Evidence for zinc ion sharing in metallothionein dimers provided by collision-induced dissociation

TL;DR

This study uses collision-induced dissociation to investigate zinc ion sharing in metallothionein dimers, revealing that native dimers share zinc ions while denatured ones do not, highlighting mass spectrometry's potential in zinc biochemistry.

Contribution

It demonstrates that collision-induced dissociation can distinguish zinc sharing in metallothionein dimers, providing new insights into zinc coordination in these proteins.

Findings

Native dimers share zinc ions

Denatured dimers do not share zinc ions

Mass spectrometry reveals zinc ion sharing in metallothionein

Abstract

Nanospray and collisionally-induced dissociation are used to evaluate the presence and absence of interstrand co-chelation of zinc ions in dimers of metallothionein. As was reported in a previous publication from this laboratory, co-chelation stabilizes the dimer to collisional activation, and facilitates asymmetrical zinc ion transfers during fragmentation. In the case of metallothionein, dimers of the holoprotein are found to share zinc ions, while dimers of metallothionein, in which one domain has been denatured, do not. Zinc ions are silent to most physicochemical probes, e.g., NMR and Mossbauer spectroscopies, and the capability of mass spectrometry to provide information on zinc complexes has widespread potential application in biochemistry.