Formation and properties of a stable 'high-potential' copper-iron-sulphur cluster in a ferredoxin.
A ferredoxin isolated from Desulfovibrio africanus contains a [3Fe-4S] cluster that reversibly binds a copper atom, yielding a stable product with a greatly increased reduction potential. The reaction is readily detected in protein molecules adsorbed as a film on an electrode surface. Electron paramagnetic resonance (EPR) and magnetic circular dichroism (MCD) spectra of oxidized and reduced bulk solution products support their assignment as [Cu3Fe-4S]2+ (S = 1/2) and [Cu3Fe-4S]1+ (S = 2) respectively, with copper bound formally as Cu(I). Cyanide causes selective loss of copper and regeneration of the [3Fe-4S] reactant. The results demonstrate the chemical feasibility of CuFeS clusters and suggest that they could exist naturally in biological systems.
Butt
J N
JN
Department of Chemistry, University of California, Irvine 92717, USA.
Niles
J
J
Armstrong
F A
FA
Breton
J
J
Thomson
A J
AJ
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D002942:Circular Dichroism; D003300:Copper / Q000737:chemistry*; D003901:Desulfovibrio / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005288:Ferredoxins / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D011487:Protein Conformation; D013455:Sulfur / Q000737:chemistry*
D001426:Bacterial Proteins; D005288:Ferredoxins; D013455:Sulfur; D003300:Copper; D007501:Iron