Nitrogenase MoFe-protein at 1.16 Ã… resolution:: A central ligand in the FeMo-cofactor
Nitrogenase MoFe-protein at 1.16 Ã… resolution:: A central ligand in the FeMo-cofactor
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DOI：
10.1126/science.1073877
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发表时间：
2002-09-06
期刊：
影响因子：
56.9
通讯作者：
Rees, DC
中科院分区：
文献类型：
--
作者：
Einsle, O;Tezcan, FA;Rees, DC
固氮酶钼铁蛋白的高分辨率晶体学分析揭示了一个以前未被识别的配体协调的催化必需的铁钼辅因子的中心的六个铁原子。该配体的电子密度在分辨率低于1.55埃的结构中被掩蔽，这是由于辅因子中周围铁和硫原子的傅立叶级数终止波纹。中心原子完成六个铁原子的近似四面体配位，而不是基于较低分辨率结构提出的三角配位。在1.16埃分辨率下的晶体学细化与这个新检测到的成分是轻元素，最可能是氮一致。辅因子中氮原子的存在对固氮酶还原二氮的机制具有重要意义。
A high-resolution crystallographic analysis of the nitrogenase MoFe-protein reveals a previously unrecognized ligand coordinated to six iron atoms in the center of the catalytically essential FeMo-cofactor. The electron density for this ligand is masked in structures with resolutions lower than 1.55 angstroms, owing to Fourier series termination ripples from the surrounding iron and sulfur atoms in the cofactor. The central atom completes an approximate tetrahedral coordination for the six iron atoms, instead of the trigonal coordination proposed on the basis of lower resolution structures. The crystallographic refinement at 1.16 angstrom resolution is consistent with this newly detected component being a light element, most plausibly nitrogen. The presence of a nitrogen atom in the cofactor would have important implications for the mechanism of dinitrogen reduction by nitrogenase.