Interconversion between [2Fe–2S] and [4Fe–4S] cluster glutathione complexes

Abstract

We present here how different iron-sulfide-glutathione ratios, applied in <i>in vitro</i> conditions comparable to those present in the mitochondrial matrix, affect the speciation of iron-sulfur cluster glutathione complexes. An excess of sulfide with respect to iron ions promotes the formation of a tetranuclear [Fe^II₂Fe^III₂S₄(GS)₄]^2- complex, while an excess of iron ions favors the formation of a dinuclear [Fe^IIFe^IIIS₂(GS)₄]^3- complex. These two complexes establish an interconversion equilibrium. The latter might play a role in the composition of the mitochondrial labile iron pool potentially contributing to the regulation of cellular iron homeostasis.