title: Manganese substituted Compound I of cytochrome P450 biomimetics: a comparative reactivity study of Mn(V)-oxo versus Mn(IV)-oxo species.
abstract: Manganese-oxo porphyrins have been well studied as biomimetic models of cytochromes P450 and are known to be able to catalyze substrate hydroxylation reactions. Recent experimental studies [J.Y. Lee, Y.-M. Lee, H. Kotani, W. Nam, S. Fukuzumi, Chem. Commun. (2009) 704] showed that Mn(V)-oxo porphyrins react rapidly with 10-methyl-9,10-dihydroacridine (AcrH(2)) via a proton-coupled-electron-transfer followed by an electron transfer. In this work, we present a computational study on the reactivity patterns of Mn(V)-oxo and Mn(IV)-oxo with respect to AcrH(2). This study shows that although both oxidants are capable of hydroxylating AcrH(2), the Mn(V)-oxo species is the more active oxidant. We have generalized these observations with thermodynamic cycles that explain the reaction mechanisms and electron transfer processes. For the Mn(V)-oxo mechanism the reactions proceed with a fast spin state crossing from the ground state singlet to the triplet spin state prior to a hydrogen atom transfer followed by another electron transfer. The present results are fully consistent with previous studies on iron-oxo porphyrins and manganese-oxo porphyrins and shows that the interplay of low lying singlet and triplet spin state surfaces influences the reaction mechanisms and kinetics.
authors.affiliation: The Manchester Interdisciplinary Biocenter, School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, UK.
authors.forename: Reza
authors.initials: R
authors.lastname: Latifi
authors.forename: Laleh
authors.initials: L
authors.lastname: Tahsini
authors.forename: Baharan
authors.initials: B
authors.lastname: Karamzadeh
authors.forename: Nasser
authors.initials: N
authors.lastname: Safari
authors.forename: Wonwoo
authors.initials: W
authors.lastname: Nam
authors.forename: Sam P
authors.initials: SP
authors.lastname: de Visser
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry*; D006801:Humans; D006900:Hydroxylation; D008345:Manganese / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011166:Porphyrins / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D011166:Porphyrins; D008345:Manganese; D003577:Cytochrome P-450 Enzyme System