Investigating the influence of histidine residues on the metal ion binding ability of the wheat metallothionein γ-Ec-1 domain

The γ-domain of the wheat Ec-1 metallothionein contains a M(II)2Cys6 cluster. Mutation of one of the Cys residues to His increases the metal ion selectivity of the binding sites resulting in a mixed ZnCd cluster with Zn(II) nearly exclusively coordinated to the Cys3His site in accordance with the HSAB principle.87