title: The iron electron-nuclear double resonance (ENDOR) of 4-Fe clusters in iron-sulfur proteins from Chromatium and Clostridium pasteurianum.
abstract: Iron electron-nuclear double resonance (ENDOR) measurements were made of the 4-Fe clusters in oxidized Chromatium high-potential iron-sulfur protein, dithionite-reduced high-potential iron-sulfur protein in 80% dimethylsulphoxide, fully reduced Clostridium pasteurianum ferredoxin in aqueous solution and in 80% dimethylsulfoxide. The hyperfine couplings determined show that: i) the electron distribution in each case is nearly symmetric; ii) there are two types of iron in oxidized high potential iron-sulfur protein; iii) only one type of iron is observed in each fully reduced 4-Fe cluster; iv) the data also suggest a greater electron delocalization onto the ligands as compared to the 2-Fe ferredoxins.
mesh_terms: D001426:Bacterial Proteins; D001665:Binding Sites; D002844:Chromatium / Q000032:analysis*; D003013:Clostridium / Q000032:analysis*; D004578:Electron Spin Resonance Spectroscopy; D007501:Iron / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy; D008667:Metalloproteins; D010084:Oxidation-Reduction; D011485:Protein Binding; D011487:Protein Conformation; D013455:Sulfur / Q000032:analysis
chemical_list: D001426:Bacterial Proteins; D008667:Metalloproteins; D013455:Sulfur; D007501:Iron