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Fundamental differences of substrate hydroxylation by high-valent Lron(IV)-Oxo models of cytochrome P450

Title
Fundamental differences of substrate hydroxylation by high-valent Lron(IV)-Oxo models of cytochrome P450
Authors
Tahsini L.Bagherzadeh M.Nam W.De Visser S.P.
Ewha Authors
남원우
SCOPUS Author ID
남원우scopus
Issue Date
2009
Journal Title
Inorganic Chemistry
ISSN
0020-1669JCR Link
Citation
vol. 48, no. 14, pp. 6661 - 6669
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
An Iron(lV)-oxo heme(+·) complex (Compound I, Cpd I) is the proposed active species of heme enzymes such as the cytochromes P450 and Is elusive; therefore, biomimetic studies on active site mimics give valuable Insight Into the fundamental properties of heme active species. In this work we present density functional theory (DFT) calculations on substrate hydroxylatlon by a Compound I mimic [FeIV=O(Por+̇)Cl] and its one-electron reduced form [FeIV=O(Por)Cl]-. Thus, recent experimental studies showed that [FeIV =O(Por)Cl]- is able to react with substrates via hydride transfer reactions [Jeong, Y. J.; Kang, Y.; Han, A.-R.; Lee, Y.-M.; Kotani, H.; Fukuzumi, S.; Nam, W. Angew. Chem., Int. Ed. 2008, 47, 7321 -7324]. By contrast, theoretical studies on camphor hydroxylation by these two oxidants concluded that the one-electron reduced form of Compound I is a sluggish oxidant of hydroxylation reactions [Altun, A.; Shalk, S.; Thiel, W. J. Am. Chem. Soc. 2007,129, 8978-8987]. To resolve the question why the one-electron reduced Compound I is an oxidant in one case and a sluggish oxidant in other cases, we have performed a DFT study on 10methyl-9,10-dihydro acridine (AcrH2) hydroxylation by [FeIV=O(Por+̇)Cl] and [FeIV=O(Por)Cl]-. The calculations presented in this work show that both [FeIV=O(Por)Cl]- and [Fe IV=O(Por)CI]- are plausible oxidants, but Fe IV=0(Por+̇)CI] reacts via much lower reaction barriers. Moreover, [FeIV=O(Por+̇)CI] reacts via hydride transfer, while [Fe IV=O(Por)CI]- by hydrogen abstraction. The differences between hydride and hydrogen atom transfer reactions have been rationalized with thermodynamic cycles and shown to be the result of differences in electron abstraction abilities of the two oxidants.Thus, the calculations predict that [FeIV=O(Por)Cl]- is only able to hydroxylate weak C-H bonds, whereas [FeIV=O(Por+̇)Cl] Is more versatile. © 2009 American Chemical Society.
DOI
10.1021/ic900593c
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자연과학대학 > 화학·나노과학전공 > Journal papers
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