Proton transfer to synthetic Fe-S-based clusters
Proton transfer to synthetic Fe-S-based clusters
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DOI：
10.1016/j.ccr.2004.12.021
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发表时间：
2005-09-01
影响因子：
20.6
通讯作者：
Henderson, RA
中科院分区：
文献类型：
--
作者：
Henderson, RA
描述了含有立方体{Fe_4S_4}或{MoFe_3S_4}核的合成Fe-S基团簇的质子化化学，重点讨论了与团簇结合的质子数目、质子结合的位置、质子化团簇的pK(A)‘S、质子转移速率以及团簇的金属组成对所有这些因素的影响。对合成的Fe-S基团簇的研究结果揭示了一般的反应模式，预计这种模式也将在天然的Fe-S基团簇中运行。特别是，我们考虑了固氮酶活性部位的作用，以及活性部位的金属组成如何调节酶的反应活性。三种主要固氮酶(钼固氮酶、V固氮酶和纯铁固氮酶)的相对效率已经通过考虑合成簇合物的结合亲和力和质子化反应活性而合理化。结果表明，与V-辅因子和纯Fe-辅因子相比，辅因子中Mo的存在导致与氮素的结合亲和力较高，质子转移速率较慢，从而导致产生氢气的速率较慢。推测辅因子中的钼通过抑制活性中心的氢酶行为来促进固氮。(C)2005 Elsevier B.V.保留所有权利。
The protonation chemistry of synthetic Fe-S-based clusters containing cuboidal {Fe4S4} or {MoFe3S4} cores is described with an emphasis on: the number of protons that bind to the clusters; where the protons bind; the pK(a)'s of the protonated clusters; the rates of proton transfer and how the metal composition of the cluster influences all these factors. The results from the studies on the synthetic Fe-S-based clusters reveal general reactivity patterns, which it is anticipated, would also be operating, in natural Fe-S-based clusters. In particular, we consider the action of the active sites of the nitrogenases, and how the metal composition of the active site may modulate the reactivity of the enzyme. The relative efficiencies of the three principal nitrogenases (Mo-nitrogenase, V-nitrogenase and Fe-only-nitrogenase) have been rationalised by consideration of the binding affinities and protonation reactivities of synthetic clusters. It is proposed that the presence of Mo in cofactor leads to higher binding affinity for dinitrogen and a slower rate of proton transfer, and hence slower rate of dihydrogen production than the V-cofactor or Fe-only-cofactor. It is proposed that Mo in cofactor facilitates nitrogen fixation by suppressing the hydrogenase behaviour of the active site. (c) 2005 Elsevier B.V. All rights reserved.