SOLUTION STRUCT STUDIES OF NITROGENASE PROTEINS BY SMALL ANGLE XRAY SCATTERING

MoFe蛋白中的FeMo辅因子被认为是 基质（例如大气N2）结合和还原位点 固氮酶系统 FeMo簇，通过不同的 制备方法，是FeMo辅因子的子集。 群集 表现出非常相似的S=3/2 EPR信号，并抑制插入 将辅因子重新注入到缺乏辅因子的MoFe蛋白中。 然而，簇合物不含高柠檬酸盐，并且少了一个Fe 原子在第一配位壳层，并有一个变化的长 范围命令。 该簇不能激活铁钼辅因子缺陷型 MoFe蛋白的形式。 之前的SAXS研究表明， 余因子解不是均匀的;余因子存在于大的 聚集体（Rg中最多25个E）以及小的寡聚体形式， 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。

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.