<br>铁血红素/亚铁血红素作为电子载体直接参与厌氧氨氧化过程中肼的合成和分解,Environmental Science & Technology

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铁血红素/亚铁血红素作为电子载体直接参与厌氧氨氧化过程中肼的合成和分解
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2024-05-23 , DOI: 10.1021/acs.est.3c08525
Zhenxin Wang ₁ , Qilin Yu ₁ , Zhiqiang Zhao ₁ , Yaobin Zhang ₁

Affiliation

厌氧氨氧化菌将NH ₄ ⁺与NO在肼合酶的作用下反应生成N ₂ H ₄ ，再在肼脱氢酶的作用下将N ₂ H ₄分解生成N ₂ 。铁血红素/铁血红素作为肼合酶和肼脱氢酶的活性中心，由于其高氧化还原活性，被认为在厌氧氨氧化过程中N ₂ H ₄的合成和分解中发挥着至关重要的作用。然而，这一点尚未得到证实，并且铁血红素/铁血红素参与厌氧氨氧化过程的确切机制仍不清楚。本研究通过非生物和生物测定证实，亚铁血红素参与NH ₄ ⁺和NO反应生成N ₂ H ₄和亚铁血红素，产生的N ₂ H ₄与亚铁血红素反应生成N ₂和亚铁血红素。换句话说，亚铁血红素/亚铁血红素循环驱动NH ₄ ⁺和NO之间的连续反应。拉曼光谱、紫外可见光谱和X射线吸收精细结构光谱证实，亚铁血红素/亚铁血红素通过核心Fe ^II /Fe ^III循环参与N ₂ H ₄的合成和分解。通过密度泛函理论计算提出了亚铁血红素/亚铁血红素参与N ₂ H ₄合成和分解的机制。这些发现首次揭示了血红素电子转移机制，对于加深对Anammox的认识具有重要意义。

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Ferroheme/Ferriheme Directly Involved in the Synthesis and Decomposition of Hydrazine as an Electron Carrier during Anammox

Anammox bacteria performed the reaction of NH₄⁺ and NO with hydrazine synthase to produce N₂H₄, followed by the decomposition of N₂H₄ with hydrazine dehydrogenase to generate N₂. Ferroheme/ferriheme, which serves as the active center of both hydrazine synthase and hydrazine dehydrogenase, is thought to play a crucial role in the synthesis and decomposition of N₂H₄ during Anammox due to its high redox activity. However, this has yet to be proven and the exact mechanisms by which ferroheme/ferriheme is involved in the Anammox process remain unclear. In this study, abiotic and biological assays confirmed that ferroheme participated in NH₄⁺ and NO reactions to generate N₂H₄ and ferriheme, and the produced N₂H₄ reacted with ferriheme to generate N₂ and ferroheme. In other words, the ferroheme/ferriheme cycle drove the continuous reaction between NH₄⁺ and NO. Raman, ultraviolet–visible spectroscopy, and X-ray absorption fine structure spectroscopy confirmed that ferroheme/ferriheme is involved in the synthesis and decomposition of N₂H₄ via the core Fe^II/Fe^III cycle. The mechanism of ferroheme/ferriheme participation in the synthesis and decomposition of N₂H₄ was proposed by density functional theory calculations. These findings revealed for the first time the heme electron transfer mechanisms, which are of great significance for deepening the understanding of Anammox.

更新日期：2024-05-23

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