Insights into the Desaturation of Cyclopeptin and its C3 Epimer Catalyzed by a non-Heme Iron Enzyme: Structural Characterization and Mechanism Elucidation.
Hsuan-Jen LiaoJikun LiJhih-Liang HuangMadison DavidsonIgor KurnikovTe-Sheng LinJustin L LeeMaria KurnikovaYisong GuoNei-Li ChanWei-Chen ChangPublished in: Angewandte Chemie (International ed. in English) (2018)
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.