title: Spectroscopic observation of iodosylarene metalloporphyrin adducts and manganese(V)-oxo porphyrin species in a cytochrome P450 analogue.
abstract: Different metalloporphyrin model compounds have been synthesized to study the mechanisms of cytochrome P450s with various terminal oxidants, and numerous intermediates have been reported. However, the detailed mechanism of the oxygen atom transfer from iodosylarene to the substrates remains unclear. Here we report the direct ultraviolet-visible spectroscopic observation of the soluble iodosylarene-manganese porphyrin adduct following catalytic oxidation using 2,4,6-tri-tert-butylphenol as the reductant. When the reductant is changed to cis-stilbene, the rate-determining step also changes. Both the iodosylarene-manganese porphyrin adduct and [(porphyrin)Mn(V)=O] species may be simultaneously observed. In the absence of reductant, the adduct of iodosylarene with sterically hindered [Mn(meso-tetrakis(2,6-dichlorophenyl)porphinato)Cl] is immediately formed, and smoothly converted into a high-valent [(porpyrinato)Mn=O]. Electrospray ionization mass spectrometry analysis of the reaction further confirms the transformation between these species. This study provides an insight into the mechanism of oxygen transfer within the haem-containing enzymatic systems.
authors.affiliation: College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China.
authors.forename: Mian
authors.initials: M
authors.lastname: Guo
authors.forename: Hang
authors.initials: H
authors.lastname: Dong
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.forename: Ben
authors.initials: B
authors.lastname: Cheng
authors.forename: Yun-qing
authors.initials: YQ
authors.lastname: Huang
authors.forename: Yu-qi
authors.initials: YQ
authors.lastname: Feng
authors.forename: Aiwen
authors.initials: A
authors.lastname: Lei
mesh_terms: D055162:Biocatalysis; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004852:Epoxy Compounds / Q000737:chemistry; D017613:Iodine Compounds / Q000737:chemistry*; D007462:Iodobenzenes / Q000737:chemistry*; D007700:Kinetics; D008345:Manganese / Q000737:chemistry*; D008665:Metalloporphyrins / Q000737:chemistry*; D009947:Organotin Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D013379:Substrate Specificity; D013997:Time Factors
chemical_list: D004852:Epoxy Compounds; D017613:Iodine Compounds; D007462:Iodobenzenes; D008665:Metalloporphyrins; D009947:Organotin Compounds; D010636:Phenols; D008345:Manganese; D003577:Cytochrome P-450 Enzyme System; C019584:2,4,6-tri-tert-butylphenol