title: The high potential iron-sulfur cluster of aconitase is a binuclear iron-sulfur cluster.
abstract: It has been reported (Ruzicka, F.J., and Beinert, H. (1978) J. Biol. Chem. 253, 2514-2517) that aconitase in the oxidized state, as isolated, shows an electron paramagnetic resonance signal centered at g = 2.01, typical of high potential iron-sulfur proteins. Since the magnetic state corresponding to this signal has thus far only been found in tetranuclear iron-sulfur clusters in model compounds and proteins, it could be expected that aconitase also contains a [4Fe-4S] cluster. We show here that core extrusion, in the presence of hexamethylphosphoramide and o-xylyl-alpha,alpha'-dithiol and subsequent ligand exchange with p-trifluoromethylbenzenethiol yield absorption spectra typical of binuclear iron-sulfur clusters. According to the absorbance measured, the concentration of the extruded [2Fe-2S] cluster quantitatively accounts for the iron-sulfur content of the preparations examined. Preliminary studies of the 19F nuclear magnetic resonance spectrum obtained on extrusion with p-trifluoromethylbenzenethiol confirm the presence of a binuclear cluster in aconitase.
mesh_terms: D000154:Aconitate Hydratase; D000818:Animals; D002417:Cattle; D007501:Iron / Q000032:analysis; D007506:Iron-Sulfur Proteins; D009682:Magnetic Resonance Spectroscopy; D008667:Metalloproteins; D008970:Molecular Weight; D009206:Myocardium / Q000201:enzymology; D010084:Oxidation-Reduction; D011485:Protein Binding; D011487:Protein Conformation; D013053:Spectrophotometry; D013455:Sulfur / Q000032:analysis
chemical_list: D007506:Iron-Sulfur Proteins; D008667:Metalloproteins; D013455:Sulfur; D007501:Iron; D000154:Aconitate Hydratase