SOLUTION STRUCT STUDIES OF NITROGENASE PROTEINS BY SMALL ANGLE XRAY SCATTERING

MoFe蛋白中的FEMO辅助因子被认为是 底物(如大气中的氮)结合和还原位置 固氮酶系统。FEMO簇，由不同的 制备方法，是FeMo辅因子的一个子集。集群 表现出非常类似的S=3/2EPR信号，并抑制插入 将辅因子重新转化为辅因子缺陷的MoFe蛋白。 然而，该簇不包含高柠檬酸，并且少了一个铁 原子在第一配位壳层中，并在长的 范围顺序。该群集无法激活缺乏FEMO辅因子 MoFe蛋白的一种形式。之前的一项SAXS研究表明，FEMO 辅因子解决方案不是均匀的；辅因子大量存在 聚集体(在Rg中高达25E)以及具有以下特性的小寡聚形式 平均RG为6.96 E。我们有兴趣比较 簇的聚集状态与辅因子的聚集状态 解决小角x射线散射问题。

The FeMo cofactor in the MoFe protein is believed to be the substrate (e.g. atmospheric N2) binding and reducing site in the nitrogenase system. The FeMo cluster, obtained by a different preparation method, is a subset of the FeMo cofactor. The cluster exhibits a very similar S=3/2 EPR signal, and inhibits the insertion of the cofactor back into the cofactor-deficient MoFe protein. However, the cluster does not contain homocitrate, and has one less Fe atom in the first coordination shell and has a change in the long range order. The cluster cannot activate the FeMo-cofactor-deficient form of the MoFe protein. A previous SAXS study shows that the FeMo cofactor solution is not homogenous; the cofactor exists in large aggregates (upto 25 E in Rg) as well as in small oligomeric forms with an average Rg of 6.96 E. We are interested in comparing the aggregation state of the cluster with that of the cofactor by using solution small-angle x-ray scattering.