| Type of Document |
Master's Thesis |
| Author |
Cotton, Marcia S.
|
| Author's Email Address |
mcotto3@lsu.edu |
| URN |
etd-11162006-104012 |
| Title |
MCD and Magnetization Studies of NifB/NifZ Minus Molybdenum Iron Protein from Azotobacter vinelandii |
| Degree |
Master of Science (M.S.) |
| Department |
Chemistry |
| Advisory Committee |
| Advisor Name |
Title |
| Brian J. Hales |
Committee Chair |
| Andrew W. Maverick |
Committee Member |
| George Stanley |
Committee Member |
|
| Keywords |
- vt mcd
- magnetization
- nifbnifz minus
- mofe protein
|
| Date of Defense |
2006-11-10 |
| Availability |
unrestricted |
Abstract
This study reports a characterization of the iron-sulfur clusters of the MoFe protein expressed by the nifBnifZ deletion strain of A. vinelandii. VT-MCD spectroscopic and magnetization analysis of as-isolated ΔnifBΔnifZ MoFe protein were undertaken. VT-MCD spectra of as-isolated ΔnifBΔnifZ MoFe protein contains bands remarkably similar to those seen in as-isolated ΔnifH MoFe protein, assigned to arise from an [4Fe-4S]+ cluster. The low-temperature magnetization curve of as-isolated ΔnifBΔnifZ MoFe protein reveals the MCD spectra bands stem from an S = ½ spin system with diamagnetic contributions of some other species. As-isolated ΔnifBΔnifZ MoFe protein is compared with as-isolated ΔnifH MoFe protein, which contains a P-cluster precursor, and the as-isolated ΔnifB MoFe protein, which contains a fully assembled P-cluster ([8Fe-7S)]. Using nonlinear regression, the experimental magnetization curve of as-isolated ΔnifBΔnifZ MoFe protein is compared and factored to contributions from as-isolated ΔnifH MoFe protein and as-isolated ΔnifB MoFe protein. The simulation suggests a 1:1 ratio of ΔnifH MoFe protein to ΔnifB MoFe protein. These results suggests the as-isolated ΔnifBΔnifZ MoFe protein has an αβ subunit pair that contains a P-cluster and the other αβ subunit pair contains a latent (defined as immature, or potential) P-cluster (two [4Fe-4S] or P-cluster precursor).
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Cotton_thesis.pdf |
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