PMID- 20160838
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20240312
IS  - 0020-7608 (Print)
IS  - 1097-461X (Electronic)
IS  - 0020-7608 (Linking)
VI  - 109
IP  - 4
DP  - 2009 Mar 15
TI  - Inactivation of [Fe-Fe]-Hydrogenase by O(2). Thermodynamics and Frontier 
      Molecular Orbitals Analyses.
PG  - 876-889
AB  - 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 (Fe(d)) of the 
      catalytic H-cluster (which is also the atom involved in H(2) synthesis). The 
      processes involved in the H-cluster oxidative pathways are O(2) binding, e(-) 
      transfer, protonation, and H(2)O removal.We found that oxygen binding is 
      non-spontaneous 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-a-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 LUMO(alpha) rather than to SOMO(beta), 
      which is unexpected because SOMO(beta) usually resides in a lower energy rather 
      than LUMO(alpha) for open-shell clusters.
FAU - Dogaru, Daniela
AU  - Dogaru D
AD  - Department of Chemistry, Cleveland State University, 2121 Euclid Avenue, 
      Cleveland, Ohio 44115.
FAU - Motiu, Stefan
AU  - Motiu S
FAU - Gogonea, Valentin
AU  - Gogonea V
LA  - eng
GR  - R15 GM070469/GM/NIGMS NIH HHS/United States
GR  - R15 GM070469-01/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PL  - United States
TA  - Int J Quantum Chem
JT  - International journal of quantum chemistry
JID - 9892351
PMC - PMC2613324
MID - NIHMS66629
EDAT- 2010/02/18 06:00
MHDA- 2010/02/18 06:01
PMCR- 2010/03/15
CRDT- 2010/02/18 06:00
PHST- 2010/02/18 06:00 [entrez]
PHST- 2010/02/18 06:00 [pubmed]
PHST- 2010/02/18 06:01 [medline]
PHST- 2010/03/15 00:00 [pmc-release]
AID - 10.1002/qua.21875 [doi]
PST - ppublish
SO  - Int J Quantum Chem. 2009 Mar 15;109(4):876-889. doi: 10.1002/qua.21875.