PURIFICATION AND CHARACTERIZATION OF SILV ER-INDUCED METALLOTHIONEIN IN RAT-LIVER

The rat liver metallothionein was induced by subactaneous injections o f silver nitrate and was purified to homogeneity by using homogenizati on, ethanoI precipitation, Sephadex G-75 chromatography and chromatogr aphy on DEAE-52, Anion exchange chromatography yielded two isoforms of metallothionein, MT-I and MT-2, in which the molar ratios of Ag+, Zn2 + and Cu+ bound are 7, 2 and 2, respectively, It was also found that t he ratios were slightly affected by the dose of silver nitrate, which indicate that the two endogenous essential metals, Cu and Zn, accompan ying silver showed competition with the exogenous heavy metal ions, MT has different selectivities towards metals.