Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Chemical and spectroscopic study of ferredoxin l from Azotobacter vinellandii

Thesis/Dissertation ·
OSTI ID:5349389
Ferredoxin l of Azotobacter vinelandii is an iron sulfur protein containing one (4Fe-S) cluster and one (3Fe-3S) cluster. The structure and geometry of the 3Fe cluster is under dispute. The X-ray crystal structure of the protein describes the 3Fe cluster as a planar (3Fe-3S) cluster in which one of the iron atoms is ligated to a solvent accessible oxoligand, presumably from water or hydroxide. Efforts to displace the oxoligand were unsuccessful even when the protein was demonstrably denatured in 80% (V/V) dimethyl sulfoxide. In addition, comparison of the electron spin echo envelopes for H/sub 2/O and D/sub 2/O-equilibrated samples of ferredoxin l showed only a slight deuterium modulation, far less than would be expected were water to be bound as an iron ligand. Studies were also conducted in an effort to characterize the hyperfine-shifted resonances in the proton magnetic resonance spectrum of ferredoxin l. A. vinelandii was grown on synthetic media that contained isotopically labelled cystine as the only sulfur source. In independent experiments ferredoxin l was isolated from organism that was shown on such medium that contained alpha-/sup 2/H-dl-cystine, beta=/sup 2/H-dl-cystine, or betal-/sup 13/C-dl-cystine. However, ferredoxins isolated from these media were devoid of the corresponding isotopic labels. Thus, the experiments designed to characterize the hyperfine-shifted resonances of ferredoxin l were unsuccessful.
Research Organization:
City Univ. of New York, NY (USA)
OSTI ID:
5349389
Country of Publication:
United States
Language:
English