  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.
