Iron-sulfur proteins of the green photosynthetic bacterium Chlorobium.
The iron-sulfur proteins of the green photosynthetic bacterium Chlorobium have been characterized by oxidation-reduction potentiometry in conjunction with low-temperature electron paramagnetic resonance spectroscopy. Chlorobium ferredoxin was the only iron-sulfur protein detected in the soluble fraction; no high-potential iron-sulfur protein was observed. In addition, high-potential iron-sulfur protein was not detected in the chromatophores. Four chromatophore-bound iron-sulfur proteins were detected. One is the "Rieske" type iron-sulfur protein with a g-value of 1.90 in the reduced state; the protein has a midpoint potential of + 160 mV (pH 7.0), and this potential is pH dependent. Three g=1.94 chromatophore-bound iron-sulfur proteins were observed, with midpoint potentials of -25, -175, and about -550 mV. A possible role for the latter iron-sulfur protein in the primary photochemical reaction in Chlorobium is considered.
D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000032:analysis; D008667:Metalloproteins / Q000032:analysis; D010084:Oxidation-Reduction; D011485:Protein Binding; D011487:Protein Conformation; D012244:Rhodospirillaceae / Q000032:analysis*; D013455:Sulfur / Q000032:analysis
D008667:Metalloproteins; D013455:Sulfur; D007501:Iron