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75672 
Journal Article 
Metallothionein: A cadmium- and zinc-containing protein from equine renal cortex 
Kägi, JHR; Vallee, BL 
1960 
Yes 
Journal of Biological Chemistry
ISSN: 0021-9258
EISSN: 1083-351X 
235 
12 
3460-3465 
English 
13750713 
BCI:BCI19613600023177 
Metallothionein, a protein of small molecular weight, isolated from equine renal cortex contains 2.9% of cadmium, 0.6% of zinc, and 4% of sulfur. The protein, homogeneous on ultracentrifugation, but containing minor impurities on electrophoresis, does not absorb radiation at and near 280 m'mu', corresponding to a very low content of aromatic amino acids. A large number of cysteine residues account for the high sulfur content. The stoichiometry between titratable --SH groups and metal atoms, the displacement of the metals by --SH specific agents, and the selective removal of zinc and cadmium by hydrogen ions, all suggest isomorphous binding of the two metals to the protein through mercaptide linkages. Although the biological function of metallothionein is not known thus far, the specific association of cadmium with this macromolecule suggests a biological role of this cadmium-containing protein.