THE NITROGENASE FEMO-COFACTOR AND P-CLUSTER PAIR - 2.2-ANGSTROM RESOLUTION STRUCTURES
THE NITROGENASE FEMO-COFACTOR AND P-CLUSTER PAIR - 2.2-ANGSTROM RESOLUTION STRUCTURES
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DOI：
10.1126/science.8484118
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发表时间：
1993-05-07
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：
CHAN, MK;KIM, JS;REES, DC
最近提出的固氮酶固氮铁（MoFe）-蛋白质的FeMo-辅因子和P-簇对的结构已在2.2埃分辨率下得到晶体学验证。值得注意的是，在两种类型的金属中心中均未观察到六配位硫原子。因此，在铁钼辅因子中的六个桥接铁原子通过非蛋白质配体进行三角配位，尽管可能存在一些铁-铁键合相互作用，可以为这些位点提供第四配位相互作用。P-簇对中的两个簇硫非常接近（约2.1埃），表明它们形成二硫键。这些研究结果表明，一个空腔存在于内部的FeMo-辅因子，可能参与底物结合，并表明在P-集群对的氧化还原反应可能与二硫化物和硫化物氧化态之间的两个集群结合硫的过渡。
Structures recently proposed for the FeMo-cofactor and P-cluster pair of the nitrogenase molybdenum-iron (MoFe)-protein from Azotobacter vinelandii have been crystallographically verified at 2.2 angstrom resolution. Significantly, no hexacoordinate sulfur atoms are observed in either type of metal center. Consequently, the six bridged iron atoms in the FeMo-cofactor are trigonally coordinated by nonprotein ligands, although there may be some iron-iron bonding interactions that could provide a fourth coordination interaction for these sites. Two of the cluster sulfurs in the P-cluster pair are very close together (approximately 2.1 angstroms), indicating that they form a disulfide bond. These findings indicate that a cavity exists in the interior of the FeMo-cofactor that could be involved in substrate binding and suggest that redox reactions at the P-cluster pair may be linked to transitions of two cluster-bound sulfurs between disulfide and sulfide oxidation states.