Modeling the Catalytic Cycle of Glutathione Peroxidase by Nuclear Magnetic Resonance Spectroscopic Analysis of Selenocysteine Selenenic Acids
Modeling the Catalytic Cycle of Glutathione Peroxidase by Nuclear Magnetic Resonance Spectroscopic Analysis of Selenocysteine Selenenic Acids
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DOI：
10.1021/jacs.1c02383
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发表时间：
2021-04-22
影响因子：
15
通讯作者：
Goto, Kei
中科院分区：
文献类型：
--
作者：
Masuda, Ryosuke;Kimura, Ryutaro;Goto, Kei
尽管硒代半胱氨酸硒酸 (Sec-SeOHs) 已被认为是谷胱甘肽过氧化物酶 (GPx) 催化循环中的关键中间体，但迄今为止，在蛋白质或小分子系统中直接观察 Sec-SeOH 的例子仍然难以捉摸，主要是由于其不稳定性。在这里，我们首次报告了在具有摇篮型保护基团的小分子硒代半胱氨酸和硒肽模型系统中形成 Sec-SeOH 的直接光谱（H-1 和 Se-77 NMR）证据。使用 NMR 可观察的 Sec-SeOH 模型研究了 GPx 的催化循环。迄今为止提出的所有化学过程，即不仅是经典催化循环的化学过程，而且还涉及旁路机制的化学过程，包括 Sec-SeOH 分子内环化为相应的五元环硒基酰胺，均以逐步的方式进行了研究。
Although selenocysteine selenenic acids (Sec-SeOHs) have been recognized as key intermediates in the catalytic cycle of glutathione peroxidase (GPx), examples of the direct observation of Sec-SeOH in either protein or small-molecule systems have remained elusive so far, mostly due to their instability. Here, we report the first direct spectroscopic (H-1 and Se-77 NMR) evidence for the formation of Sec-SeOH in small-molecule selenocysteine and selenopeptide model systems with a cradle-type protective group. The catalytic cycle of GPx was investigated using NMR-observable Sec-SeOH models. All the hitherto proposed chemical processes, i.e., not only those of the canonical catalytic cycle but also those involved in the bypass mechanism, including the intramolecular cyclization of Sec-SeOH to the corresponding five-membered ring selenenyl amide, were examined in a stepwise manner.