Influence of {text{NH - }}{{text{S}}^gamma } bonding interactions on the structure and dynamics of metallothioneins

Mammalian metallothioneins ( textM₇^textIIMTs {text{M}}_7^{text{IIMTs}} ) show a clustered arrangement of the metal ions and a nonregular protein structure. The solution structures of Cd₃-thiolate cluster containing β-domain of mouse β-MT-1 and rat β-MT-2 show high structural similarities, but widely differing structure dynamics. Molecular dynamics simulations revealed a substantially increased number of textNH - textS^g {text{NH - }}{{text{S}}^gamma } hydrogen bonds in β-MT-2, features likely responsible for the increased stability of the Cd₃-thiolate cluster and the enfolding protein domain. Alterations in the textNH - textS^g {text{NH - }}{{text{S}}^gamma } hydrogen-bonding network may provide a rationale for the differences in dynamic properties encountered in the β-domains of MT-1, -2, and -3 isoforms, believed to be essential for their different biological function.