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Published on: December 16, 2013
Formation and properties of a stable 'high-potential' copper-iron-sulphur cluster in a ferredoxin
J N Butt1, J Niles, F A Armstrong
1Department of Chemistry, University of California, Irvine 92717, USA.
Abstract:
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.
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