Metallothionein Zn2+- and Cu2+-clusters from first-principles calculations†
Abstract
Detailed electronic structures of Zn(II) and Cu(II) clusters from metallothioneins (MT) have been obtained using density functional theory (DFT), in order to investigate how oxidative stress-caused Cu(II) intermediates affect Zn-binding to MT and cooperatively lead to Cu(I)MT. The inferred accuracy is ∼0.02–0.03 Å for metal–thiolate bond lengths for the models that are the most realistic MT models so far studied by DFT. We find terminal Zn–S and Cu–S bond lengths of 2.35–2.38 Å and 2.30–2.34 Å, whereas bridging M–S bonds are 0.05–0.11 Å longer. This electronic effect is also reflected in changes in electron density on bridging sulfurs. Various imposed backbone constraints quantify the sensitivity of cluster electronic structure towards