Huang Jhih-Liang, Tang Yijie, Yu Cheng-Ping, Sanyal Dev, Jia Xinglin, Liu Xinyu, Guo Yisong, Chang Wei-Chen
Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States.
Department of Chemistry , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States.
Biochemistry. 2018 Mar 27;57(12):1838-1841. doi: 10.1021/acs.biochem.8b00115. Epub 2018 Mar 13.
Two non-heme iron enzymes, IsnB and AmbI3, catalyze a novel decarboxylation-assisted olefination to produce indole vinyl isonitrile, an important building block for many natural products. Compared to other reactions catalyzed by this enzyme family, decarboxylation-assisted olefination represents an attractive biosynthetic route and a mechanistically unexplored pathway in constructing a C═C bond. Using mechanistic probes, transient state kinetics, reactive intermediate trapping, spectroscopic characterizations, and product analysis, we propose that both IsnB and AmbI3 initiate stereoselective olefination via a benzylic C-H bond activation by an Fe(IV)-oxo intermediate, and the reaction likely proceeds through a radical- or carbocation-induced decarboxylation to complete C═C bond installation.
两种非血红素铁酶IsnB和AmbI3催化一种新型的脱羧辅助烯化反应，生成吲哚乙烯基异腈，这是许多天然产物的重要组成部分。与该酶家族催化的其他反应相比，脱羧辅助烯化反应是一种具有吸引力的生物合成途径，也是构建碳碳双键时一种尚未被探索的机制途径。通过机理探针、瞬态动力学、反应中间体捕获、光谱表征和产物分析，我们提出IsnB和AmbI3均通过Fe(IV)-氧代中间体引发苄基碳氢键活化，从而启动立体选择性烯化反应，并且该反应可能通过自由基或碳正离子诱导的脱羧反应来完成碳碳双键的构建。
