Ferrocene-substituted dithio-o-carborane isomers: influence on the native conformation of myoglobin protein.

Biointeractions between two organometallic compounds, a pair of ferrocene-substituted dithio-o-carborane isomers (C(14)H(20)B(10)FeS(2); denoted as FcSB1 and FcSB2), and myoglobin (Mb) have been investigated by means of electrochemistry, fluorescence, circular dichroism, and UV/Vis absorption spectroscopy. Our observations demonstrate that FcSB1 and FcSB2 could coordinate to the axial position trans to the histidine imidazole that induces the change of the heme iron from the high spin state to the low spin state and the changes of the conformation of the aromatic fluorophores of the selected heme protein. Such influences attribute to the structural features of FcSB1 and FcSB2 containing sulfur donor atoms and hydrophobic ferrocenyl and carboranyl units that leads to specific binding modalities with Mb. This study provides an insight into the understanding of relevant biointeractions between the new type of ferrocene-carborane conjugates and hemoproteins, and might shed light on the promising bioapplications of these multifunctional organometallic complexes.