Table of Contents
Metal-Based Drugs
Volume 6, Issue 4-5, Pages 277-290
http://dx.doi.org/10.1155/MBD.1999.277

Spectroscopic Studies of Copper and Silver Binding to Metallothioneins

Department of Chemistry, The University of Westem Ontario, ON, London N6A 5B7, Canada

Copyright © 1999 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Mammalian metallothionein is remarkable in its metal binding properties: well-characterized species exist for metal to sulfur ratios of M7S20, M12S20, and M18S20, where M = Cd(ll), Zn(ll), Hg(ll), Ag(I), Au(I), and Cu(I). Circular dichroism and luminescence spectra provide rich details of a complicated metal binding chemistry when metals are added directly to the metal free- or zinc-containing protein. CD spectral data unambiguously identify key metal to protein stoichiometric ratios that result in well-defined structures. Emission spectra in the 450-750 nm region have been reported for metallothioneins containing Ag(I), Au(I), and Cu(I). The luminescence of Cu-MT can also be detected directly from mammalian and yeast cells. Qualitative and quantitative interpretations show that the final structure adopted by Ag-MT is not the same as that formed by Cu(I) ions in Cu-MT. XAFS structural data are reported for a number of metallothioneins, including Ag12-MT and Ag17-MT. Electrospray ionization mass spectrometry provides details on the species formed when Ag(I) binds to metallothionein. Mass spectral data are reported for metal-free MT 2A and Agn-MT (n = 14-18).