scholarly journals The Electronic Structure of FeV-cofactor in Vanadium-Dependent Nitrogenase

2021 ◽  
Author(s):  
Zhi-yong Yang ◽  
Emilio Jimenez-Vicente ◽  
Hayden Kallas ◽  
Dmitriy A Lukoyanov ◽  
Hao Yang ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Active Site ◽  
Resting State ◽  
Metal Cofactor ◽  
Open Question

The electronic structure of the active-site metal cofactor (FeV-cofactor) of resting-state V-dependent nitrogenase has been an open question, with earlier studies indicating that it exhibits a broad S = 3/2...

scholarly journals In situ characterization of cofacial Co(IV) centers in Co4O4 cubane: Modeling the high-valent active site in oxygen-evolving catalysts

2017 ◽  
Vol 114 (15) ◽  
pp. 3855-3860 ◽  
Author(s):  
Casey N. Brodsky ◽  
Ryan G. Hadt ◽  
Dugan Hayes ◽  
Benjamin J. Reinhart ◽  
Nancy Li ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Active Site ◽  
Resting State ◽  
Structural Model ◽  
Reorganization Energy ◽  
Electrochemical Kinetics ◽  
Absorption Data ◽  
High Valent ◽  
Oxygen Evolving

The Co4O4 cubane is a representative structural model of oxidic cobalt oxygen-evolving catalysts (Co-OECs). The Co-OECs are active when residing at two oxidation levels above an all-Co(III) resting state. This doubly oxidized Co(IV)2 state may be captured in a Co(III)2(IV)2 cubane. We demonstrate that the Co(III)2(IV)2 cubane may be electrochemically generated and the electronic properties of this unique high-valent state may be probed by in situ spectroscopy. Intervalence charge-transfer (IVCT) bands in the near-IR are observed for the Co(III)2(IV)2 cubane, and spectroscopic analysis together with electrochemical kinetics measurements reveal a larger reorganization energy and a smaller electron transfer rate constant for the doubly versus singly oxidized cubane. Spectroelectrochemical X-ray absorption data further reveal systematic spectral changes with successive oxidations from the cubane resting state. Electronic structure calculations correlated to experimental data suggest that this state is best represented as a localized, antiferromagnetically coupled Co(IV)2 dimer. The exchange coupling in the cofacial Co(IV)2 site allows for parallels to be drawn between the electronic structure of the Co4O4 cubane model system and the high-valent active site of the Co-OEC, with specific emphasis on the manifestation of a doubly oxidized Co(IV)2 center on O–O bond formation.

Spectroscopic studies on plastocyanin single crystals: a detailed electronic structure determination of the blue copper active site

1981 ◽  
Vol 103 (15) ◽  
pp. 4382-4388 ◽  
Author(s):  
K. W. Penfield ◽  
R. R. Gay ◽  
R. S. Himmelwright ◽  
N. C. Eickman ◽  
V. A. Norris ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Single Crystals ◽  
Structure Determination ◽  
Active Site ◽  
Spectroscopic Studies ◽  
Blue Copper

scholarly journals Calculation of Higher Protonation States and of a New Resting State for Vanadium Chloroperoxidase Using QM/MM, with an Atom-in-Molecules Analysis

2020 ◽  
Author(s):  
Gregory Anderson ◽  
Raghu Nath Behera ◽  
Ravi V. Gomatam
Keyword(s):  
Hydrogen Bonding ◽  
Electronic Structure ◽  
Resting State ◽  
Natural Bond Orbital ◽  
Atoms In Molecules ◽  
Aim Analysis ◽  
Neutral Ph

<p></p><p><b>ABSTRACT</b>. <a></a><a></a><a>Earlier QM/MM studies of the resting state of vanadium chloroperoxidase (VCPO) focused on the diprotonated states of the vanadate cofactor. Herein, we report a new extensive QM/MM study that includes the tri- and quadprotonated states of VCPO at neutral pH. We identify certain di- and triprotonated states as being candidates for the resting state based on a comparison of relative energies. The quadprotonated states as well as some of the triprotonated states are ruled out as the resting state. An Atoms-in-Molecules (AIM) analysis of the complex hydrogen bonding around the vanadate cofactor helps to explain the relative energies of the protonation states considered herein, and it also indicates new hydrogen bonding which has not been recognized previously. A Natural Bond Orbital (NBO) study is presented to give a better understanding of the electronic structure of the vanadate co-factor.</a></p><br><p></p>

Sign in / Sign up

Export Citation Format

Share Document