Combining chemical labeling, bottom-Up and top-down ion-mobility mass spectrometry to identify metal-binding sites of partially metalated metallothionein

Shu Hua Chen, William K. Russell, David H. Russell

Research output: Contribution to journalArticle

26 Scopus citations


Metalation and demetalation of human metallothionein-2A (MT) with Cd 2+ is investigated by using chemical labeling and "bottom-up" and "top-down" proteomics approaches. Both metalation and demetalation of MT-2A by Cd2+ are shown to be domain specific and occur as two distinct processes. Metalation involves sequential addition of Cd2+ to the α-domain resulting in formation of an intermediate, Cd4MT. Chemical labeling with N-ethylmaleimide (NEM) and tandem mass spectrometry experiments clearly show that the four metal ions are located in the α-domain. In the presence of excess Cd2+, the Cd4MT intermediate reacts to add Cd2+ to the β-domain to yield the fully metalated Cd7MT. Demetalation occurs in the reverse order, i.e., Cd2+ is removed (by EDTA) first from the β-domain followed by Cd2+ removal from the α-domain. Metalation of human MT-2A is shown to be metal ion specific by comparing relative metal ion binding constants for Cd2+ and Zn2+.

Original languageEnglish (US)
Pages (from-to)3229-3237
Number of pages9
JournalAnalytical Chemistry
Issue number6
StatePublished - Mar 19 2013
Externally publishedYes


ASJC Scopus subject areas

  • Analytical Chemistry

Cite this