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 (AcrH2) 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 AcrH2. This study shows that although both oxidants are capable of hydroxylating AcrH2, the MnV-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 MnV-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.
Original language | English |
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Pages (from-to) | 4-13 |
Number of pages | 10 |
Journal | Archives of Biochemistry and Biophysics |
Volume | 507 |
Issue number | 1 |
DOIs | |
State | Published - 1 Mar 2011 |
Keywords
- Biomimetic
- Hydride transfer
- Hydroxylation
- Iron-oxo
- Manganese-oxo
- Porphyrin