Probing the structural effects on the intrinsic electronic and redox properties of [2Fe-2S]+ clusters,a broken-symmetry density functional theory study

摘要

In biological electron transport chains,[2Fe-2S] clusters have versatile electrochemical properties and serve as important electron carriers in a wide variety of biological processes.To understand structural effects on the variation in reduction potentials in [2Fe-2S] proteins,a series of [2Fe-2S] protein analogs with bidentate ligands(-SC2H4NH2)were recently produced by collision-induced dissociation of [Fe4S4(L)4]2-(L=SC2H4NH2).Combined with photo-electron spectroscopy findings,the reaction mechanisms of [Fe4S4(L)4]2- to [Fe2S2(L)2]- and the structural effects of ligands on the electronic and redox properties of the [2Fe-2S] clusters are investigated here using broken-symmetry density functional theory method.Our calculations suggest that [Fe2S2(eta2-L)(cis-L)]- and [Fe2S2(eta2-L)2]_ are the experimentally observed [2Fe-2S] products,which are generated via a fission process of [Fe4S4(L)4]2- followed by rearrangement of ligands of [Fe2S2(L)2]-.Moreover,structural variation of the ferrous center may dramatically affect the oxidation energy of the [2Fe-2S] clusters.