Mechanistic Investigation of a Non-Heme Iron Enzyme Catalyzed Epoxidation in (-)-4′-Methoxycyclopenin Biosynthesis
Mechanistic Investigation of a Non-Heme Iron Enzyme Catalyzed Epoxidation in (-)-4′-Methoxycyclopenin Biosynthesis
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DOI：
10.1021/jacs.6b05400
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发表时间：
2016-08-24
影响因子：
15
通讯作者：
Guo, Yisong
中科院分区：
文献类型：
--
作者：
Chang, Wei-chen;Li, Jikun;Guo, Yisong
已经提出了α-KG依赖性非血红素铁酶催化氧原子插入各种天然产物中的烯属部分的机制，但尚未详细研究。使用包括瞬态动力学、穆斯堡尔谱和质谱的方法的组合，我们证明AsqJ催化的（-）-4 '-甲氧基环戊二烯形成使用高自旋Fe（IV）-氧代中间体进行环氧化。此外，使用天然底物4 '-甲氧基脱氢环肽素和机械探针脱氢环肽素对来自反应的O-16/O-18同位素掺入的产物分析揭示了支持非血红素铁酶催化中Fe（IV）-氧代物种的氧代羟基互变异构的证据。
Mechanisms have been proposed for alpha-KG dependent non-heme iron enzyme catalyzed oxygen atom insertion into an olefinic moiety in various natural products, but they have not been examined in detail. Using a combination of methods including transient kinetics, Mossbauer spectroscopy, and mass spectrometry, we demonstrate that AsqJ-catalyzed (-)-4'-methoxycyclopenin formation uses a high-spin Fe(IV)-oxo intermediate to carry out epoxidation. Furthermore, product analysis on O-16/O-18 isotope incorporation from the reactions using the native substrate, 4'-methoxydehydrocyclopeptin, and a mechanistic probe, dehydrocyclopeptin, reveals evidence supporting oxo hydroxo tautomerism of the Fe(IV)-oxo species in the non-heme iron enzyme catalysis.