ISOLATION AND CHARACTERIZATION OF A HEPATIC METALLOTHIONEIN FROM MICE

  • 1 January 1975
    • journal article
    • research article
    • Vol. 5  (6) , 396-403
Abstract
Mice were given cadmium chloride orally for 18 wk, after which they were given 2 s.c. injections of cadmium chloride. Cd- and Zn-containing proteins were obtained from livers by ultracentrifugation, Sephadex chromatography and isoelectric focusing. Metallothionein with a pI [isoelectric point] of 4.2 at 8.degree. C was separated from other proteins (possibly including other forms of metallothionein) by the isoelectric procedure. The metallothionein with pI = 4.2 had a high E250 [absorbance at 250 nm], reflecting abundant Cd-SH bonds, in accord with amino acid analysis, which gave a cysteine content of 34.6 residues % and showed an absence of aromatic amino acids. These results indicated a very high purity of the form of metallothionein isolated after isoelectric focusing.