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首页> 外文期刊>Biochemistry >Diazene (HN=NH) Is a Substrate for Nitrogenase:Insights into the Pathway of N2 Reduction
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Diazene (HN=NH) Is a Substrate for Nitrogenase:Insights into the Pathway of N2 Reduction

机译：重氮（HN = NH）是用于氮酶的底物：N2减少途径的见解

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摘要

Nitrogenase catalyzes the sequential addition of six electrons and six protons to a N2 that is bound to the active site metal cluster FeMo-cofactor,yielding two ammonia molecules.The nature of the intermediates bound to FeMo-cofactor along this reduction pathway remains unknown,although it has been suggested that there are intermediates at the level of reduction of diazene (HN=NH,also called diimide) and hydrazine (H2N-NH2).Through in situ generation of diazene during nitrogenase turnover,we show that diazene is a substrate for the wild-type nitrogenase and is reduced to NH3.Diazene reduction,like N2 reduction,is inhibited by H2.This contrasts with the absence of H2 inhibition when nitrogenase reduces hydrazine.These results support the existence of an intermediate early in the N2 reduction pathway at the level of reduction of diazene.Freeze-quenching a MoFe protein variant with alpha-195~(His) substituted by Gln and alpha-70~(Val) substituted by Ala during steady-state turnover with diazene resulted in conversion of the S = 3/2 resting state FeMo-cofactor to a novel .5 = V2 state with g1 = 2.09,g2 = 2.01,and g3 ~ 1.98.15N- and 1H-ENDOR establish that this state consists of a diazene-derived [-NH_x] moiety bound to FeMo-cofactor.This moiety is indistinguishable from the hydrazine-derived [-NH_x] moiety bound to FeMo-cofactor when the same MoFe protein is trapped during turnover with hydrazine.These observations suggest that diazene joins the normal N2-reduction pathway,and that the diazene- and hydrazine-trapped turnover states represent the same intermediate in the normal reduction of N2 by nitrogenase.Implications of these findings for the mechanism of N2 reduction by nitrogenase are discussed.
机译：氮酰基催化六个电子和六个质子的连续添加到与活性位点金属聚类股骨辅因子结合的N 2，产生两个氨分子。沿着这种减少途径沿着股票辅助因子结合的中间体的性质仍然未知，虽然已经提示，在氮酶转运期间，氮氮化氮烯（HN = NH，也称为二酰亚胺）和肼（H2N-NH2）的中间体中间体的中间体在氮酶周转期间，含有氢氮化氮原位的含量。野生型氮酶并降低至NH3.DIOZENE减少，如N2还原，通过H2抑制。当氮酶减少肼时，没有H2抑制对比。这些结果支持在N2还原途径早期存在中间体在重氮的还原水平。用由Ala取代的α-195〜（他）用α-195〜（他）用D稳态转换而取代的α-195〜（HIS）。 IAZENE导致S = 3/2休息状态股骨COFOCTOR转换为G1 = 2.09，G2 = 2.01，G3〜1.98.15n-and 1h-negor建立了这个国家的新的.5 = V2状态。与股骨辅因子结合的重环氮衍生的[-NH_X]部分。当与肼替纳西的倒装时捕获相同的MOFE蛋白时，该部分与股骨辅因子结合的肼衍生的[-NH_X]部分难以区分。这是观察重氮管加入正常的N 2还原途径，并将重氮衍生的截转周转状态表示在N 2的正常降低中相同的中间体。讨论了这些结果的这些发现，用于通过氮酶进行N2还原的机制。

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  • 来源
    《Biochemistry》 |2007年第23期|共11页
  • 作者

    Brett M.Barney; Jammi McClead; Dmitriy Lukoyanov;

  • 作者单位

    Department of Chemistry and Biochemistry Utah State University Logan Utah 84322 Department of Biochemistry Virginia Tech Blacksburg Virginia 24061 and Department of Chemistry Northwestern University Evanston Illinois 60208;

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  • 正文语种 eng
  • 中图分类 生物化学;
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