催化学报 ›› 2022, Vol. 43 ›› Issue (4): 913-927.DOI: 10.1016/S1872-2067(21)63974-8

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对比生物体系以及合成体系中单核铜氧物种对碳氢键和氧氢键活化的理论研究展望

吴鹏, 张锦岩, 陈倩倩, 彭炜, 王斌举*()   

  1. 厦门大学化学化工学院, 固体表面物理化学国家重点实验室, 福建省理论与计算化学重点实验室, 福建厦门361005
  • 收稿日期:2021-09-24 接受日期:2021-09-24 出版日期:2022-03-05 发布日期:2021-12-28
  • 通讯作者: 王斌举
  • 作者简介:第一联系人:

    共同第一作者

  • 基金资助:
    基金来源: 国家重点研发计划(2019YFA0906400);国家自然科学基金(22122305);国家自然科学基金(22121001);国家自然科学基金(21933009)

Theoretical perspective on mononuclear copper-oxygen mediated C-H and O-H activations: A comparison between biological and synthetic systems

Peng Wu, Jinyan Zhang, Qianqian Chen, Wei Peng, Binju Wang*()   

  1. State Key Laboratory of Physical Chemistry of Solid Surface, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
  • Received:2021-09-24 Accepted:2021-09-24 Online:2022-03-05 Published:2021-12-28
  • Contact: Binju Wang
  • About author:Binju Wang obtained his PhD in 2012 from Xiamen University in China. After two periods of post-doctoral research at the Hebrew University of Jerusalem, Israel (with Prof. Sason Shaik) and Universitat de Barcelona, Spain (with Prof. Carme Rovira), he joined Xiamen University in 2018 as a full professor. His current research interest focuses on the use of multiscale modeling to decipher the catalytic mechanisms of metalloenzymes, including O2 and H2O2 activations, electronic state and spin-state reactivities, protein environment effects, as well as the rational design of metalloenzymes for biocatalysis. Professor Wang has published over 60 peer reviewed publications.
    First author contact:

    These authors contributed equally.

  • Supported by:
    National Key Research and Developement Program of China(2019YFA0906400);National Natural Science Foundation of China(22122305);National Natural Science Foundation of China(22121001);National Natural Science Foundation of China(21933009)

摘要:

由于具有较好的催化性能, 含过渡金属的酶一直备受研究者的关注. 其中, 铜作为生物体中含量仅次于铁和锌的过渡金属, 在新陈代谢过程中发挥着重要作用. 铜酶广泛存在于自然界中, 该类生物大分子涉及电子转移、氧化还原、氧气的运输与活化等生物化学过程. 多种铜酶在氧气活化方面表现出引人注目的性质, 例如: 颗粒状甲烷单加氧酶(pMMO)、多糖单加氧酶(LPMO)、双铜单加氧酶肽基甘氨酸α-羟基化酶(PHM)和多巴胺β-单加氧酶(DβM), 它们均可活化氧气, 并生成相应的铜-氧活性物种. 铜酶或铜配合物活化氧气可生成多种铜-氧活性物种, 包括Cu(II)-O2, Cu(II)-OOH(R), Cu(II)-O及Cu(III)-OH等. 这些活性物种通常具有不同强度的攫氢能力, 可能是铜酶C‒H/O‒H活化的活性氧物种. 近几十年来, 为了深入揭示铜酶的催化活性和反应机理, 阐明关键铜-氧中间体的结构和性质, 研究人员合成了众多含铜配合物体系, 并模拟探索了铜-氧活性物种的反应活性尤其是对底物C‒H/O‒H键活化能力.
本文聚焦于含有单铜活性位点的酶及其配合物体系. 结合密度泛函理论计算, 深入比较了铜酶及配合物体系中铜-氧活性物种反应活性, 总结得到以下普遍规律: (1)MN15泛函可准确描述单核铜氧配合物的热动力学性质, 对各类铜氧物种催化的C‒H/O‒H键活化计算中, 得到的热动力学性质都能与实验结果很好地吻合; (2)Cu(II)-O2在生物体系和人工合成体系中表现出一致的反应活性: 它对O‒H键活化表现出高反应活性, 但对C‒H键反应活性较差, 因此不太可能是铜酶中C‒H活化的活性中间体; (3)Cu(II)-OOH没有活化C‒H键的能力, 但其近端氧原子上的自由基特性使其能够攫取中等强度O‒H键上的氢原子, 另外该物种还可以与另一分子Cu(I)偶联形成双铜物种. 因此, 在生物体系和合成体系中Cu(II)-OOH均可作为氧气活化路径上的关键中间体, 但并不能作为C‒H键活化的氧化剂; (4)Cu(II)-O对C‒H键活化具有高反应活性, 因此该类物种可能在单铜单加氧酶的C‒H键活化中起关键作用; (5)尽管许多实验证明Cu(III)-OH对C‒H键的活化有较高的反应活性, 但是在单加氧酶中, 生成这一物种在热力学上是非常不利的, 因此不太可能是单加氧酶中的活性物种. 综上, 本文的观点可以为生物体系及合成体系中的铜氧物种的反应活性提供新的视角与思考.

关键词: 氧气活化, 铜(II)超氧, 铜(II)氢过氧, 铜(II)氧自由基, 铜(III)氢氧化物, 碳氢键活化, 氧气活化多糖裂解单加氧酶, 颗粒甲烷单加氧酶

Abstract:

Dioxygen activations constitute one of core issues in copper-dependent metalloenzymes. Upon O2 activation, copper-dependent metalloenzymes such as particulate methane monooxygenases (pMMOs), lytic polysaccharide monooxygenases (LPMOs) and binuclear copper enzymes PHM and DβM, are able to perform various challenging C-H bond activations. Meanwhile, various copper-oxygen core containing complexes have been synthetized to mimic the active species of metalloenzymes. Dioxygen activation by mononuclear copper active site may generate various copper-oxygen intermediates, including Cu(II)-superoxo, Cu(II)-hydroperoxo, Cu(II)-oxyl as well as the Cu(III)-hydroxide species. Intriguingly, all these species have been invoked as the potential active intermediates for C-H/O-H activations in either biological or synthetic systems. Due to the poor understanding on reactivities of copper-oxygen complex, the nature of active species in both biological and synthetic systems are highly controversial. In this account, we will compare the reactivities of various mononuclear copper-oxygen species between biological systems and the synthetic systems. The present study is expected to provide the consistent understanding on reactivities of various copper-oxygen active species in both biological and synthetic systems.

Key words: Dioxygen activation, Cu(II)-superoxo, Cu(II)-hydroperoxo, Cu(II)-oxyl, Cu(III)-hydroxide, C-H activation, Lytic polysaccharide monooxygenase, Particulate methane monooxygenase