title: Mechanistic Investigation of a Non-Heme Iron Enzyme Catalyzed Epoxidation in (-)-4'-Methoxycyclopenin Biosynthesis.
abstract: Mechanisms have been proposed for α-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, Mössbauer 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 (16)O/(18)O 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.
authors.affiliation: Department of Chemistry, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Wei-Chen
authors.initials: WC
authors.lastname: Chang
authors.affiliation: Department of Chemistry, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States.
authors.forename: Jikun
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Chemistry, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States.
authors.forename: Justin L
authors.initials: JL
authors.lastname: Lee
authors.affiliation: Department of Environmental and Occupational Health, University of Pittsburgh , Pittsburgh, Pennsylvania 15219, United States.
authors.forename: Andrea A
authors.initials: AA
authors.lastname: Cronican
authors.affiliation: Department of Chemistry, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States.
authors.forename: Yisong
authors.initials: Y
authors.lastname: Guo
mesh_terms: D000475:Alkenes / Q000737:chemistry; D001233:Aspergillus nidulans / Q000201:enzymology; D001570:Benzodiazepinones / Q000737:chemistry / Q000378:metabolism; D055162:Biocatalysis; D004798:Enzymes / Q000378:metabolism*; D004852:Epoxy Compounds / Q000737:chemistry*; D007501:Iron; D007700:Kinetics; D010100:Oxygen / Q000737:chemistry
chemical_list: D000475:Alkenes; D001570:Benzodiazepinones; D004798:Enzymes; D004852:Epoxy Compounds; C007200:cyclopenin; D007501:Iron; D010100:Oxygen