title: Refinement of the 7 Fe ferredoxin from Azotobacter vinelandii at 1.9 A resolution.
abstract: The recently redetermined structure of the 7 Fe ferredoxin from Azotobacter vinelandii has been refined against a new 1.9 A data set. The crystallographic R-factor is 0.215 for all 9586 observed reflections 8.0 to 1.9 A. The model contains 106 amino acid residues, two Fe-S clusters and 21 water molecules. The root-mean-square deviations from ideality of bonds and angles are 0.014 A and 3.3 degrees, respectively. The refinement confirms the presence of two free cysteines: the thiol of C11 is in association with the side-chain of K100; the thiol of C24 is 3.35 A from inorganic sulfur of the [4 Fe-4 S] cluster. The refinement confirms a [3 Fe-4 S] model for the 3 Fe cluster. The two Fe-S clusters have similar bond distances and angles. The structure of the protein for residues 1 to 57 superposes within 0.85 A on residues 1 to 53 of the 8 Fe ferredoxin structure for main-chain N, CA and C atoms, if residues 9, 10, 29 and 30 of 7 Fe ferredoxin are omitted. These residues are part of two loops in contact with residues of the extended C-terminal chain of 7 Fe ferredoxin.
authors.affiliation: Research Institute of Scripps Clinic, La Jolla, CA 92037.
authors.forename: C D
authors.initials: CD
authors.lastname: Stout
mesh_terms: D000596:Amino Acids; D001395:Azotobacter; D001426:Bacterial Proteins; D005288:Ferredoxins; D006860:Hydrogen Bonding; D008958:Models, Molecular; D011487:Protein Conformation; D014961:X-Ray Diffraction
chemical_list: C058978:7 Fe ferredoxin; D000596:Amino Acids; D001426:Bacterial Proteins; D005288:Ferredoxins