title: g-Strain, ENDOR, and structure of active centers of two-iron ferredoxins.
abstract: Collaborative chemical and spectroscopic work from several laboratories resulted in a qualitative structure for the active center in the two-iron ferredoxins, with each iron being in a distorted tetrahedron of sulfur atoms (two acid-labile sulfurs bridging the two iron atoms and the other two from cysteine sulfurs). Subsequent X-ray data from other laboratories confirmed this structure. Detailed EPR spectral syntheses showed that there is a distribution of structures in any given protein (even in a single crystal) resulting in a distribution of the principal values of the g tensor, which may be described by a statistical distribution of still another tensor whose principal axes are, in general, not coincident with the principal-axis frame of the g tensor.
authors: Department of Surgery, The University of Michigan Health System, Ann Arbor, MI 48109-0592, USA. wrdunham@umich.edu
authors: W Richard
authors: WR
authors: Dunham
authors: Richard H
authors: RH
authors: Sands
mesh_terms: D003461:Crystallography / Q000379:methods*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D005288:Ferredoxins / Q000737:chemistry* / Q000145:classification*; D007501:Iron / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D005288:Ferredoxins; D007501:Iron