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- Title
Theory of chemical bonds in metalloenzymes. VII. Hybrid-density functional theory studies on the electronic structures of P450.
- Authors
Shoji, Mitsuo; Isobe, Hiroshi; Saito, Toru; Yabushita, Hirotaka; Koizumi, Kenichi; Kitagawa, Yasutaka; Yamanaka, Shusuke; Kawakami, Takashi; Okumura, Mitsutaka; Hagiwara, Masayuki; Yamaguchi, Kizashi
- Abstract
A first principle investigation has been carried out for intermediate states of the catalytic cycle of a cytochrome P450. To elucidate the whole catalytic cycle of P450, the electronic and geometrical structures are investigated not only at each ground state but also at low-lying energy levels. Using the natural orbital analysis, the nature of chemical bonds and magnetic interactions are investigated. The ground state of the Compound 1 (cpd1) is calculated to be a doublet state, which is generated by the antiferromagnetic coupling between a triplet Fe(IV)&dbond;O moiety and a doublet ligand radical. We found that an excited doublet state of the cpd1 is composed of a singlet Fe(IV)&dbond;O and a doublet ligand radical. This excited state lies 20.8 kcal mol-1 above the ground spin state, which is a non-negligible energy level as compared with the activation energy barrier of ΔE# = 26.6 kcal mol-1. The reaction path of the ground state of cpd1 is investigated on the basis of the model reaction: 3O(3p) + CH4. The computational results suggest that the reactions of P450 at the ground and excited states proceed through abstraction (3O-model) and insertion (1O-model) mechanisms, respectively. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
- Subjects
METALLOENZYMES; ELECTRONIC structure; ENERGY levels (Quantum mechanics); QUANTUM theory; PHYSICAL &; theoretical chemistry; QUANTUM chemistry
- Publication
International Journal of Quantum Chemistry, 2008, Vol 108, Issue 4, p631
- ISSN
0020-7608
- Publication type
Article
- DOI
10.1002/qua.21547