This project involves the use of novel techniques in quantum chemistry to study electronic structure problems at the active sites of iron-sulfur proteins, and of related mixed-metal clusters containing Mo, V, Co or Zn, in addition to iron. The principal goal is to understand the nature of spin-coupling in these systems, and to explore how these couplings influence their oxidation-reduction and catalytic properties. This will be accomplished through systematic variation of geometries in calculations on Heisenberg coupling constants, Mossbauer and electron spin resonance parameters (including g and hyperfine tensors) and electric fields and charge densities. All of the calculations will use the X alpha or local spin density effective potentials. Systems to be studied include: (a) three-iron clusters in both linear and pseudo-cubane geometries that are characteristic of active sites in several ferredoxins and in aconitase; (b) four-iron clusters that can exist in multiple oxidation states, with special attention paid to geometries that might allow intermediate or high-spin ground states; (c) models for four-iron clusters linked to a siroheme (as a model for sulfite reductase) or to citrate (as a model for an intermediate step in aconitase); (d) mixed metal clusters with XFe3 stoichiometries (X=Mo, V, Co, Zn), which are implicated in nitrogenase activity or which form useful test systems for our understanding of the active sites of iron-sulfur proteins in general.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM039914-03
Application #
3297189
Study Section
Metallobiochemistry Study Section (BMT)
Project Start
1988-04-01
Project End
1991-03-31
Budget Start
1990-04-01
Budget End
1991-03-31
Support Year
3
Fiscal Year
1990
Total Cost
Indirect Cost
Name
Scripps Research Institute
Department
Type
DUNS #
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Janowski, Pawel A; Liu, Chunmei; Deckman, Jason et al. (2016) Molecular dynamics simulation of triclinic lysozyme in a crystal lattice. Protein Sci 25:87-102
Mitra, Devrani; George, Simon J; Guo, Yisong et al. (2013) Characterization of [4Fe-4S] cluster vibrations and structure in nitrogenase Fe protein at three oxidation levels via combined NRVS, EXAFS, and DFT analyses. J Am Chem Soc 135:2530-43
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Mitra, Devrani; Pelmenschikov, Vladimir; Guo, Yisong et al. (2011) Dynamics of the [4Fe-4S] cluster in Pyrococcus furiosus D14C ferredoxin via nuclear resonance vibrational and resonance Raman spectroscopies, force field simulations, and density functional theory calculations. Biochemistry 50:5220-35
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Hopmann, Kathrin H; Noodleman, Louis; Ghosh, Abhik (2010) Spin coupling in Roussin's red and black salts. Chemistry 16:10397-408
Hopmann, Kathrin H; Ghosh, Abhik; Noodleman, Louis (2009) Density functional theory calculations on Mössbauer parameters of nonheme iron nitrosyls. Inorg Chem 48:9155-65
Guo, Yisong; Wang, Hongxin; Xiao, Yuming et al. (2008) Characterization of the Fe site in iron-sulfur cluster-free hydrogenase (Hmd) and of a model compound via nuclear resonance vibrational spectroscopy (NRVS). Inorg Chem 47:3969-77

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