dc.contributor |
Háskóli Íslands |
dc.contributor |
University of Iceland |
dc.contributor.author |
Benediktsson, Bardi |
dc.contributor.author |
Bjornsson, Ragnar |
dc.date.accessioned |
2020-11-24T12:37:16Z |
dc.date.available |
2020-11-24T12:37:16Z |
dc.date.issued |
2020-08-05 |
dc.identifier.citation |
Benediktsson, B. and R. Bjornsson (2020). "Quantum Mechanics/Molecular Mechanics Study of Resting-State Vanadium Nitrogenase: Molecular and Electronic Structure of the Iron–Vanadium Cofactor." Inorganic Chemistry 59(16): 11514-11527. |
dc.identifier.issn |
0020-1669 |
dc.identifier.issn |
1520-510X (eISSN) |
dc.identifier.uri |
https://hdl.handle.net/20.500.11815/2235 |
dc.description |
Publisher's version (útgefin grein) |
dc.description.abstract |
The nitrogenase enzymes are responsible for all biological nitrogen reduction. How this is accomplished at the atomic level, however, has still not been established. The molybdenum-dependent nitrogenase has been extensively studied and is the most active catalyst for dinitrogen reduction of the nitrogenase enzymes. The vanadium-dependent form, on the other hand, displays different reactivity, being capable of CO and CO2 reduction to hydrocarbons. Only recently did a crystal structure of the VFe protein of vanadium nitrogenase become available, paving the way for detailed theoretical studies of the iron-vanadium cofactor (FeVco) within the protein matrix. The crystal structure revealed a bridging 4-atom ligand between two Fe atoms, proposed to be either a CO32- or NO3- ligand. Using a quantum mechanics/molecular mechanics model of the VFe protein, starting from the 1.35 Å crystal structure, we have systematically explored multiple computational models for FeVco, considering either a CO32- or NO3- ligand, three different redox states, and multiple broken-symmetry states. We find that only a [VFe7S8C(CO3)]2- model for FeVco reproduces the crystal structure of FeVco well, as seen in a comparison of the Fe-Fe and V-Fe distances in the computed models. Furthermore, a broken-symmetry solution with Fe2, Fe3, and Fe5 spin-down (BS7-235) is energetically preferred. The electronic structure of the [VFe7S8C(CO3)]2- BS7-235 model is compared to our [MoFe7S9C]- BS7-235 model of FeMoco via localized orbital analysis and is discussed in terms of local oxidation states and different degrees of delocalization. As previously found from Fe X-ray absorption spectroscopy studies, the Fe part of FeVco is reduced compared to FeMoco, and the calculations reveal Fe5 as locally ferrous. This suggests resting-state FeVco to be analogous to an unprotonated E1 state of FeMoco. Furthermore, V-Fe interactions in FeVco are not as strong compared to Mo-Fe interactions in FeMoco. These clear differences in the electronic structures of otherwise similar cofactors suggest an explanation for distinct differences in reactivity. |
dc.description.sponsorship |
R.B. acknowledges support from the Icelandic Research Fund (Grants 141218051 and 162880051) and University of Iceland Research Fund. Open Access funding was provided by the Max Planck Society. |
dc.format.extent |
11514-11527 |
dc.language.iso |
en |
dc.publisher |
American Chemical Society (ACS) |
dc.relation.ispartofseries |
Inorganic Chemistry;59(16) |
dc.rights |
info:eu-repo/semantics/openAccess |
dc.subject |
FeMo cofactor |
dc.subject |
X-rays |
dc.subject |
Ligands |
dc.subject |
QM/MM |
dc.subject |
Crystal structure |
dc.subject |
Skammtafræði |
dc.title |
Quantum Mechanics/Molecular Mechanics Study of Resting-State Vanadium Nitrogenase: Molecular and Electronic Structure of the Iron–Vanadium Cofactor |
dc.type |
info:eu-repo/semantics/article |
dcterms.license |
This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. |
dc.description.version |
Peer Reviewed |
dc.identifier.journal |
Inorganic Chemistry |
dc.identifier.doi |
10.1021/acs.inorgchem.0c01320 |
dc.relation.url |
https://pubs.acs.org/doi/10.1021/acs.inorgchem.0c01320 |
dc.contributor.department |
Raunvísindastofnun (HÍ) |
dc.contributor.department |
Science Institute (UI) |
dc.contributor.school |
Verkfræði- og náttúruvísindasvið (HÍ) |
dc.contributor.school |
School of Engineering and Natural Sciences (UI) |