Document Type
Article
Publication Date
3-15-2009
Publication Title
International Journal of Quantum Chemistry
Abstract
The oxidation of H-cluster in gas phase, and in aqueous enzyme phase, has been investigated by means of quantum mechanics (QM) and combined quantum mechanics–molecular mechanics (QM/MM). Several potential reaction pathways (in the above-mentioned chemical environments) have been studied, wherein only the aqueous enzyme phase has been found to lead to an inhibited hydroxylated cluster. Specifically, the inhibitory process occurs at the distal iron (Fed) of the catalytic H-cluster (which isalso the atom involved in H2 synthesis). The processes involved in the H-cluster oxidative pathways are O2 binding, e− transfer, protonation, and H2O removal. We found that oxygen binding is nonspontaneous in gas phase, and spontaneous for aqueous enzyme phase where both Fe atoms have oxidation state II; however, it is spontaneous for the partially oxidized and reduced clusters in both phases. Hence, in the protein environment the hydroxylated H-cluster is obtained by means of completely exergonic reaction pathway starting with proton transfer. A unifying endeavor has been carried out for the purpose of understanding the thermodynamic results vis-à-vis several other performed electronic structural methods, such as frontier molecular orbitals (FMO), natural bond orbital partial charges (NBO), and H-cluster geometrical analysis. An interesting result of the FMO examination (for gas phase) is that an e− is transferred to LUMOα rather than to SOMOβ, which is unexpected because SOMOβ usually resides in a lower energy rather than LUMOα for open-shell clusters.
Recommended Citation
Dogaru, Daniela; Motiu, Stefan; and Gogonea, Valentin, "Inactivation of [Fe-Fe]-Hydrogenase by O2. Thermodynamics and Frontier Molecular Orbitals Analyses" (2009). Chemistry Faculty Publications. 316.
https://engagedscholarship.csuohio.edu/scichem_facpub/316
DOI
10.1002/qua.21875
Version
Postprint
Publisher's Statement
This is the accepted version of the following article: Dogaru, D.; Motiu, S.; Gogonea, V. Inactivation of [Fe-Fe]-hydrogenase by O2. Thermodynamics and frontier molecular orbitals analyses. International Journal of Quantum Chemistry 2009, 109, 876-889., which has been published in final form at: http://onlinelibrary.wiley.com/doi/10.1002/qua.21875/abstract
Volume
109
Issue
4
