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Insights into the Desaturation of Cyclopeptin and its C3 Epimer Catalyzed by a non‐Heme Iron Enzyme: Structural Characterization and Mechanism Elucidation |
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| Authors: | Hsuan‐Jen Liao Jikun Li Jhih‐Liang Huang Madison Davidson Igor Kurnikov Te‐Sheng Lin Justin L Lee Prof Maria Kurnikova Prof Yisong Guo Prof Nei‐Li Chan Prof Wei‐chen Chang |
| Institution: | 1. Institute of Biochemistry and Molecular Biology, College of Medicine, National (Taiwan) University, Taipei, Taiwan;2. Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA;3. Department of Chemistry, North Carolina State University, Raleigh, NC, USA |
| Abstract: | AsqJ, an iron(II)‐ and 2‐oxoglutarate‐dependent enzyme found in viridicatin‐type alkaloid biosynthetic pathways, catalyzes sequential desaturation and epoxidation to produce cyclopenins. Crystal structures of AsqJ bound to cyclopeptin and its C3 epimer are reported. Meanwhile, a detailed mechanistic study was carried out to decipher the desaturation mechanism. These findings suggest that a pathway involving hydrogen atom abstraction at the C10 position of the substrate by a short‐lived FeIV‐oxo species and the subsequent formation of a carbocation or a hydroxylated intermediate is preferred during AsqJ‐catalyzed desaturation. |
| Keywords: | carbocations C− C bond formation desaturation enzyme mechanisms viridicatin |