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首页> 外文期刊>Biochemistry >ISOLATION OF TWO FORMS OF THE NITROGENASE VFE PROTEIN FROM AZOTOBACTER VINELANDII
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ISOLATION OF TWO FORMS OF THE NITROGENASE VFE PROTEIN FROM AZOTOBACTER VINELANDII

机译：酿酒酵母中两种形式的固氮酶VFE蛋白的分离

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When Q-Sepharose was used in the purification of the V nitrogenase proteins from Azotobacter vinelandii, an increase in resolution was observed that resulted in a separation of the nitrogenase component 1 protein (Av1') into two forms, labeled Avl'(A) and Av1'(B). Even though both forms possessed the same enzymatic behavior, Av1'(A) exhibited a lower specific activity and migrated during gel filtration with an apparent lower molecular weight than Av1'(B). Furthermore, SDS-polyacrylamide gel, electrophoresis showed different relative compositions of the two major subunits of both forms, with Av1'(A) possessing a trimer (alpha beta(2)) pattern compared to the more typical tetramer (alpha(2) beta(2)) pattern found for Av1'(B). Metal analysis indicated a V-to-Fe ratio of 1:19 for Av1'(A) and 1:15 (or 2:30) for Av1'(B), while acid-labile sulfide analysis showed that Av1'(A) possessed about half as much sulfide as Av1'(B). EPR spectroscopy revealed that both proteins retained the S = 3/2 and S = 1/2 signals observed in earlier isolations, with an additional S = 1/2 signal present in the spectrum of protein A. These results suggest that Av1'(A) is an incomplete form of the VFe protein, containing only one cofactor and one P duster with an additional [Fe-4-S-4]-like cluster. The presence of a V storage protein in A. vinelandii was also investigated. Although no V storage protein was found, two V-binding proteins were observed.
机译：当Q-琼脂糖用于从葡萄固氮菌中纯化V固氮酶蛋白时，观察到分离度的增加，导致固氮酶组分1蛋白（Av1'）分离为两种形式，分别标记为Avl'（A）和Av1'（B）。即使两种形式都具有相同的酶促行为，Av1'（A）仍显示出较低的比活性，并且在凝胶过滤过程中以明显低于Av1'（B）的分子量迁移。此外，SDS-聚丙烯酰胺凝胶电泳显示两种形式的两个主要亚基的相对相对组成不同，与更典型的四聚体（alpha（2）β相比，Av1'（A）具有三聚体（alpha beta（2））模式（2））为Av1'（B）找到的模式。金属分析表明，Av1'（A）的钒铁比为1：19，Av1'（B）的钒铁比为1:15（或2:30），而酸不稳定的硫化物分析表明，Av1'（A）硫化物的含量是Av1'（B）的一半。 EPR光谱显示，这两种蛋白质均保留了早期分离物中观察到的S = 3/2和S = 1/2信号，并且在蛋白质A的光谱中还存在另外的S = 1/2信号。这些结果表明，Av1'（A ）是VFe蛋白的不完整形式，仅包含一个辅因子和一个P喷粉，以及一个额外的[Fe-4-S-4]-样簇。还研究了A. vinelandii中V贮藏蛋白的存在。尽管未发现V贮藏蛋白，但观察到两个V结合蛋白。

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