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)=O moiety and a doublet ligand radical. We found that an excited doublet state of the cpd1 is composed of a singlet Fe(IV)=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.
Original language | English |
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Pages (from-to) | 631-650 |
Number of pages | 20 |
Journal | International Journal of Quantum Chemistry |
Volume | 108 |
Issue number | 4 |
DOIs | |
Publication status | Published - Mar 15 2008 |
Externally published | Yes |
Keywords
- Density-functional theory
- Electronic structures
- Natural orbital analysis
- P450
- Reaction mechanisms
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Physical and Theoretical Chemistry