Visualizing the protons in a metalloenzyme electron proton transfer pathway
Visualizing the protons in a metalloenzyme electron proton transfer pathway
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DOI：
10.1073/pnas.1918936117
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发表时间：
2020-03-24
影响因子：
11.1
通讯作者：
Raven, Emma L.
中科院分区：
文献类型：
--
作者：
Kwon, Hanna;Basran, Jaswir;Raven, Emma L.
在氧化还原金属酶中，电子转移过程通常涉及质子的协同运动。这些过程被称为质子耦合电子转移，它们支持各种各样的生物过程，包括呼吸，能量转换，光合作用和金属酶催化。质子传递的机制是不完全理解的，部分原因是缺乏信息的确切质子位置和氢键结构在一个真正的金属酶质子途径。在这里，我们提出了一个2.1-A的中子晶体结构的氧化还原金属酶（抗坏血酸过氧化物酶）和它的还原底物（抗坏血酸）之间形成的复合物。在复合物的中子结构中，直接观察到电子/质子供体（抗坏血酸盐）和电子/质子转移途径中所涉及的所有残基的质子化状态。这些信息揭示了血红素催化氧活化过程中可能的质子运动，以及抗坏血酸氧化。
In redox metalloenzymes, the process of electron transfer often involves the concerted movement of a proton. These processes are referred to as proton-coupled electron transfer, and they underpin a wide variety of biological processes, including respiration, energy conversion, photosynthesis, and metalloenzyme catalysis. The mechanisms of proton delivery are incompletely understood, in part due to an absence of information on exact proton locations and hydrogen bonding structures in a bona fide metalloenzyme proton pathway. Here, we present a 2.1-A neutron crystal structure of the complex formed between a redox metalloenzyme (ascorbate peroxidase) and its reducing substrate (ascorbate). In the neutron structure of the complex, the protonation states of the electron/proton donor (ascorbate) and all of the residues involved in the electron/proton transfer pathway are directly observed. This information sheds light on possible proton movements during heme-catalyzed oxygen activation, as well as on ascorbate oxidation.