摘要
By incubating the reduced MoFe protein from Azotobacter vinelandii with O phenanthroline under air and chromatographying the incubated solution on Sephadex G 25 column, inactive MoFe protein could be obtained. Its acetylene reduction activity was remarkably recovered not only by incubation with the reconstituent solution composed of KMnO 4,ferric homocitrate, Na 2S and dithiothreitol,Azotobacter vinelandii with O phenanthroline under air and chromatographying the incubated solution on Sephadex G 25 column, inactive MoFe protein could be obtained. Its acetylene reduction activity was remarkably recovered not only by incubation with the reconstituent solution composed of KMnO 4,ferric homocitrate, Na 2S and dithiothreitol, with O phenanthroline under air and chromatographying the incubated solution on Sephadex G 25 column, inactive MoFe protein could be obtained. Its acetylene reduction activity was remarkably recovered not only by incubation with the reconstituent solution composed of KMnO 4,ferric homocitrate, Na 2S and dithiothreitol, but also with a mixture of 4Fe∶4S clusters and another cluster which had two structure units of 1Mo∶3Fe∶4S bridged by three -OCH 3- at the Mo atoms. Neither the reconstituent solution nor the mixture could reactivate apo MoFe proteins from the mutants deleting nifE and nifH genes and from the mutant UW 45 , which could be reactivated by the FeMoco extracted from the MoFe protein. The results indicated that the FeMoco deficient MoFe proteins from these mutants seemed to be reconstituted only by the clusters which were probably structures only similar to FeMoco. The partially metallocluster deficient MoFe protein could be reconstituted by the clusters with a certain kind of structure and composition; and was changed into different nitrogenase proteins with the ability to fix nitrogen.
棕色固氮菌（Ａｚｏｔｏｂａｃｔｅｒ ｖｉｎｅｌａｎｄｉｉ）钼铁蛋白与邻菲口罗啉和Ｏ２ 保温并经凝胶柱层析后，成为部分缺失Ｐ－ｃｌｕｓｔｅｒ和ＦｅＭｏｃｏ 的失活蛋白。由３ 个－ ＯＣＨ３－ 连结于Ｍｏ原子间的２ 个１Ｍｏ∶３Ｆｅ∶４Ｓ结构单位组成的原子簇与４Ｆｅ∶４Ｓ原子簇的混合液，以及由ＫＭｎＯ４、高柠檬酸铁、Ｎａ２Ｓ和二硫苏糖醇组成的重组液均可使这种失活蛋白明显恢复Ｃ２Ｈ２ 还原活性，但都不能使可被ＦｅＭｏｃｏ 激活的ｎｉｆＥ和ｎｉｆＨ 基因缺失突变种及ＵＷ ４５的Ａｐｏ－ＭｏＦｅ 蛋白得到激活。表明，不能合成ＦｅＭｏｃｏ 的固氮菌突变种蛋白只能与具有ＦｅＭｏｃｏ相似或基本相似结构的原子簇进行体外重组，而部分缺失金属原子簇的钼铁蛋白能与具有一定结构和组成的原子簇进行体外重组，变为具有催化氮还原能力的各种固氮酶组分蛋白。
