Theoretical study on the inhibition mechanisms of heavy metal ions on urease activity.
Theoretical study on the inhibition mechanisms of heavy metal ions on urease activity.
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DOI：
10.1016/j.chemosphere.2023.140416
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发表时间：
2023-10
期刊：
影响因子：
8.8
通讯作者：
Mei-Chiung Huang;P. Cui;Jing Zhou;Cun Liu;Yujun Wang
中科院分区：
文献类型：
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作者：
Mei-Chiung Huang;P. Cui;Jing Zhou;Cun Liu;Yujun Wang
土壤脲酶对土壤重金属污染高度敏感，可作为土壤健康的生物指示剂。然而，重金属对脲酶的抑制机理却知之甚少。双金属取代的影响（即，Cd、Co、Cu、Hg和Zn）对尿素在脲酶中的结合及其随后的分解的影响。双金属取代改变了双金属配合物的结构特征以及双金属与配位尿素分子的羰基-O之间的M−O键长，削弱了双金属配合物中尿素的结合能，从而进一步影响了尿素的转化。在通过分子内质子转移的尿素分解中，由于配合物中尿素的弱结合和尿素分子内的氢键作用，所有双金属配合物都具有高活化势垒，因此难以自发发生。在水辅助分子间质子转移尿素分解反应中，水分子的加入降低了尿素分解反应的能垒。无论尿素的分解途径如何，双金属取代都改变了中间体和过渡态的M−O键长和氢键模式，并且还通过调节分解的尿素分子内的C-N键长来影响所产生的NH3从双金属配合物中的离开。总体而言，理论研究提供了深入了解的分子机制，重金属对脲酶活性的抑制作用。
Soil urease is highly sensitive to soil heavy metal pollution, and thus its activity can be used as bio-indicator of soil health. However, little is known about the inhibition mechanisms of heavy metals on urease. The effects of dimetallic substitution (i.e., Cd, Co, Cu, Hg, and Zn) on the binding of urea in the urease and its subsequent decomposition were studied using quantum chemical methodologies with a urease mimic (phthalazine-dinickel complex). The dimetallic substitution altered the structural features of the dimetal complexes and the M−O bond length between the dimetals and the carbonyl-O of coordinated urea molecules, weakening the binding energies of urea in dimetal complexes, which further affected the transformation of urea. In the urea decomposition via intra-molecular proton transfer, all dimetal complexes have a high activation barrier due to the weak binding of urea in complexes and hydrogen bonding within urea molecules, which are therefore difficult to occur spontaneously. In the urea decomposition via water-assisted inter-molecular proton transfer, the addition of water molecules decreased the energy barrier of urea decomposition. Regardless of the urea decomposition pathway, the dimetallic substitution altered the M−O bond length and hydrogen bond pattern of intermediates and transition states, and also affected the leave of the resulting NH3from the dimetal complexes by regulating the C–N bond length within the decomposed urea molecule. Overall, the theoretical study provided insight into the molecular mechanisms of the inhibitory effects of heavy metals on urease activity.