active site, and R2 harbors the essential di-iron tyrosyl radical (Y*) cofactor. In this paper, we used PELDOR, a method that detects weak electron-electron dipolar coupling, to make the first direct measurement of the distance between the two Y*'s on each monomer of R2. In the crystal structure of R2, the Y*'s are reduced to tyrosines, and consequently R2 is inactive. In R2, where the Y*'s assume a well-defined geometry with respect to the protein backbone, the PELDOR method allows measurement of a distance of 33.1 +/- 0.2 A that compares favorably to the distance (32.4 A) between the center of mass of the spin density distribution of each Y* on each R2 monomer from the structure. The experiments provide the first direct experimental evidence for two Y*'s in a single R2 in solution.